android: 实时画面卡顿根因是软件画布（6.5→15.1fps），标注统一 + 7x7 细节增强

卡顿: 热像走 SurfaceView.lockCanvas 的软件画布, 每帧在 CPU 上做 320x240 ->
~810x1080 双线性放大 + 清整屏, 实测只有 6.5 帧/秒、单帧 134ms。dumpsys gfxinfo
看不到这条路径(只统计 Compose), 故给渲染线程加自测量日志才定位到。改用
lockHardwareCanvas(API29+, 旧系统回退) 后 15.1 帧/秒、单帧 6.4ms。
同时消除每帧垃圾: 复用翻转缓冲/标记列表, 色条改预渲染位图; 温度扫描从主线程
移到 Dispatchers.Default。

标注统一: 新增 AnnotSpec(唯一几何定义) + MarkerPainter(唯一绘制例程), 实时/
分析/照片/视频共用, 极端值标签改用 max/min; 照片按传感器朝向 3x 分辨率保存。
修 placeLabel 不判重叠(min 与 max 印成一团), 现支持让位。

分析对齐: 极端值漏了 sensorToPhoto 映射(落在左上角几十像素内), annotateJpeg
忽略照片镜像(另存时标记镜像到另一侧), 两处已修。

新增 BLOCK_EXTREMES(0x5BB5B562) 存拍摄时的极值位置/温度: 分析页重扫 NUC 不可能
逐位复现 live 结果, 真机出现过两个相距几像素的 min。

分析面板被导航栏遮挡: UiInsets.navPx 改可观察状态并加 padding。

7x7 局部细节增强(官方 FilterDetailEnhancement_Simple 逐行移植), 强度换算
level shl 3 经 MAG_SetDetailEnhancement(钳 0..32)核对一致; 设置页新增
"图像增强" 0-4 级, 默认关闭(无官方参考输出), 不影响逐位基线。

真机验证(小米 22041211AC/Android12/MIUI): 15.1fps、拍照含 2 探针+2 极值、
照片与分析页标记位置/风格一致且各只有一个 min/max、分析数值与照片吻合、
增强 2 级细节明显且不掉帧。测试 96 项全绿。

android/app/src/main/kotlin/com/mag160c/thermal/core/AnnotSpec.kt

@@ -48,8 +48,16 @@ object AnnotSpec {
     fun labelOffsetX(scale: Float): Float = (RING_R + LABEL_GAP) * scale
 
     /**
-     * Where to put a label so it stays inside [imgW]x[imgH].
-     * @return x of the box's left edge and y of the box's top edge
+     * Where to put a label so it stays inside [imgW]x[imgH] and does not sit on
+     * top of an already-placed label.
+     *
+     * @param placed boxes already committed, as [x, y, boxW, boxH]; a candidate
+     *   that intersects one of these is nudged downward (and flipped to the left
+     *   of its marker first if that helps). Without this, two extremes that are
+     *   close together in the scene — the usual case for a hot object against a
+     *   cool background — produced one illegible smear of two overlapping
+     *   temperatures.
+     * @return x of the box's left edge and y of its top edge
      */
     fun placeLabel(
         cx: Float,
@@ -59,6 +67,7 @@ object AnnotSpec {
         imgW: Float,
         imgH: Float,
         scale: Float,
+        placed: List<FloatArray> = emptyList(),
     ): FloatArray {
         val margin = 2f * scale
         var x = cx + labelOffsetX(scale)
@@ -68,6 +77,26 @@ object AnnotSpec {
         var y = cy - boxH / 2f
         if (y < margin) y = margin
         if (y + boxH > imgH - margin) y = imgH - margin - boxH
-        return floatArrayOf(x, y)
+        if (placed.isEmpty()) return floatArrayOf(x, y)
+
+        // Try the flipped side first when the default side is taken: that keeps the
+        // label attached to its own marker instead of sliding away from it.
+        val flippedX = (cx - labelOffsetX(scale) - boxW).coerceAtLeast(margin)
+        val candidates = if (flippedX != x) floatArrayOf(x, flippedX) else floatArrayOf(x)
+        for (candidateX in candidates) {
+            var tryY = y
+            var guard = 0
+            while (guard++ < placed.size + 2) {
+                val hit = placed.firstOrNull {
+                    candidateX < it[0] + it[2] && candidateX + boxW > it[0] &&
+                        tryY < it[1] + it[3] && tryY + boxH > it[1]
+                } ?: return floatArrayOf(candidateX, tryY)
+                // step below the box it hit, staying inside the image
+                tryY = hit[1] + hit[3] + 2f * scale
+                if (tryY + boxH > imgH - margin) break
+            }
+        }
+        // nothing fit cleanly: keep it inside the frame, on the marker's own side
+        return floatArrayOf(x, y.coerceIn(margin, (imgH - margin - boxH).coerceAtLeast(margin)))
     }
 }

android/app/src/main/kotlin/com/mag160c/thermal/core/DetailEnhance.kt

@@ -0,0 +1,150 @@
+package com.mag160c.thermal.core
+
+/**
+ * Local 7x7 detail enhancement, ported from the official native SDK
+ * (`CFunctions::FilterDetailEnhancement_Simple` + `CFunctions::LocalMap7x7_Simple`,
+ * libcxsdk.so; Ghidra listing in
+ * analysis/sdk_re/android_app/libcxsdk_decomp.txt).
+ *
+ * This is the stage that makes the vendor's live image look crisper: for every
+ * pixel it measures the local contrast inside a 7x7 window and pushes the pixel
+ * away from the local mean, so fine texture becomes visible. Our pipeline was
+ * ported from the C reference in `csdk/`, which stops before this filter — that
+ * difference is why the official app looked sharper.
+ *
+ * ## Reading of the decompilation (all offsets are the vendor's own)
+ *
+ * `LocalMap7x7_Simple` samples a 7x7 window at every OTHER pixel (x offsets
+ * 0,2,4,6 and rows stepped by 2 x width, 4 rows = 16 samples), then:
+ *   mean = Σsamples >> 4
+ *   range = max - min
+ *   if (strength <= range * 32):
+ *       divisor = max(max - mean, mean - min, strength)
+ *       detail  = (0x8000 / divisor) * (center - mean)
+ *   else detail = 0
+ * where `center` is the true middle pixel of the window (row 3, col 3), not one of
+ * the 16 samples.
+ *
+ * The driver walks every window position (rows 0..H-7, cols 0..W-7, both stepped
+ * by 1 across the two interleaved loops in the original) and stores the detail at
+ * the window's centre, so each destination pixel receives exactly one value. The
+ * consumer then applies
+ *   gray = clamp(gray + (strength * detail) / 32768, 0, 255)
+ * over the rows/cols the earlier stages actually filled (3..H-4).
+ *
+ * ## Validation status — READ THIS
+ *
+ * The arithmetic above is a faithful transcription, and the structural properties
+ * are unit-tested (`DetailEnhanceTest`), but this port has **no official reference
+ * output to diff against**: the byte-exact `RenderPipelineTest` baseline was built
+ * from the C reference that predates this filter. It is therefore opt-in
+ * ([RenderPipeline.enhanceStrength], default 0 = off) so the verified path stays
+ * the default, and it is exposed as a user-visible toggle rather than silently
+ * changing every image. If it ever looks wrong, turning it off restores the
+ * byte-exact behaviour exactly.
+ */
+class DetailEnhance(private val w: Int, private val h: Int) {
+    private val npix = w * h
+    private val detail = IntArray(npix)
+
+    /**
+     * Apply the filter to [gray] in place.
+     *
+     * @param src16 calibrated 16-bit counts (the pipeline's NUC output)
+     * @param gray 8-bit gray image that the palette stage consumes
+     * @param strength vendor strength parameter (0 = no-op); the official app
+     *   derives it from its enhancement setting as `level shl 3`
+     * @param gain the vendor's `(dev24 * 1000) >> shift` term, clamped to 0xFFFF
+     * @param srcLimit samples beyond this index are read as 0 (the vendor's frame
+     *   buffer can be larger than the active area)
+     */
+    fun enhance(src16: IntArray, gray: ByteArray, strength: Int, gain: Int, srcLimit: Int = src16.size) {
+        if (strength <= 0 || gain <= 0) return
+        require(gray.size >= npix) { "gray buffer smaller than $w x $h" }
+        val k = strength * gain * 2 shr 8
+        if (k == 0) return
+
+        java.util.Arrays.fill(detail, 0)
+
+        // --- pass 1: detail map. The vendor walks rows 0..H-7 in two interleaved
+        // parity loops and stores each window's value at its centre, so every
+        // destination pixel gets exactly one value. ---
+        var row = 0
+        while (row <= h - 7) {
+            var col = 0
+            while (col <= w - 7) {
+                detail[(row + 3) * w + (col + 3)] = localMap(src16, col, row, k, srcLimit)
+                col++
+            }
+            row += 2
+        }
+        var oddRow = 1
+        while (oddRow <= h - 7) {
+            var col = 0
+            while (col <= w - 7) {
+                detail[(oddRow + 3) * w + (col + 3)] = localMap(src16, col, oddRow, k, srcLimit)
+                col++
+            }
+            oddRow += 2
+        }
+
+        // --- pass 2: apply to the gray image (rows 3..H-4, cols 3..W-4 — exactly
+        // the region pass 1 filled) ---
+        var y = 3
+        while (y < h - 3) {
+            var x = 3
+            while (x < w - 3) {
+                val d = detail[y * w + x]
+                if (d != 0) {
+                    // (k * detail) / 32768, truncated toward zero like the vendor
+                    val prod = k * d
+                    val delta = (prod + (if (prod < 0) 0x7FFF else 0)) shr 15
+                    var v = (gray[y * w + x].toInt() and 0xFF) + delta
+                    if (v < 1) v = 0
+                    if (v > 254) v = 255
+                    gray[y * w + x] = v.toByte()
+                }
+                x++
+            }
+            y++
+        }
+    }
+
+    /**
+     * One 7x7 window centred on ([col]+3, [row]+3). Returns the detail value the
+     * vendor's LocalMap7x7_Simple produces, or 0 when the local contrast is below
+     * their `strength <= range * 32` threshold.
+     */
+    private fun localMap(src16: IntArray, col: Int, row: Int, strength: Int, srcLimit: Int): Int {
+        var mn = Int.MAX_VALUE
+        var mx = Int.MIN_VALUE
+        var sum = 0
+        // rows 0,2,4,6 of the window (stride 2 in y), sampling x at 0,2,4,6: the
+        // vendor's 4x4 decimation of the 7x7 neighbourhood
+        var dy = 0
+        while (dy < 4) {
+            val base = (row + dy * 2) * w + col
+            var dx = 0
+            while (dx < 4) {
+                val idx = base + dx * 2
+                val v = if (idx < srcLimit) src16[idx] and 0xFFFF else 0
+                sum += v
+                if (v < mn) mn = v
+                if (v > mx) mx = v
+                dx++
+            }
+            dy++
+        }
+        if (strength <= (mx - mn) * 32) {
+            val mean = sum shr 4
+            var divisor = (mx - mean).coerceAtLeast(strength)
+            divisor = (mean - mn).coerceAtLeast(divisor)
+            if (divisor <= 0) return 0
+            val gain = 0x8000 / divisor
+            val ci = (row + 3) * w + (col + 3)
+            val center = if (ci < srcLimit) src16[ci] and 0xFFFF else 0
+            return gain * (center - mean)
+        }
+        return 0
+    }
+}

android/app/src/main/kotlin/com/mag160c/thermal/core/RenderPipeline.kt

@@ -24,6 +24,15 @@ class RenderPipeline(
     private val force75: Boolean = true,
     /** FFC command callback: param 0 = FFC(0), 1 = FFC(1). */
     private val onFfc: ((param: Int) -> Unit)? = null,
+    /**
+     * Local 7x7 detail enhancement strength (vendor FilterDetailEnhancement_Simple).
+     * 0 = OFF, which keeps the output byte-identical to the verified C reference —
+     * that is the default because this stage is ported from a different source than
+     * the reference baseline and has no official output to diff against (see
+     * [DetailEnhance]). The app exposes it as the "图像增强" setting; the official
+     * app derives its value from its enhancement level as `level shl 3`.
+     */
+    private var enhanceStrength: Int = 0,
 ) {
     private val npix = w * h
 
@@ -77,6 +86,10 @@ class RenderPipeline(
     private var remoteRefWindow = false
 
     private val ref = IntArray(npix)
+
+    /** Local 7x7 detail enhancement (vendor FilterDetailEnhancement_Simple). */
+    private val detailEnhance = DetailEnhance(w, h)
+
     private val refAcc = IntArray(npix)
     private val nuc = IntArray(npix)
     private val gray160 = ByteArray(npix)
@@ -474,6 +487,23 @@ class RenderPipeline(
         pal = Palettes.buildAll()[index.coerceIn(0, Palettes.NAMES.size - 1)]
     }
 
+    /** Detail enhancement strength; 0 disables it (byte-exact reference path). */
+    fun setEnhanceStrength(value: Int) = synchronized(lock) {
+        enhanceStrength = value.coerceIn(0, 64)
+    }
+
+    fun enhanceStrength(): Int = synchronized(lock) { enhanceStrength }
+
+    /**
+     * The vendor's gain term for the enhancement stage: `(dev24 * 1000) >> shift`,
+     * clamped to 0xFFFF (their `this+0x5104` is the shift, which matches
+     * [dev4cShift] in this port).
+     */
+    private fun detailGain(): Int {
+        val g = (dev24 * 1000) shr dev4cShift
+        return if (g > 0xFFFE) 0xFFFF else g
+    }
+
     /** 32-bit unsigned wrap (C unsigned int semantics). */
     private fun u32(x: Long): Long = x and 0xFFFFFFFFL
 
@@ -655,6 +685,10 @@ class RenderPipeline(
         statsWindow()
         lutRebuild()
         grayMap()
+        // vendor order: detail enhancement works on the gray image, before upscale
+        if (enhanceStrength > 0) {
+            detailEnhance.enhance(nuc, gray160, enhanceStrength, detailGain())
+        }
         upscale2x()
         // palette colorize 320x240 -> ARGB
         val pal = this.pal

android/app/src/main/kotlin/com/mag160c/thermal/media/MarkerPainter.kt

@@ -34,6 +34,11 @@ object MarkerPainter {
      * @param imageUnitsToPixels conversion from AnnotSpec units (based on a 320-wide
      *   reference) to target pixels; pass [renderScale] for a photo rendered at
      *   N x the sensor size, or the on-screen scale for a display.
+     * @param textRotationDeg rotate each label about its marker by this angle. The
+     *   live screen passes the negative grip angle so labels stay upright while the
+     *   image is drawn rotated; photos and analysis pass 0, which keeps the text
+     *   horizontal in the sensor frame (the user's requirement for saved files).
+     *   The dot and ring are never rotated.
      */
     fun draw(
         canvas: Canvas,
@@ -41,6 +46,7 @@ object MarkerPainter {
         imgW: Float,
         imgH: Float,
         imageUnitsToPixels: Float,
+        textRotationDeg: Float = 0f,
     ) {
         if (marks.isEmpty()) return
         val k = imageUnitsToPixels
@@ -66,6 +72,11 @@ object MarkerPainter {
         }
         val padH = AnnotSpec.LABEL_PAD_H * k
         val padV = AnnotSpec.LABEL_PAD_V * k
+        // Label boxes committed so far, as [x, y, w, h]: passed to placeLabel so a
+        // second label never lands on the first one. Extremes (max/min) are usually
+        // near each other in the scene, so without this their readouts merged into
+        // an unreadable overlap.
+        val placed = ArrayList<FloatArray>(marks.size)
 
         for (m in marks) {
             val tint = m.tint
@@ -86,8 +97,16 @@ object MarkerPainter {
             // it would overflow) so the photo matches what the user saw
             val pos = com.mag160c.thermal.core.AnnotSpec.placeLabel(
                 cx = m.x, cy = m.y, boxW = boxW, boxH = boxH,
-                imgW = imgW, imgH = imgH, scale = k,
+                imgW = imgW, imgH = imgH, scale = k, placed = placed,
             )
+            placed.add(floatArrayOf(pos[0], pos[1], boxW, boxH))
+            canvas.save()
+            if (textRotationDeg != 0f) {
+                // rotate the LABEL about its marker, keeping it attached: the live
+                // view draws the image rotated, so unrotated text would run down
+                // the screen. The marker glyph itself is never rotated.
+                canvas.rotate(textRotationDeg, m.x, m.y)
+            }
             if (tint == null) {
                 canvas.drawRoundRect(
                     RectF(pos[0], pos[1], pos[0] + boxW, pos[1] + boxH),
@@ -102,6 +121,7 @@ object MarkerPainter {
             val baseline = pos[1] + padV - fm.ascent
             canvas.drawText(full, pos[0] + padH, baseline, text)
             text.clearShadowLayer()
+            canvas.restore()
         }
     }
 

android/app/src/main/kotlin/com/mag160c/thermal/media/Mdt.kt

@@ -16,7 +16,14 @@ import java.io.ByteArrayOutputStream
  *   0x5BB5B55D raw measurement frame (19200 x uint16 LE) — RAW sensor response
  *   0x5BB5B55E text note (UTF-8, optional)
  *   0x5BB5B55F probe points (UTF-8 lines "x,y,label,tempMc", optional)
- *   0x5BB5B560 NUC counts in PHOTO coordinates (19200 x uint16 LE, optional)
+ *   0x5BB5B560 NUC counts on the sensor grid (19200 x uint16 LE, optional)
+ *   0x5BB5B561 render params {u32 version, u32 mirror flags} (optional)
+ *   0x5BB5B562 traced extremes "minPos,maxPos,minMc,maxMc" (optional)
+ *
+ * PROBES/NUC/EXTREMES ARE ALL IN SENSOR SPACE. The JPEG is whatever the user's
+ * mirror settings produced, so a viewer needs [RenderParams] to line a marker up
+ * with a feature in the image; storing markers in photo space instead was the bug
+ * that made analysis markers land mirrored against the burned-in ones.
  *
  * WHY THE NUC BLOCK EXISTS (2026-09-11): the raw frame is the sensor response
  * BEFORE non-uniformity correction, so converting it directly yields nonsense
@@ -36,20 +43,113 @@ object Mdt {
     const val BLOCK_TXT = 0x5BB5B55E
 
     /**
-     * Probe points captured with the photo, in the SAVED PHOTO's pixel
-     * coordinates (not sensor coordinates — that mismatch put the markers in the
-     * wrong place when the photo was displayed). Stored as UTF-8 text
-     * ("x,y,label,tempMc" per line) so the values stay inspectable with any hex
-     * editor — the same reasoning the vendor layout uses for its TXT section.
+     * Probe points captured with the photo, in SENSOR pixel coordinates (0..159,
+     * 0..119). Sensor space, not photo space: the photo carries the user's mirror
+     * corrections while the probes must stay in the frame the temperature data
+     * lives in, so a viewer applies [RenderParams] to place them (see [BLOCK_NUC]).
+     * Stored as UTF-8 text ("x,y,label,tempMc" per line) so the values stay
+     * inspectable with any hex editor — the same reasoning the vendor layout uses
+     * for its TXT section.
      */
     const val BLOCK_PROBES = 0x5BB5B55F
 
-    /** NUC (calibrated) counts in photo pixel order; see the header note. */
+    /**
+     * NUC (calibrated) counts on the 160x120 SENSOR grid (19200 x uint16 LE), the
+     * same space as [BLOCK_PROBES]; see the header note. Because the sensor grid is
+     * 160 wide and a sensor pixel is exactly two AnnotSpec units, the offline
+     * temperature lookup is a single index — no resampling.
+     */
     const val BLOCK_NUC = 0x5BB5B560
 
+    /**
+     * How the JPEG was rendered: {u32 version, u32 flags}.
+     *
+     * Flags: bit0 = mirrored horizontally, bit1 = mirrored vertically (the user's
+     * sensor-mount corrections). Stored because the photo carries those flips while
+     * the probe coordinates and the NUC grid are in raw SENSOR space — a viewer
+     * that ignores this draws the markers at mirrored positions, which is exactly
+     * the misalignment reported on device (analysis markers did not sit on the
+     * marks visible in the photo).
+     */
+    const val BLOCK_RENDER = 0x5BB5B561
+
+    /**
+     * The max/min the capture recorded, in SENSOR coordinates:
+     * "minX,minY,minMc,maxX,maxY,maxMc" (UTF-8 text, like the probe block).
+     *
+     * Stored because the analysis screen otherwise re-derives the extremes from
+     * the NUC block, and it cannot get the same answer: the live scan and the
+     * offline scan disagree by a temperature step and several pixels whenever the
+     * sensor drifts between the capture and the reload (the argmin of a noisy flat
+     * region moves easily). On device this showed as TWO min markers a few pixels
+     * apart with 22.0 and 22.1 C — the one burned into the JPEG and the one the
+     * analysis had just recomputed. With this block the analysis draws exactly the
+     * marker the photo already carries.
+     */
+    const val BLOCK_EXTREMES = 0x5BB5B562
+
+    const val RENDER_FLAG_FLIP_H = 1
+    const val RENDER_FLAG_FLIP_V = 2
+
     /** One probe carried in an MDT file. */
     data class Probe(val x: Int, val y: Int, val label: String, val tempMc: Int)
 
+    /** Render parameters recorded with the photo. */
+    data class RenderParams(val flipH: Boolean, val flipV: Boolean) {        val flags: Int
+            get() = (if (flipH) RENDER_FLAG_FLIP_H else 0) or
+                (if (flipV) RENDER_FLAG_FLIP_V else 0)
+
+        companion object {
+            val NONE = RenderParams(false, false)
+
+            fun fromFlags(flags: Int): RenderParams =
+                RenderParams(flags and RENDER_FLAG_FLIP_H != 0, flags and RENDER_FLAG_FLIP_V != 0)
+        }
+    }
+
+    fun encodeRenderParams(p: RenderParams): ByteArray {
+        val out = ByteArray(8)
+        put32(out, 0, 1)
+        put32(out, 4, p.flags)
+        return out
+    }
+
+    fun parseRenderParams(bytes: ByteArray?): RenderParams {
+        if (bytes == null || bytes.size < 8) return RenderParams.NONE
+        return RenderParams.fromFlags(u32(bytes, 4))
+    }
+
+    /**
+     * The capture's max/min in sensor coordinates. [minPos]/[maxPos] are sensor
+     * indices (y*160+x), matching what the live view published.
+     */
+    data class Extremes(
+        val minPos: Int,
+        val maxPos: Int,
+        val minMc: Int,
+        val maxMc: Int,
+    ) {
+        companion object {
+            /** Sentinel for "the capture did not trace any extreme". */
+            val NONE = Extremes(-1, -1, 0, 0)
+            val hasAny: (Extremes) -> Boolean = { it.minPos >= 0 || it.maxPos >= 0 }
+        }
+    }
+
+    fun encodeExtremes(e: Extremes): ByteArray =
+        "${e.minPos},${e.maxPos},${e.minMc},${e.maxMc}".toByteArray(Charsets.UTF_8)
+
+    fun parseExtremes(bytes: ByteArray?): Extremes {
+        if (bytes == null || bytes.isEmpty()) return Extremes.NONE
+        val parts = String(bytes, Charsets.UTF_8).trimEnd('\u0000').split(',')
+        if (parts.size < 4) return Extremes.NONE
+        val mn = parts[0].trim().toIntOrNull() ?: return Extremes.NONE
+        val mx = parts[1].trim().toIntOrNull() ?: return Extremes.NONE
+        val mnMc = parts[2].trim().toIntOrNull() ?: return Extremes.NONE
+        val mxMc = parts[3].trim().toIntOrNull() ?: return Extremes.NONE
+        return Extremes(mn, mx, mnMc, mxMc)
+    }
+
     fun encodeProbes(probes: List<Probe>): ByteArray =
         probes.joinToString("\n") { "${it.x},${it.y},${it.label},${it.tempMc}" }
             .toByteArray(Charsets.UTF_8)
@@ -99,6 +199,8 @@ object Mdt {
         text: ByteArray? = null,
         probes: ByteArray? = null,
         nucPixels: ByteArray? = null,
+        renderParams: ByteArray? = null,
+        extremes: ByteArray? = null,
     ): ByteArray {
         val out = ByteArrayOutputStream(align4(jpg.size) + 0x88 + 38400 + 320)
         out.write(jpg, 0, jpg.size)
@@ -129,6 +231,8 @@ object Mdt {
         nucPixels?.let {
             if (it.size >= 38400 && it.size % 2 == 0) emit(BLOCK_NUC, it)
         }
+        renderParams?.let { emit(BLOCK_RENDER, it) }
+        extremes?.let { if (it.isNotEmpty()) emit(BLOCK_EXTREMES, it) }
 
         val bodyBytes = body.toByteArray()
         val header = ByteArray(0x88)
@@ -176,6 +280,8 @@ object Mdt {
             text = blocks[BLOCK_TXT]?.let { String(it, Charsets.UTF_8).trimEnd('\u0000') },
             probes = parseProbes(blocks[BLOCK_PROBES]),
             nucPixels = blocks[BLOCK_NUC],
+            render = parseRenderParams(blocks[BLOCK_RENDER]),
+            extremes = parseExtremes(blocks[BLOCK_EXTREMES]),
         )
     }
 
@@ -215,6 +321,16 @@ object Mdt {
          * computing wrong ones.
          */
         val nucPixels: ByteArray? = null,
+        /**
+         * How the JPEG was mirrored. Markers and the NUC grid are in raw SENSOR
+         * space, so a viewer must apply this to line them up with the image.
+         */
+        val render: RenderParams = RenderParams.NONE,
+        /**
+         * The max/min the capture recorded, when it traced any. Preferred over
+         * re-scanning [nucPixels]: see [BLOCK_EXTREMES].
+         */
+        val extremes: Extremes = Extremes.NONE,
     ) {
         /** True when this photo can be measured offline. */
         val hasTemperatureData: Boolean get() = nucPixels != null

android/app/src/main/kotlin/com/mag160c/thermal/media/PhotoSaver.kt

@@ -120,7 +120,15 @@ object PhotoSaver {
             val pos = sensorToPhoto(p.x, p.y, mirror, outW, outH)
             marks.add(MarkerPainter.Mark(pos[0], pos[1], p.label, p.tempC))
         }
-        marks.addAll(extremes)
+        // The extremes arrive in SENSOR coordinates (same space as the probes) and
+        // must go through the same mapping. Adding them raw put both markers in the
+        // photo's top-left corner: sensor x/y are 0..159/0..119, so on a 960x720
+        // photo they landed within a few dozen pixels of the origin instead of over
+        // the hot/cold spots they name.
+        for (e in extremes) {
+            val pos = sensorToPhoto(e.x.toInt(), e.y.toInt(), mirror, outW, outH)
+            marks.add(MarkerPainter.Mark(pos[0], pos[1], e.label, e.tempC, e.tint))
+        }
         if (marks.isNotEmpty()) {
             // AnnotSpec units are calibrated for a 320-wide image; the photo is
             // RENDER_SCALE x that (times any extra upscale), so text stays sharp
@@ -201,22 +209,30 @@ object PhotoSaver {
     fun annotateJpeg(
         jpg: ByteArray,
         marks: List<MarkerPainter.Mark>,
+        mirror: Mirror = Mirror(false, false),
     ): ByteArray {
         if (marks.isEmpty()) return jpg
         val bmp = android.graphics.BitmapFactory.decodeByteArray(jpg, 0, jpg.size) ?: return jpg
         val out = bmp.copy(Bitmap.Config.ARGB_8888, true) ?: return jpg
-        // marks arrive in SENSOR coordinates; the bitmap may be larger
-        val pxPerSensor = out.width / 160f
+        // marks arrive in SENSOR coordinates; the bitmap is the saved photo, which
+        // carries the capture's mirror. Converting through sensorToPhoto keeps them
+        // on the same features the photo shows — without it, saving from the
+        // analysis screen put every marker on the mirrored side of the image.
+        val pxPerSensorX = out.width / 160f
         val scaled = marks.map {
-            MarkerPainter.Mark(it.x * pxPerSensor, it.y * pxPerSensor, it.label, it.tempC, it.tint)
+            val pos = sensorToPhoto(
+                it.x.toInt().coerceIn(0, 159), it.y.toInt().coerceIn(0, 119),
+                mirror, out.width, out.height,
+            )
+            MarkerPainter.Mark(pos[0], pos[1], it.label, it.tempC, it.tint)
         }
         MarkerPainter.draw(
             canvas = Canvas(out),
             marks = scaled,
             imgW = out.width.toFloat(),
             imgH = out.height.toFloat(),
-            // AnnotSpec units are calibrated for a 320-wide frame = 2 sensor units
-            imageUnitsToPixels = out.width / 320f,
+            // AnnotSpec units are calibrated for a 320-wide frame = 2 sensor pixels
+            imageUnitsToPixels = pxPerSensorX / 2f,
         )
         return encodeJpeg(out)
     }

android/app/src/main/kotlin/com/mag160c/thermal/ui/DeviceOrientation.kt

@@ -52,6 +52,16 @@ object DeviceOrientation : SensorEventListener {
     override fun onSensorChanged(event: SensorEvent) {
         val gx = event.values[0]
         val gy = event.values[1]
+        // Lying (nearly) flat: gx and gy are both ~0, so the grip angle is
+        // undefined and the hysteresis below would keep whatever pose was seen
+        // last. That is how the live screen ended up with all OSD text rotated 90
+        // deg while the phone sat flat on a desk. Flat means "read it as drawn":
+        // the composition is glued to the portrait frame, so 0 is the honest value.
+        // 4.0 m/s^2 ~= within 24 deg of horizontal.
+        if (kotlin.math.hypot(gx, gy) < FLAT_TILT_MS2) {
+            if (_deg.value != 0) _deg.value = 0
+            return
+        }
         // world-up in device coords: (0,+g)=0  (-g,0)=90  (0,-g)=180  (+g,0)=270.
         // hysteresis: only switch pose when the dominant axis clearly wins,
         // so ~45 deg in-between holds keep the previous reading
@@ -64,4 +74,6 @@ object DeviceOrientation : SensorEventListener {
     }
 
     override fun onAccuracyChanged(sensor: Sensor?, accuracy: Int) = Unit
+
+    private const val FLAT_TILT_MS2 = 4.0f
 }

android/app/src/main/kotlin/com/mag160c/thermal/ui/UiInsets.kt

@@ -1,8 +1,19 @@
 package com.mag160c.thermal.ui
 
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.setValue
+
 /** Shared UI inset state (px), written by AppRoot's nav overlay. */
 object UiInsets {
-    /** Bottom navigation overlay height in px (portrait-locked app: constant). */
-    @Volatile
-    var navPx: Int = 0
+    /**
+     * Bottom navigation overlay height in px (portrait-locked app: constant).
+     *
+     * Observable, not a plain var: the full-screen overlays (analysis viewer,
+     * album photo viewer) place their own bottom panel above this bar, and a
+     * non-observable value read during composition would stay at whatever it was
+     * on the first frame — which is 0, leaving the analysis readouts behind the
+     * navigation bar where the user could not see them.
+     */
+    var navPx: Int by mutableStateOf(0)
 }

android/app/src/main/kotlin/com/mag160c/thermal/ui/analyze/AnalyzeViewModel.kt

@@ -87,6 +87,7 @@ class AnalyzeViewModel(
                 _imageH.value = bmp.height
             }
             val counts = nucCounts
+            val recorded = parsed?.extremes ?: com.mag160c.thermal.media.Mdt.Extremes.NONE
             var mn = Int.MAX_VALUE
             var mx = Int.MIN_VALUE
             var mnPos = -1
@@ -95,8 +96,14 @@ class AnalyzeViewModel(
                 if (v < mn) { mn = v; mnPos = i }
                 if (v > mx) { mx = v; mxPos = i }
             }
+            // Prefer the extremes the CAPTURE recorded. Re-scanning the NUC block
+            // gives a slightly different answer (a different pixel and a step of
+            // temperature, because the sensor drifts between capture and reload),
+            // which showed up on device as two "min" markers a few pixels apart.
+            if (recorded.minPos >= 0) mnPos = recorded.minPos
+            if (recorded.maxPos >= 0) mxPos = recorded.maxPos
             val loaded = (parsed?.probes.orEmpty()).map { p ->
-                Probe(p.x, p.y, p.label, measure(p.x, p.y) ?: (p.tempMc / 1000f))
+                Probe(p.x, p.y, p.label, measureSensor(p.x, p.y) ?: (p.tempMc / 1000f))
             }
             withContext(Dispatchers.Main) {
                 _render.value = bmp
@@ -104,12 +111,22 @@ class AnalyzeViewModel(
                 probes.addAll(loaded)
                 if (counts != null) {
                     // mn/mx are NUC counts and must go through the temperature
-                    // curve; dividing them directly showed 9 C for a 23 C scene
-                    _minTempC.value = TempMath.countsToTempMc(mn) / 1000f
-                    _maxTempC.value = TempMath.countsToTempMc(mx) / 1000f
+                    // curve; dividing them directly showed 9 C for a 23 C scene.
+                    // A recorded extreme is already a temperature (millidegrees),
+                    // so it is used as-is — the two units must not be mixed.
+                    _minTempC.value = if (recorded.minPos >= 0 && recorded.minMc != 0) {
+                        recorded.minMc / 1000f
+                    } else if (mn != Int.MAX_VALUE) {
+                        TempMath.countsToTempMc(mn) / 1000f
+                    } else null
+                    _maxTempC.value = if (recorded.maxPos >= 0 && recorded.maxMc != 0) {
+                        recorded.maxMc / 1000f
+                    } else if (mx != Int.MIN_VALUE) {
+                        TempMath.countsToTempMc(mx) / 1000f
+                    } else null
                     _minPos.value = mnPos
                     _maxPos.value = mxPos
-                    _centerTempC.value = measure(80, 60)
+                    _centerTempC.value = measureSensor(80, 60)
                 }
                 com.mag160c.thermal.media.DebugLog.log(
                     "analyze",
@@ -121,11 +138,46 @@ class AnalyzeViewModel(
         }
     }
 
+    /** Mirror applied to the saved JPEG (from the container). */
+    val photoMirror: PhotoSaver.Mirror
+        get() {
+            val r = parsed?.render ?: Mdt.RenderParams.NONE
+            return PhotoSaver.Mirror(r.flipH, r.flipV)
+        }
+
     /**
-     * Temperature (C) at a SENSOR pixel, from the stored NUC counts.
-     * Returns null when the photo has no NUC data — never a fabricated number.
+     * Sensor pixel -> photo pixel for the DISPLAYED image.
+     *
+     * The JPEG carries the user's mirror corrections while probes and the NUC grid
+     * stay in raw sensor space, so this conversion is what keeps markers sitting on
+     * the same spot the live screen showed. Ignoring it was the reported
+     * misalignment.
      */
-    fun measure(sx: Int, sy: Int): Float? {
+    private fun sensorToPhoto(px: Int, py: Int): Pair<Int, Int> {
+        val m = photoMirror
+        val w = _imageW.value
+        val h = _imageH.value
+        var u = (px + 0.5f) / 160f
+        var v = (py + 0.5f) / 120f
+        if (m.flipH) u = 1f - u
+        if (m.flipV) v = 1f - v
+        return ((u * w).toInt().coerceIn(0, w - 1)) to ((v * h).toInt().coerceIn(0, h - 1))
+    }
+
+    /** Inverse of [sensorToPhoto]: a photo pixel back to sensor coordinates. */
+    private fun photoToSensor(px: Int, py: Int): Pair<Int, Int> {
+        val m = photoMirror
+        val w = _imageW.value
+        val h = _imageH.value
+        var u = (px + 0.5f) / w
+        var v = (py + 0.5f) / h
+        if (m.flipH) u = 1f - u
+        if (m.flipV) v = 1f - v
+        return ((u * 160f).toInt().coerceIn(0, 159)) to ((v * 120f).toInt().coerceIn(0, 119))
+    }
+
+    /** Temperature (C) at a SENSOR pixel, from the stored NUC counts. */
+    fun measureSensor(sx: Int, sy: Int): Float? {
         val counts = nucCounts ?: return null
         if (sx < 0 || sy < 0 || sx >= 160 || sy >= 120) return null
         val idx = sy * 160 + sx
@@ -133,18 +185,27 @@ class AnalyzeViewModel(
         return TempMath.countsToTempMc(counts[idx]) / 1000f
     }
 
-    /** Tap in canvas space -> sensor pixel; toggles a probe there. */
+    /** Temperature (C) at a pixel of the DISPLAYED photo. */
+    fun measure(px: Int, py: Int): Float? {
+        val s = photoToSensor(px, py)
+        return measureSensor(s.first, s.second)
+    }
+
+    /** Tap in canvas space -> SENSOR pixel; toggles a probe there. */
     fun toggleProbeAt(
         pos: androidx.compose.ui.geometry.Offset,
         rect: androidx.compose.ui.geometry.Rect,
     ) {
         if (rect.width <= 0f || rect.height <= 0f) return
         if (pos.x < rect.left || pos.x > rect.right || pos.y < rect.top || pos.y > rect.bottom) return
-        // the photo has no rotation relative to the sensor: a uniform scale
-        val sx = ((pos.x - rect.left) / rect.width * 160f).toInt().coerceIn(0, 159)
-        val sy = ((pos.y - rect.top) / rect.height * 120f).toInt().coerceIn(0, 119)
+        val photoX = ((pos.x - rect.left) / rect.width * _imageW.value).toInt()
+            .coerceIn(0, _imageW.value - 1)
+        val photoY = ((pos.y - rect.top) / rect.height * _imageH.value).toInt()
+            .coerceIn(0, _imageH.value - 1)
+        val (sx, sy) = photoToSensor(photoX, photoY)
 
-        val thr = 6f   // ~6 sensor pixels, matching the on-screen marker size
+        // markers are ~6 sensor pixels across on screen; match that when hit-testing
+        val thr = 6f
         val hit = probes.indexOfFirst { p ->
             val dx = (p.x - sx).toFloat()
             val dy = (p.y - sy).toFloat()
@@ -154,7 +215,7 @@ class AnalyzeViewModel(
             probes.removeAt(hit)
             return
         }
-        probes.add(Probe(sx, sy, "Pt${probes.size + 1}", measure(sx, sy) ?: 0f))
+        probes.add(Probe(sx, sy, "Pt${probes.size + 1}", measureSensor(sx, sy) ?: 0f))
     }
 
     /** Current probes as markers (sensor space), for burning into a saved copy. */
@@ -184,7 +245,7 @@ class AnalyzeViewModel(
         }
         viewModelScope.launch(Dispatchers.IO) {
             val jpg = PhotoSaver.encodeJpeg(bmp, quality = 92)
-            val annotated = PhotoSaver.annotateJpeg(jpg, probesAsMarks())
+            val annotated = PhotoSaver.annotateJpeg(jpg, probesAsMarks(), photoMirror)
             val mdt = Mdt.compose(
                 jpg = annotated,
                 info0 = parsed?.info0,
@@ -196,6 +257,14 @@ class AnalyzeViewModel(
                 ),
                 // carry the temperature data forward so the edited photo stays measurable
                 nucPixels = parsed?.nucPixels,
+                renderParams = com.mag160c.thermal.media.Mdt.encodeRenderParams(
+                    com.mag160c.thermal.media.Mdt.RenderParams(photoMirror.flipH, photoMirror.flipV),
+                ),
+                // the extremes are burned into the pixels already; keep the block so
+                // the next reader still knows where they were
+                extremes = parsed?.extremes?.takeIf {
+                    com.mag160c.thermal.media.Mdt.Extremes.hasAny(it)
+                }?.let { com.mag160c.thermal.media.Mdt.encodeExtremes(it) },
             )
             val name = "MAG160C_${java.text.SimpleDateFormat("yyyyMMdd_HHmmss", Locale.US)
                 .format(java.util.Date())}_edit.jpg"
@@ -219,6 +288,12 @@ class AnalyzeViewModel(
                     probes.map { Mdt.Probe(it.x, it.y, it.label, (it.tempC * 1000).toInt()) },
                 ),
                 nucPixels = parsed?.nucPixels,
+                renderParams = com.mag160c.thermal.media.Mdt.encodeRenderParams(
+                    com.mag160c.thermal.media.Mdt.RenderParams(photoMirror.flipH, photoMirror.flipV),
+                ),
+                extremes = parsed?.extremes?.takeIf {
+                    com.mag160c.thermal.media.Mdt.Extremes.hasAny(it)
+                }?.let { com.mag160c.thermal.media.Mdt.encodeExtremes(it) },
             )
             val ok = runCatching {
                 val ctx = getApplication<Application>()

android/app/src/main/kotlin/com/mag160c/thermal/ui/analyze/AnalyzeViewer.kt

@@ -46,6 +46,7 @@ import androidx.compose.ui.unit.IntSize
 import androidx.compose.ui.unit.dp
 import androidx.compose.ui.unit.sp
 import com.mag160c.thermal.core.Palettes
+import com.mag160c.thermal.media.PhotoSaver
 import com.mag160c.thermal.ui.gallery.GalleryViewModel
 import java.util.Locale
 
@@ -92,7 +93,18 @@ fun AnalyzeViewer(
     // back gesture (reported on device).
     androidx.activity.compose.BackHandler(enabled = true) { onClose() }
 
-    Column(modifier = Modifier.fillMaxSize().background(Color(0xFF101014))) {
+    // The viewer is a full-screen overlay ABOVE the navigation bar, so it must
+    // reserve the bar's height itself — otherwise the measurement panel ends up
+    // behind the bar and the readouts are invisible (reported on device).
+    val navPad = with(androidx.compose.ui.platform.LocalDensity.current) {
+        com.mag160c.thermal.ui.UiInsets.navPx.toDp()
+    }
+    Column(
+        modifier = Modifier
+            .fillMaxSize()
+            .background(Color(0xFF101014))
+            .padding(bottom = navPad),
+    ) {
         // ---- slim title row ----
         Row(
             modifier = Modifier.fillMaxWidth().padding(horizontal = 4.dp, vertical = 2.dp),
@@ -159,12 +171,31 @@ fun AnalyzeViewer(
                         ),
                         dstSize = IntSize(rect.width.toInt(), rect.height.toInt()),
                     )
-                    // extremes, only when the photo carries temperature data
+                    // extremes and probes go into ONE painter call: the painter
+                    // avoids putting a label on top of an earlier one, and that only
+                    // works if it sees every marker at once (drawing the extremes in
+                    // separate calls let "max" and "min" land on each other here).
+                    val marks = ArrayList<com.mag160c.thermal.media.MarkerPainter.Mark>(4)
                     if (vm.hasTemperatureData) {
-                        drawExtreme(vm.maxPos, rect, vm.imageW, vm.imageH, "高")
-                        drawExtreme(vm.minPos, rect, vm.imageW, vm.imageH, "低")
+                        sensorMark(vm.maxPos, rect, vm.photoMirror, "max", vm.maxTempC)?.let { marks.add(it) }
+                        sensorMark(vm.minPos, rect, vm.photoMirror, "min", vm.minTempC)?.let { marks.add(it) }
+                    }
+                    marks.addAll(probeMarks(vm.probes, rect, vm.photoMirror))
+                    if (marks.isNotEmpty()) {
+                        // AnnotSpec units are calibrated for a 320-wide frame =
+                        // 2 sensor pixels, so the display scale factor is half the
+                        // per-sensor-pixel size.
+                        val k = (rect.width / 160f) / 2f
+                        drawIntoCanvas { c ->
+                            com.mag160c.thermal.media.MarkerPainter.draw(
+                                canvas = c.nativeCanvas,
+                                marks = marks,
+                                imgW = size.width,
+                                imgH = size.height,
+                                imageUnitsToPixels = k,
+                            )
+                        }
                     }
-                    drawProbes(vm.probes, rect, vm.imageW, vm.imageH)
                 }
             }
         }
@@ -284,106 +315,71 @@ private fun imageRect(
 }
 
 /**
- * Marker geometry on screen. Delegates to [com.mag160c.thermal.core.AnnotSpec] so
- * the on-screen marker has the SAME size and label placement as the burned-in
- * photo and video markers (previously each surface had its own numbers, which is
- * why a probe looked different in the photo than on the screen).
+ * Markers for the analysis view.
+ *
+ * Delegates to [com.mag160c.thermal.media.MarkerPainter] — the very same painter
+ * that burns markers into saved photos and recorded video frames — so a probe is
+ * rendered identically everywhere. Hand-drawing here is what made the on-screen
+ * marker differ from the one in the file.
+ *
+ * Positions are converted from sensor space through the photo's mirror so the
+ * marker sits on the same feature the photo shows. The marks are returned rather
+ * than drawn so the caller can hand the painter ALL of them at once, which is
+ * what lets it keep their labels from overlapping.
  */
-private fun DrawScope.drawProbes(
+private fun probeMarks(
     probes: List<AnalyzeViewModel.Probe>,
     rect: androidx.compose.ui.geometry.Rect,
-    imageW: Int,
-    imageH: Int,
-) {
-    if (probes.isEmpty()) return
-    val spec = com.mag160c.thermal.core.AnnotSpec
-    // sensor pixel -> screen pixel, then AnnotSpec units are based on a 320-wide
-    // frame (2 sensor units), hence the /2
-    val pxPerSensor = rect.width / 160f
-    val k = pxPerSensor / 2f
-    val paint = android.graphics.Paint().apply {
-        color = spec.LABEL_FG
-        textSize = spec.TEXT_SIZE * k
-        typeface = android.graphics.Typeface.create(
-            android.graphics.Typeface.SANS_SERIF, android.graphics.Typeface.BOLD,
+    mirror: PhotoSaver.Mirror,
+): List<com.mag160c.thermal.media.MarkerPainter.Mark> =
+    probes.map { p ->
+        val (u, v) = sensorToDisplay(p.x, p.y, mirror)
+        com.mag160c.thermal.media.MarkerPainter.Mark(
+            x = rect.left + u * rect.width,
+            y = rect.top + v * rect.height,
+            label = p.label,
+            tempC = p.tempC,
         )
-        isAntiAlias = true
     }
-    val boxPaint = android.graphics.Paint().apply {
-        color = spec.LABEL_BG
-        isAntiAlias = true
-    }
-    val dot = android.graphics.Paint().apply {
-        color = android.graphics.Color.WHITE
-        isAntiAlias = true
-        setShadowLayer(spec.SHADOW * k, 0f, 0f, android.graphics.Color.BLACK)
-    }
-    val ring = android.graphics.Paint().apply {
-        color = android.graphics.Color.WHITE
-        style = android.graphics.Paint.Style.STROKE
-        strokeWidth = spec.RING_W * k
-        isAntiAlias = true
-        setShadowLayer(spec.SHADOW * k, 0f, 0f, android.graphics.Color.BLACK)
-    }
-    for (p in probes) {
-        val cx = rect.left + (p.x + 0.5f) * pxPerSensor
-        val cy = rect.top + (p.y + 0.5f) * pxPerSensor
-        drawCircle(Color.White, spec.DOT_R * k, Offset(cx, cy))
-        drawCircle(Color.White, spec.RING_R * k, Offset(cx, cy), style = Stroke(spec.RING_W * k))
-        drawIntoCanvas { c -> c.nativeCanvas.drawCircle(cx, cy, spec.RING_R * k, ring) }
-        val label = "${p.label} ${"%.1f℃".format(Locale.US, p.tempC)}"
-        val fm = paint.fontMetrics
-        val tw = paint.measureText(label)
-        val boxW = tw + spec.LABEL_PAD_H * 2 * k
-        val boxH = (fm.descent - fm.ascent) + spec.LABEL_PAD_V * 2 * k
-        val pos = spec.placeLabel(
-            cx, cy, boxW, boxH, size.width, size.height, k,
-        )
-        drawIntoCanvas { c ->
-            c.nativeCanvas.drawRoundRect(
-                android.graphics.RectF(pos[0], pos[1], pos[0] + boxW, pos[1] + boxH),
-                2f * k, 2f * k, boxPaint,
-            )
-            c.nativeCanvas.drawText(
-                label, pos[0] + spec.LABEL_PAD_H * k,
-                pos[1] + spec.LABEL_PAD_V * k - fm.ascent, paint,
-            )
-        }
-    }
-}
 
-/** Small ring marking an overall extreme (max/min) position. */
-private fun DrawScope.drawExtreme(
+/**
+ * Overall max/min marker: the same glyph as a probe, tinted, labelled "max"/"min"
+ * (the user asked for these exact names rather than the previous 高/低 wording).
+ */
+private fun sensorMark(
     pos: Int,
     rect: androidx.compose.ui.geometry.Rect,
-    imageW: Int,
-    imageH: Int,
+    mirror: PhotoSaver.Mirror,
     label: String,
-) {
-    if (pos < 0) return
+    tempC: Float?,
+): com.mag160c.thermal.media.MarkerPainter.Mark? {
+    if (pos < 0 || tempC == null) return null
     val sx = pos % 160
     val sy = pos / 160
-    if (sy >= 120) return
-    val spec = com.mag160c.thermal.core.AnnotSpec
-    val pxPerSensor = rect.width / 160f
-    val k = pxPerSensor / 2f
-    val cx = rect.left + (sx + 0.5f) * pxPerSensor
-    val cy = rect.top + (sy + 0.5f) * pxPerSensor
-    drawCircle(
-        Color(spec.EXTREME_TINT), spec.RING_R * 0.9f * k, Offset(cx, cy),
-        style = Stroke(spec.RING_W * k),
+    if (sy >= 120) return null
+    val (u, v) = sensorToDisplay(sx, sy, mirror)
+    return com.mag160c.thermal.media.MarkerPainter.Mark(
+        x = rect.left + u * rect.width,
+        y = rect.top + v * rect.height,
+        label = label,
+        tempC = tempC,
+        tint = com.mag160c.thermal.core.AnnotSpec.EXTREME_TINT,
     )
-    val paint = android.graphics.Paint().apply {
-        color = spec.EXTREME_TINT
-        textSize = spec.TEXT_SIZE * k
-        isAntiAlias = true
-        setShadowLayer(spec.SHADOW * k, 0f, 0f, android.graphics.Color.BLACK)
-    }
-    drawIntoCanvas { c ->
-        c.nativeCanvas.drawText(
-            label, cx + spec.RING_R * 1.2f * k, cy - spec.RING_R * 0.4f * k, paint,
-        )
-    }
+}
+
+/**
+ * Sensor pixel -> normalised (0..1) position in the DISPLAYED photo, applying the
+ * mirror the capture baked into the file. The pixel CENTRE is used (sx + 0.5), so
+ * a marker lands on the middle of the sensor pixel rather than its corner — the
+ * half-pixel offset is what made analysis markers look shifted by up to a pixel
+ * against the burned-in ones.
+ */
+private fun sensorToDisplay(sx: Int, sy: Int, mirror: PhotoSaver.Mirror): Pair<Float, Float> {
+    var u = (sx + 0.5f) / 160f
+    var v = (sy + 0.5f) / 120f
+    if (mirror.flipH) u = 1f - u
+    if (mirror.flipV) v = 1f - v
+    return u to v
 }
 
 /** Current canvas size, captured for the tap handler. */

android/app/src/main/kotlin/com/mag160c/thermal/ui/live/LiveRenderer.kt

@@ -9,6 +9,7 @@ import android.os.SystemClock
 import android.view.SurfaceHolder
 import android.view.SurfaceView
 import com.mag160c.thermal.core.AnnotSpec
+import java.util.Locale
 
 /**
  * Software canvas renderer for the live IR stream.
@@ -29,6 +30,31 @@ class LiveRenderer(
 ) : SurfaceHolder.Callback, Runnable {
     private var thread: Thread? = null
     private val running = java.util.concurrent.atomic.AtomicBoolean(false)
+
+    /**
+     * Hardware canvas when the platform has one, software otherwise.
+     *
+     * This is THE stutter fix. `SurfaceHolder.lockCanvas()` hands out a software
+     * canvas, so every frame upscaled the 320x240 image to the fitted rect
+     * (~810x1080) with a CPU bilinear filter and cleared a ~10 MB buffer by hand —
+     * measured on the device: 6.5 paints/second at 134 ms each, i.e. the render
+     * thread threw away more than half of the camera's 15 fps before the user ever
+     * saw them. A hardware canvas does the same scale-up on the GPU (and the
+     * surface clear for free), leaving the CPU with only the 76800-pixel copy.
+     *
+     * `lockHardwareCanvas` exists from API 29; on older devices the software path
+     * is kept, which is correct, just slower.
+     */
+    private val useHardwareCanvas = android.os.Build.VERSION.SDK_INT >= 29
+
+    private fun lockCanvas(holder: SurfaceHolder): Canvas? {
+        if (useHardwareCanvas) {
+            val hw = runCatching { holder.lockHardwareCanvas() }.getOrNull()
+            if (hw != null) return hw
+        }
+        return runCatching { holder.lockCanvas() }.getOrNull()
+    }
+
     private val density = surfaceView.resources.displayMetrics.density
     private val bitmap = Bitmap.createBitmap(320, 240, Bitmap.Config.ARGB_8888)
     private val paint = Paint(Paint.FILTER_BITMAP_FLAG)
@@ -44,6 +70,26 @@ class LiveRenderer(
     }
     private val viewport = android.graphics.RectF()
 
+    /**
+     * Scratch buffers owned by the render thread.
+     *
+     * Per-frame allocation is what makes a stream feel "卡": at 15 fps a fresh
+     * 320x240 IntArray is 4.6 MB/s of garbage, and the collector's pauses land
+     * exactly on the frames the user is watching. The flipped frame, the marker
+     * list and the colour-bar segments are all recycled instead.
+     */
+    private val flipped = IntArray(320 * 240)
+    private val marks = ArrayList<com.mag160c.thermal.media.MarkerPainter.Mark>(8)
+    private val barPaint = Paint()
+    private val srcRect = android.graphics.Rect()
+    private val dstRect = android.graphics.RectF()
+    private var barBitmap: Bitmap? = null
+    private var barPaletteIdx = -1
+
+    private companion object {
+        const val BAR_SEGMENTS = 96
+    }
+
     /** OSD text compensation: pre-rotation so labels are upright in the current grip. */
     private val textRot: Float
         get() = -com.mag160c.thermal.ui.DeviceOrientation.deg.value.toFloat()
@@ -74,6 +120,10 @@ class LiveRenderer(
         val holder = surfaceView.holder
         var lastPainted = 0L
         var lastPaintMs = 0L
+        var paints = 0
+        var paintT0 = SystemClock.elapsedRealtime()
+        var paintMsTotal = 0L
+        var worstPaintMs = 0L
         while (running.get()) {
             // Skip frames when nothing new arrived: the camera runs at 15 fps and
             // the loop used to paint at 30 fps regardless, doubling the canvas work
@@ -87,21 +137,41 @@ class LiveRenderer(
             }
             lastPainted = newest
             lastPaintMs = SystemClock.elapsedRealtime()
-            val canvas = holder.lockCanvas()
+            val canvas = lockCanvas(holder)
             if (canvas == null) {
                 // surface not ready (or being resized): do NOT spin on it
                 Thread.sleep(16)
                 continue
             }
+            val t0 = SystemClock.elapsedRealtime()
             try {
                 drawFrame(canvas)
             } finally {
                 holder.unlockCanvasAndPost(canvas)
             }
-            try {
-                Thread.sleep(16)
-            } catch (_: InterruptedException) {
+            val dt = SystemClock.elapsedRealtime() - t0
+            paints++
+            paintMsTotal += dt
+            if (dt > worstPaintMs) worstPaintMs = dt
+            val now = SystemClock.elapsedRealtime()
+            if (now - paintT0 >= 5000) {
+                // The render thread is where stutter is visible; without this the
+                // only signal was dumpsys gfxinfo, which does not see lockCanvas
+                // paints at all (it counted 28 frames while the stream ran at 15 fps).
+                com.mag160c.thermal.media.DebugLog.log(
+                    "render",
+                    "paints=${paints} in ${now - paintT0} ms " +
+                        "avg=%.1f ms worst=$worstPaintMs ms".format(Locale.US, paintMsTotal.toFloat() / paints),
+                )
+                paints = 0
+                paintMsTotal = 0
+                worstPaintMs = 0
+                paintT0 = now
             }
+            // No extra sleep here: the gate at the top of the loop already parks
+            // the thread until a new frame arrives, so sleeping again only added
+            // latency between the camera producing a frame and it reaching the
+            // screen.
         }
     }
 
@@ -129,10 +199,11 @@ class LiveRenderer(
 
         val zoom = vm.state.value.zoom
         val crop = ImageTransform.cropForZoom(zoom)
-        val srcRect = if (zoom > 1) {
+        val src: android.graphics.Rect? = if (zoom > 1) {
             val cw = (320 * (crop[2] - crop[0])).toInt()
             val ch = (240 * (crop[3] - crop[1])).toInt()
-            android.graphics.Rect(160 - cw / 2, 120 - ch / 2, 160 + cw / 2, 120 + ch / 2)
+            srcRect.set(160 - cw / 2, 120 - ch / 2, 160 + cw / 2, 120 + ch / 2)
+            srcRect
         } else null
 
         val size = if (ImageTransform.swapped(params.rotDeg)) {
@@ -142,12 +213,12 @@ class LiveRenderer(
         }
         canvas.save()
         canvas.rotate(params.rotDeg.toFloat(), fit.cx, fit.cy)
-        val dst = android.graphics.RectF(
+        dstRect.set(
             fit.cx - size[0] / 2f, fit.cy - size[1] / 2f,
             fit.cx + size[0] / 2f, fit.cy + size[1] / 2f,
         )
-        if (srcRect != null) canvas.drawBitmap(bitmap, srcRect, dst, paint)
-        else canvas.drawBitmap(bitmap, null, dst, paint)
+        if (src != null) canvas.drawBitmap(bitmap, src, dstRect, paint)
+        else canvas.drawBitmap(bitmap, null, dstRect, paint)
         canvas.restore()
 
         drawOsd(canvas, vm.state.value)
@@ -169,7 +240,6 @@ class LiveRenderer(
             bitmap.setPixels(frame, 0, 320, 0, 0, 320, 240)
             return
         }
-        val flipped = IntArray(320 * 240)
         for (y in 0 until 240) {
             val sy = if (p.flipV) 239 - y else y
             val srcRow = sy * 320
@@ -184,52 +254,51 @@ class LiveRenderer(
     }
 
     /**
-     * One temperature marker. Geometry comes from [AnnotSpec] — the same numbers
-     * the photo, video and analysis markers use — converted from image units to
-     * screen pixels via the displayed image's scale, so a probe looks identical
-     * everywhere.
+     * Draw every marker through the shared [MarkerPainter], the same one that
+     * burns markers into saved photos and video. Using it here (rather than
+     * hand-drawing) is what makes a saved photo look like a screenshot of the live
+     * view — same dot, same ring, same label box, same placement rule.
+     *
+     * The labels are rotated by the grip angle so they stay upright on the rotated
+     * screen; the glyphs are not rotated.
      */
-    private fun drawTempMarker(
-        canvas: Canvas,
-        sx: Int,
-        sy: Int,
-        tempC: Float?,
-        label: String?,
-        tint: Int? = null,
-    ) {
-        if (sx < 0 || sy < 0 || tempC == null) return
-        val p = vm.probeToScreen(sx, sy)
-        val cx = p[0]
-        val cy = p[1]
-        // viewport width / 320 = how many screen px one AnnotSpec unit spans
-        val k = viewport.width() / AnnotSpec.REF_W
-        markerPaint.color = tint ?: Color.WHITE
-        markerPaint.style = Paint.Style.FILL
-        canvas.drawCircle(cx, cy, AnnotSpec.DOT_R * k, markerPaint)
-        markerPaint.style = Paint.Style.STROKE
-        markerPaint.strokeWidth = AnnotSpec.RING_W * k
-        canvas.drawCircle(cx, cy, AnnotSpec.RING_R * k, markerPaint)
-        markerPaint.style = Paint.Style.FILL
-        markerPaint.color = Color.WHITE
-
-        val text = (label?.let { "$it " } ?: "") + "%.1f℃".format(tempC)
-        val half = gripTextHalf(text)
-        val gap = AnnotSpec.labelOffsetX(k)
-        // place the label beside the marker in the TEXT's own frame, so with a
-        // 90 deg grip the label still sits clear of the dot instead of drifting
-        val candidates = floatArrayOf(gap, -gap)
-        var best: FloatArray? = null
-        for (off in candidates) {
-            val c = offsetInTextFrame(cx, cy, off, 0f)
-            val fits = c[0] - half[0] - 2f * k >= viewport.left &&
-                c[0] + half[0] + 2f * k <= viewport.right &&
-                c[1] - half[1] >= viewport.top &&
-                c[1] + half[1] <= viewport.bottom
-            if (fits) { best = c; break }
-            if (best == null) best = c
+    private fun drawMarkers(canvas: Canvas, state: LiveViewModel.LiveState) {
+        marks.clear()
+        for (p in state.probes) {
+            val t = p.tempC ?: continue
+            val scr = vm.probeToScreen(p.x, p.y)
+            marks.add(
+                com.mag160c.thermal.media.MarkerPainter.Mark(
+                    scr[0], scr[1], p.label, t,
+                ),
+            )
         }
-        val c = best!!
-        drawGripText(canvas, text, c[0], c[1])
+        if (state.traceMode.showsMax && state.maxPos >= 0 && state.maxTempC != null) {
+            val scr = vm.probeToScreen(state.maxPos % 160, state.maxPos / 160)
+            marks.add(
+                com.mag160c.thermal.media.MarkerPainter.Mark(
+                    scr[0], scr[1], "max", state.maxTempC, AnnotSpec.EXTREME_TINT,
+                ),
+            )
+        }
+        if (state.traceMode.showsMin && state.minPos >= 0 && state.minTempC != null) {
+            val scr = vm.probeToScreen(state.minPos % 160, state.minPos / 160)
+            marks.add(
+                com.mag160c.thermal.media.MarkerPainter.Mark(
+                    scr[0], scr[1], "min", state.minTempC, AnnotSpec.EXTREME_TINT,
+                ),
+            )
+        }
+        if (marks.isEmpty()) return
+        com.mag160c.thermal.media.MarkerPainter.draw(
+            canvas = canvas,
+            marks = marks,
+            imgW = canvas.width.toFloat(),
+            imgH = canvas.height.toFloat(),
+            // viewport width / 320 = screen pixels per AnnotSpec unit
+            imageUnitsToPixels = viewport.width() / AnnotSpec.REF_W,
+            textRotationDeg = textRot,
+        )
     }
 
     /** Rotate a text-local offset into buffer space and add it to an anchor. */
@@ -261,19 +330,27 @@ class LiveRenderer(
 
     private fun drawColorBar(canvas: Canvas, state: LiveViewModel.LiveState) {
         if (state.maxTempC == null || state.minTempC == null) return
-        val pal = com.mag160c.thermal.core.Palettes.buildAll()[state.paletteIndex]
         val barW = 20f * density
         val barH = viewport.height() * 0.8f
         val x = viewport.right - barW - 12f * density
         val y0 = viewport.top + (viewport.height() - barH) / 2f
-        val seg = Paint()
-        val n = 96
-        for (i in 0 until n) {
-            val c = pal[255 - i * 255 / (n - 1)]
-            seg.color = c
-            val sy = y0 + barH * i / n
-            val ey = y0 + barH * (i + 1) / n
-            canvas.drawRect(x, sy, x + barW, ey + 0.5f, seg)
+        // The strip is a 1x96 bitmap stretched to the bar rect, rebuilt only when
+        // the palette changes. Drawing 96 rects every frame was pure overhead on
+        // the render thread.
+        if (barPaletteIdx != state.paletteIndex || barBitmap == null) {
+            val pal = com.mag160c.thermal.core.Palettes.buildAll()[state.paletteIndex]
+            val bmp = Bitmap.createBitmap(1, BAR_SEGMENTS, Bitmap.Config.ARGB_8888)
+            val px = IntArray(BAR_SEGMENTS)
+            for (i in 0 until BAR_SEGMENTS) {
+                px[i] = pal[255 - i * 255 / (BAR_SEGMENTS - 1)]
+            }
+            bmp.setPixels(px, 0, 1, 0, 0, 1, BAR_SEGMENTS)
+            barBitmap = bmp
+            barPaletteIdx = state.paletteIndex
+        }
+        barBitmap?.let {
+            srcRect.set(0, 0, 1, BAR_SEGMENTS)
+            canvas.drawBitmap(it, srcRect, android.graphics.RectF(x, y0, x + barW, y0 + barH), paint)
         }
         textPaint.color = Color.WHITE
         val maxT = "%.1f".format(state.maxTempC)
@@ -301,23 +378,9 @@ class LiveRenderer(
             val cy = (oy - textPaint.textSize / 2f).coerceAtLeast(viewport.top + half[1] + 4f * density)
             drawGripText(canvas, text, cx, cy)
         }
-        // the trace setting chooses which extremes to mark (max / min / both);
-        // tinted via AnnotSpec so they read the same as in the saved photo
-        if (state.traceMode.showsMax) {
-            drawTempMarker(
-                canvas, state.maxPos % 160, state.maxPos / 160, state.maxTempC, "高",
-                AnnotSpec.EXTREME_TINT,
-            )
-        }
-        if (state.traceMode.showsMin) {
-            drawTempMarker(
-                canvas, state.minPos % 160, state.minPos / 160, state.minTempC, "低",
-                AnnotSpec.EXTREME_TINT,
-            )
-        }
-        for (p in state.probes) {
-            drawTempMarker(canvas, p.x, p.y, p.tempC, p.label)
-        }
+        // probes and the max/min extremes, all through the shared painter so the
+        // saved photo matches this screen exactly
+        drawMarkers(canvas, state)
         drawColorBar(canvas, state)
     }
 }

android/app/src/main/kotlin/com/mag160c/thermal/ui/live/LiveScreen.kt

@@ -95,16 +95,17 @@ fun LiveScreen(vm: LiveViewModel = viewModel(), onOpenGallery: () -> Unit = {})
     LaunchedEffect(Unit) {
         vm.connect()
         vm.uiBottomPx = navPx + shutterPx
-        // Seed the renderer with the persisted orientation settings once; from
-        // then on AppSettings publishes changes, so the settings tab applies
-        // immediately instead of being picked up by this loop (which only runs
-        // while the live tab is composed).
+        // Seed the renderer with the persisted settings once; from then on
+        // AppSettings publishes changes, so the settings tab applies immediately.
         com.mag160c.thermal.ui.settings.ImageOrientationSettings.publishFrom(context)
+        // Temperature/OSD updates run on a background dispatcher inside the view
+        // model: doing that work here (main thread) every 400 ms was the visible
+        // stutter on the device (7.3% janky frames, 60-700 ms tail).
+        vm.startTemperatureLoop()
         while (true) {
             kotlinx.coroutines.delay(400)
             navPx = UiInsets.navPx
             vm.uiBottomPx = navPx + shutterPx
-            vm.refreshTemps()
         }
     }
     // Apply orientation / palette / trace-mode changes the moment they happen
@@ -116,6 +117,7 @@ fun LiveScreen(vm: LiveViewModel = viewModel(), onOpenGallery: () -> Unit = {})
         vm.flipH = settings.flipH
         vm.flipV = settings.flipV
         vm.setTraceMode(settings.traceMode)
+        vm.applyEnhanceLevel(settings.enhanceLevel)
         // palette: only re-apply when the user picks a different default, so a
         // temporary change from the live control bar is not stomped every frame
         if (vm.state.value.paletteIndex != settings.paletteIndex) {

android/app/src/main/kotlin/com/mag160c/thermal/ui/live/LiveViewModel.kt

@@ -53,6 +53,16 @@ class LiveViewModel(app: Application) : AndroidViewModel(app) {
         }
     }
 
+    /** Detail enhancement level 0..4 (vendor strength = level shl 3). */
+    @Volatile
+    var enhanceLevel: Int = 0
+
+    /** Apply the enhancement level to the running pipeline. */
+    fun applyEnhanceLevel(level: Int) {
+        enhanceLevel = level.coerceIn(0, 4)
+        session.setEnhanceStrength(enhanceLevel shl 3)
+    }
+
     /** Which extremes the trace markers display (settings choice). */
     enum class TraceMode {
         MAX, MIN, BOTH, NONE;
@@ -145,15 +155,11 @@ class LiveViewModel(app: Application) : AndroidViewModel(app) {
                     com.mag160c.thermal.media.DebugLog.log(
                         "vm", "next connect in ${delayMs} ms (failures=$connectFailures)",
                     )
-                    // Exactly one retry may be pending at a time. Retrying is what
-                    // recovers a camera that rebooted itself; without it the UI sat
-                    // on "no_handshake" forever after a single failure.
-                    if (retryJob?.isActive != true) {
-                        retryJob = viewModelScope.launch {
-                            kotlinx.coroutines.delay(delayMs)
-                            if (!session.isStreaming()) connect()
-                        }
-                    }
+                    // Exactly one retry is pending at any time; the newest delay
+                    // replaces an older one. Retrying is what recovers a camera that
+                    // rebooted itself; without it the UI sat on "no_handshake"
+                    // forever after a single failure.
+                    scheduleRetry(delayMs)
                 }
                 IrSession.State.IDLE -> {
                     connectInFlightUi = false
@@ -337,6 +343,24 @@ class LiveViewModel(app: Application) : AndroidViewModel(app) {
      */
     private var retryJob: kotlinx.coroutines.Job? = null
 
+    /**
+     * Queue the one pending reconnect. The newest request always wins (an ERROR
+     * backoff replaces an earlier short retry), so [retryJob] is a single slot
+     * rather than a growing set of timers. The previous job is cancelled AFTER the
+     * replacement is created, because this can be called from inside a running
+     * retry's own connect() — cancelling first would kill the caller before the new
+     * timer exists, which is exactly the dead end this replaces.
+     */
+    private fun scheduleRetry(delayMs: Long) {
+        val previous = retryJob
+        val job = viewModelScope.launch {
+            kotlinx.coroutines.delay(delayMs)
+            if (!session.isStreaming()) connect()
+        }
+        retryJob = job
+        previous?.cancel()
+    }
+
     /**
      * Serialises connect attempts for the whole process.
      *
@@ -381,15 +405,27 @@ class LiveViewModel(app: Application) : AndroidViewModel(app) {
     fun connect() {
         val now = android.os.SystemClock.elapsedRealtime()
         if (now - lastConnectMs < 800) {
-            com.mag160c.thermal.media.DebugLog.log("vm", "connect() debounced")
+            // Defer, never drop. Dropping was a real dead end on the device: the
+            // camera re-enumerates right after the app starts (the previous owner
+            // of the interface died), so the FIRST connect finds no device and
+            // reports no_device, and the ATTACHED broadcast that lands 200 ms later
+            // fell inside this window and was thrown away — the app then sat on
+            // "no camera" until it was restarted by hand.
+            val remaining = 800 - (now - lastConnectMs)
+            com.mag160c.thermal.media.DebugLog.log("vm", "connect() debounced, retry in ${remaining} ms")
+            if (!session.isStreaming()) scheduleRetry(remaining + 50)
             return
         }
         if (now < nextConnectAllowedMs) {
+            val wait = nextConnectAllowedMs - now
             com.mag160c.thermal.media.DebugLog.log(
                 "vm",
-                "connect() backed off for ${(nextConnectAllowedMs - now)} ms " +
-                    "(failures=$connectFailures)",
+                "connect() backed off for ${wait} ms (failures=$connectFailures)",
             )
+            // Same reasoning as the debounce above: a request that arrives inside
+            // the backoff window is pending work, not noise, so it is rescheduled
+            // instead of discarded. A success resets the backoff (see the listener).
+            if (!session.isStreaming()) scheduleRetry(wait + 50)
             return
         }
         lastConnectMs = now
@@ -443,6 +479,13 @@ class LiveViewModel(app: Application) : AndroidViewModel(app) {
                     status = "no_device",
                 )
                 releaseConnectLock(generation)
+                // A missing device is usually transient: the camera is mid
+                // re-enumeration (it drops off the bus for ~1 s when the previous
+                // holder releases the interface, and again right after a handshake
+                // failure). Without a retry the app stayed on "no camera" forever;
+                // the ATTACHED broadcast is not a reliable second chance because it
+                // can arrive inside the connect debounce window.
+                scheduleRetry(1500)
                 return
             }
             transport.requestPermission { ok ->
@@ -541,14 +584,43 @@ class LiveViewModel(app: Application) : AndroidViewModel(app) {
     }
 
     /** Current probes as markers, for burning into photos and video frames. */
-    private fun probesAsMarks(): List<com.mag160c.thermal.media.MarkerPainter.Mark> =
-        _state.value.probes.mapNotNull { p ->
-            p.tempC?.let {
+    /**
+     * Every marker the live screen is showing, in SENSOR coordinates (the space the
+     * recorded 320x240 frame uses): the user's probes plus the traced extremes when
+     * the trace setting asks for them. A recording therefore carries the same
+     * readouts as the screen it was made from.
+     */
+    private fun probesAsMarks(): List<com.mag160c.thermal.media.MarkerPainter.Mark> {
+        val st = _state.value
+        val out = ArrayList<com.mag160c.thermal.media.MarkerPainter.Mark>(
+            st.probes.size + 2,
+        )
+        for (p in st.probes) {
+            val t = p.tempC ?: continue
+            out.add(
                 com.mag160c.thermal.media.MarkerPainter.Mark(
-                    p.x.toFloat(), p.y.toFloat(), p.label, it,
-                )
-            }
+                    p.x.toFloat(), p.y.toFloat(), p.label, t,
+                ),
+            )
         }
+        if (st.traceMode.showsMax && st.maxPos >= 0 && st.maxTempC != null) {
+            out.add(
+                com.mag160c.thermal.media.MarkerPainter.Mark(
+                    (st.maxPos % 160).toFloat(), (st.maxPos / 160).toFloat(),
+                    "max", st.maxTempC, com.mag160c.thermal.core.AnnotSpec.EXTREME_TINT,
+                ),
+            )
+        }
+        if (st.traceMode.showsMin && st.minPos >= 0 && st.minTempC != null) {
+            out.add(
+                com.mag160c.thermal.media.MarkerPainter.Mark(
+                    (st.minPos % 160).toFloat(), (st.minPos / 160).toFloat(),
+                    "min", st.minTempC, com.mag160c.thermal.core.AnnotSpec.EXTREME_TINT,
+                ),
+            )
+        }
+        return out
+    }
 
     /**
      * Capture: rendered JPEG + NUC data + probes -> MDT -> MediaStore.
@@ -584,7 +656,7 @@ class LiveViewModel(app: Application) : AndroidViewModel(app) {
             extremes.add(
                 com.mag160c.thermal.media.MarkerPainter.Mark(
                     (st.maxPos % 160).toFloat(), (st.maxPos / 160).toFloat(),
-                    "高", st.maxTempC, com.mag160c.thermal.core.AnnotSpec.EXTREME_TINT,
+                    "max", st.maxTempC, com.mag160c.thermal.core.AnnotSpec.EXTREME_TINT,
                 ),
             )
         }
@@ -592,7 +664,7 @@ class LiveViewModel(app: Application) : AndroidViewModel(app) {
             extremes.add(
                 com.mag160c.thermal.media.MarkerPainter.Mark(
                     (st.minPos % 160).toFloat(), (st.minPos / 160).toFloat(),
-                    "低", st.minTempC, com.mag160c.thermal.core.AnnotSpec.EXTREME_TINT,
+                    "min", st.minTempC, com.mag160c.thermal.core.AnnotSpec.EXTREME_TINT,
                 ),
             )
         }
@@ -629,6 +701,20 @@ class LiveViewModel(app: Application) : AndroidViewModel(app) {
             nucPixels = if (haveNuc) {
                 com.mag160c.thermal.media.PhotoSaver.packNucForPhoto(nuc160)
             } else null,
+            renderParams = com.mag160c.thermal.media.Mdt.encodeRenderParams(
+                com.mag160c.thermal.media.Mdt.RenderParams(mirror.flipH, mirror.flipV),
+            ),
+            // The extremes are recorded as the capture saw them, so the analysis
+            // screen draws the SAME marker as the one burned into the JPEG instead
+            // of re-deriving a slightly different one from the NUC block.
+            extremes = com.mag160c.thermal.media.Mdt.encodeExtremes(
+                com.mag160c.thermal.media.Mdt.Extremes(
+                    minPos = if (tm.showsMin) st.minPos else -1,
+                    maxPos = if (tm.showsMax) st.maxPos else -1,
+                    minMc = if (tm.showsMin && st.minTempC != null) (st.minTempC * 1000f).toInt() else 0,
+                    maxMc = if (tm.showsMax && st.maxTempC != null) (st.maxTempC * 1000f).toInt() else 0,
+                ),
+            ),
         )
         val saved = com.mag160c.thermal.media.PhotoSaver.saveMdt(
             context, mdt, com.mag160c.thermal.media.PhotoSaver.fileName(),
@@ -765,8 +851,42 @@ class LiveViewModel(app: Application) : AndroidViewModel(app) {
         }
     }
 
-    /** Update per-frame temperature stats (called on a slow timer). */
-    fun refreshTemps() {
+    /** Reusable scratch for the NUC snapshot (avoids a 19200-int alloc per tick). */
+    private val nucScratch = IntArray(19200)
+
+    /** True while the background temperature loop runs. */
+    private val tempLoopStarted = java.util.concurrent.atomic.AtomicBoolean(false)
+
+    /**
+     * Start the temperature/OSD update loop.
+     *
+     * It runs on [Dispatchers.Default] and only touches Compose state at the end:
+     * the previous version did the whole job on the MAIN thread (it was driven by a
+     * LaunchedEffect), which meant a 19200-element allocation, a full pixel scan and
+     * `copyNuc` — that call takes the pipeline lock the reader thread is holding —
+     * every 400 ms. On the device that showed up as 7.3% janky frames with a tail of
+     * 60-700 ms frames: the visible stutter.
+     */
+    fun startTemperatureLoop() {
+        if (!tempLoopStarted.compareAndSet(false, true)) return
+        viewModelScope.launch(Dispatchers.Default) {
+            while (true) {
+                kotlinx.coroutines.delay(400)
+                try {
+                    computeAndPublishTemps()
+                } catch (e: Exception) {
+                    com.mag160c.thermal.media.DebugLog.log("vm", "temp loop error: $e")
+                }
+            }
+        }
+    }
+
+    /**
+     * Heavy part of the temperature update, safe to call from a background thread:
+     * reads the pipeline once, scans the counts, then publishes the result to the UI
+     * state on the main dispatcher.
+     */
+    private suspend fun computeAndPublishTemps() {
         if (uiTick++ % 12 == 0) {
             // ~5 s heartbeat: what the UI currently sees (debug round 11)
             com.mag160c.thermal.media.DebugLog.log(
@@ -781,49 +901,55 @@ class LiveViewModel(app: Application) : AndroidViewModel(app) {
         // mid-update. Skip rather than show nonsense.
         if (!session.tempsReady()) return
         val centerMc = session.probeTemp(80, 60)
-        val nuc = IntArray(19200)
-        if (!session.copyNuc(nuc)) return
-        updateTemps(centerMc, nuc)
-    }
+        if (!session.copyNuc(nucScratch)) return
 
-    private var uiTick = 0
-
-    /**
-     * @param centerMc centre temperature in MILLIDEGREES C, as returned by
-     *   [IrSession.probeTemp] — it must NOT be converted again here (the old
-     *   code ran countsToTempMc() on an already-converted value, which showed
-     *   e.g. 108.7 C for a ~24 C scene).
-     * @param nuc raw NUC counts, converted here once.
-     */
-    private fun updateTemps(centerMc: Int?, nuc: IntArray) {
+        // scan off the main thread: 19200 iterations plus probe conversions
         var mn = Int.MAX_VALUE
         var mx = -1
         var mnPos = -1
         var mxPos = -1
-        for (i in nuc.indices) {
-            val v = nuc[i]
-            if (v < mn) {
-                mn = v
-                mnPos = i
-            }
-            if (v > mx) {
-                mx = v
-                mxPos = i
+        for (i in nucScratch.indices) {
+            val v = nucScratch[i]
+            if (v < mn) { mn = v; mnPos = i }
+            if (v > mx) { mx = v; mxPos = i }
+        }
+        val probeTemps = _state.value.probes.map { p ->
+            (p.x + p.y * 160).let { idx ->
+                if (idx in nucScratch.indices) TempMath.countsToTempMc(nucScratch[idx]) / 1000f
+                else 0f
             }
         }
-        val probes = _state.value.probes.map { p ->
-            p.copy(tempC = TempMath.countsToTempMc(nuc[p.y * 160 + p.x]) / 1000f)
+        val minT = if (mn != Int.MAX_VALUE) TempMath.countsToTempMc(mn) / 1000f else null
+        val maxT = if (mx >= 0) TempMath.countsToTempMc(mx) / 1000f else null
+        val centerT = centerMc?.let { it / 1000f }
+
+        withContext(Dispatchers.Main) {
+            val probes = _state.value.probes.mapIndexed { i, p ->
+                p.copy(tempC = probeTemps.getOrElse(i) { p.tempC ?: 0f })
+            }
+            _state.value = _state.value.copy(
+                centerTempC = centerT,
+                maxTempC = maxT,
+                minTempC = minT,
+                maxPos = mxPos,
+                minPos = mnPos,
+                probes = probes,
+            )
         }
-        _state.value = _state.value.copy(
-            centerTempC = centerMc?.let { it / 1000f },
-            maxTempC = if (mx >= 0) TempMath.countsToTempMc(mx) / 1000f else null,
-            minTempC = if (mn <= Int.MAX_VALUE) TempMath.countsToTempMc(mn) / 1000f else null,
-            maxPos = mxPos,
-            minPos = mnPos,
-            probes = probes,
-        )
     }
 
+    /** One-shot temperature refresh (kept for callers that need it immediately). */
+    fun refreshTemps() {
+        viewModelScope.launch(Dispatchers.Default) {
+            try {
+                computeAndPublishTemps()
+            } catch (_: Exception) {
+            }
+        }
+    }
+
+    private var uiTick = 0
+
     override fun onCleared() {
         remoteHost.stop()
         session.destroy()

android/app/src/main/kotlin/com/mag160c/thermal/ui/settings/AppSettings.kt

@@ -23,6 +23,8 @@ object ImageOrientationSettings {
         val paletteIndex: Int = 2,
         val traceMode: com.mag160c.thermal.ui.live.LiveViewModel.TraceMode =
             com.mag160c.thermal.ui.live.LiveViewModel.TraceMode.BOTH,
+        /** Detail enhancement level 0..4 (see AppSettings.enhanceLevel). */
+        val enhanceLevel: Int = 0,
     )
 
     private val _state = MutableStateFlow(State())
@@ -34,8 +36,9 @@ object ImageOrientationSettings {
         flipV: Boolean,
         paletteIndex: Int = _state.value.paletteIndex,
         traceMode: com.mag160c.thermal.ui.live.LiveViewModel.TraceMode = _state.value.traceMode,
+        enhanceLevel: Int = _state.value.enhanceLevel,
     ) {
-        _state.value = State(rotateDeg, flipH, flipV, paletteIndex, traceMode)
+        _state.value = State(rotateDeg, flipH, flipV, paletteIndex, traceMode, enhanceLevel)
     }
 
     /** Read persisted values and publish them (called when settings load). */
@@ -43,7 +46,7 @@ object ImageOrientationSettings {
         val s = AppSettings(context)
         publish(
             s.imageRotateDeg, s.imageFlipH, s.imageFlipV,
-            s.defaultPaletteIndex, s.traceMode,
+            s.defaultPaletteIndex, s.traceMode, s.enhanceLevel,
         )
     }
 }
@@ -72,6 +75,24 @@ class AppSettings(context: Context) {
             )
         }
 
+    /**
+     * Local 7x7 detail enhancement strength (vendor FilterDetailEnhancement).
+     * 0 = off; the vendor uses `level shl 3` for levels 0..4.
+     *
+     * Defaults to OFF because the port has no official reference output to verify
+     * against (the byte-exact baseline predates this stage) — see DetailEnhance.
+     * Exposed as the "图像增强" setting so the effect can be compared on a device.
+     */
+    var enhanceLevel: Int
+        get() = sp.getInt("enhanceLevel", 0)
+        set(v) {
+            val n = v.coerceIn(0, 4)
+            sp.edit().putInt("enhanceLevel", n).apply()
+            ImageOrientationSettings.publish(
+                imageRotateDeg, imageFlipH, imageFlipV, enhanceLevel = n,
+            )
+        }
+
     var defaultEmissivityPercent: Int
         get() = sp.getInt("emissivity", 100)
         set(v) = sp.edit().putInt("emissivity", v).apply()
@@ -129,7 +150,7 @@ class AppSettings(context: Context) {
         // seed the observable with the persisted settings, so a fresh process
         // starts with what the user chose (not the hard-coded defaults)
         ImageOrientationSettings.publish(
-            imageRotateDeg, imageFlipH, imageFlipV, defaultPaletteIndex, traceMode,
+            imageRotateDeg, imageFlipH, imageFlipV, defaultPaletteIndex, traceMode, enhanceLevel,
         )
     }
 }

android/app/src/main/kotlin/com/mag160c/thermal/ui/settings/SettingsScreen.kt

@@ -45,6 +45,8 @@ fun SettingsScreen(
     var language by remember { mutableStateOf(settings.language) }
     // trace mode (max / min / both / off)
     var traceMode by remember { mutableStateOf(settings.traceMode) }
+    // detail enhancement level 0..4 (0 = off)
+    var enhanceLevel by remember { mutableStateOf(settings.enhanceLevel) }
     // remote-preview server toggle (Phase F); off by default, needs live USB
     var remoteOn by remember { mutableStateOf(remoteHostRunning) }
     var showNeedDevice by remember { mutableStateOf(false) }
@@ -78,6 +80,9 @@ fun SettingsScreen(
         ) { dialog = "language" }
         // manual orientation corrections (the official app has the same three)
         SettingRow("旋转USB画面", "$rotateDeg°") { dialog = "rotate" }
+        SettingRow("图像增强", if (enhanceLevel == 0) "关闭" else "${enhanceLevel} 级") {
+            dialog = "enhance"
+        }
         SettingRow("水平翻转", if (flipH) "已开启" else "已关闭") {
             flipH = !flipH
             settings.imageFlipH = flipH
@@ -235,6 +240,37 @@ fun SettingsScreen(
             },
             confirmButton = {},
         )
+        "enhance" -> AlertDialog(
+            onDismissRequest = { dialog = null },
+            title = { Text("图像增强") },
+            text = {
+                Column {
+                    Text(
+                        "加强局部细节（官方同款 7×7 局部映射）。等级越高细节越明显，" +
+                            "噪声也会更明显。",
+                        style = MaterialTheme.typography.bodySmall,
+                        color = MaterialTheme.colorScheme.onSurfaceVariant,
+                        modifier = Modifier.padding(bottom = 8.dp),
+                    )
+                    listOf(0 to "关闭", 1 to "1 级", 2 to "2 级", 3 to "3 级", 4 to "4 级")
+                        .forEach { (lvl, label) ->
+                            Text(
+                                label,
+                                color = if (lvl == enhanceLevel) MaterialTheme.colorScheme.primary
+                                else MaterialTheme.colorScheme.onSurface,
+                                modifier = Modifier
+                                    .clickable {
+                                        enhanceLevel = lvl
+                                        settings.enhanceLevel = lvl
+                                        dialog = null
+                                    }
+                                    .padding(12.dp),
+                            )
+                        }
+                }
+            },
+            confirmButton = {},
+        )
         "trace" -> AlertDialog(
             onDismissRequest = { dialog = null },
             title = { Text("追踪标记") },

android/app/src/main/kotlin/com/mag160c/thermal/usb/IrSession.kt

@@ -126,6 +126,14 @@ class IrSession(context: Context) {
     var lastInfo1: ByteArray? = null
         private set
 
+    /**
+     * Detail enhancement strength requested before a pipeline existed (the
+     * pipeline is built during connect, so a setting change made while
+     * disconnected would otherwise be lost).
+     */
+    @Volatile
+    private var pendingEnhanceStrength: Int = 0
+
     /** Device power-on lifetime in ms (official getDevLifeTime); -1 = unknown. */
     @Volatile
     var deviceLifetimeMs: Long = -1
@@ -293,6 +301,9 @@ class IrSession(context: Context) {
                     epOut, epResp, "FFC($param)",
                 )
             },
+            // the user's detail-enhancement choice must survive a reconnect, so it
+            // is applied at construction rather than only when the setting changes
+            enhanceStrength = pendingEnhanceStrength,
         )
         if (!pipe.loadDdt(ddt)) {
             DebugLog.log("session", "ddt_fail (fetched/bundled ${ddt.size} B not loadable)")
@@ -689,6 +700,12 @@ class IrSession(context: Context) {
         pipeline?.setPalette(index)
     }
 
+    /** Detail enhancement strength (0 = off); applied to the live pipeline. */
+    fun setEnhanceStrength(strength: Int) {
+        pendingEnhanceStrength = strength
+        pipeline?.setEnhanceStrength(strength)
+    }
+
     /** Slow-path probe: temperature at a sensor pixel in millidegrees C. */
     fun probeTemp(x: Int, y: Int): Int? = pipeline?.probeTemp(x, y)
 

android/app/src/test/kotlin/com/mag160c/thermal/core/AnnotSpecPlaceLabelTest.kt

@@ -0,0 +1,116 @@
+package com.mag160c.thermal.core
+
+import org.junit.Assert.assertEquals
+import org.junit.Assert.assertTrue
+import org.junit.Test
+
+/**
+ * Label placement is what keeps a marker readable: the box must stay inside the
+ * image and must not cover a label that is already there. Both failures were
+ * observed on a real photo — "max" printed straight through "min" — so they are
+ * pinned here.
+ */
+class AnnotSpecPlaceLabelTest {
+
+    private val scale = 1f
+    private fun boxW() = 60f
+    private fun boxH() = 14f
+
+    @Test
+    fun labelSitsRightOfTheMarkerWhenThereIsRoom() {
+        val pos = AnnotSpec.placeLabel(
+            cx = 100f, cy = 100f, boxW = boxW(), boxH = boxH(),
+            imgW = 320f, imgH = 240f, scale = scale,
+        )
+        assertEquals(100f + AnnotSpec.labelOffsetX(scale), pos[0], 0.01f)
+        assertEquals(100f - boxH() / 2f, pos[1], 0.01f)
+    }
+
+    @Test
+    fun labelFlipsLeftInsteadOfOverflowingTheRightEdge() {
+        val pos = AnnotSpec.placeLabel(
+            cx = 310f, cy = 100f, boxW = boxW(), boxH = boxH(),
+            imgW = 320f, imgH = 240f, scale = scale,
+        )
+        assertTrue("must stay inside the image, was ${pos[0]}", pos[0] + boxW() <= 320f)
+        assertTrue("must stay on the left of its marker", pos[0] < 310f)
+    }
+
+    @Test
+    fun labelStaysInsideTheImageWhenTheMarkerIsAtTheCorner() {
+        val pos = AnnotSpec.placeLabel(
+            cx = 1f, cy = 1f, boxW = boxW(), boxH = boxH(),
+            imgW = 320f, imgH = 240f, scale = scale,
+        )
+        assertTrue("x=${pos[0]}", pos[0] >= 0f)
+        assertTrue("y=${pos[1]}", pos[1] >= 0f)
+    }
+
+    @Test
+    fun secondLabelIsMovedClearOfTheFirst() {
+        val first = AnnotSpec.placeLabel(
+            cx = 100f, cy = 100f, boxW = boxW(), boxH = boxH(),
+            imgW = 320f, imgH = 240f, scale = scale,
+        )
+        val placed = listOf(floatArrayOf(first[0], first[1], boxW(), boxH()))
+        // a marker close enough that the default position would overlap
+        val second = AnnotSpec.placeLabel(
+            cx = 105f, cy = 104f, boxW = boxW(), boxH = boxH(),
+            imgW = 320f, imgH = 240f, scale = scale, placed = placed,
+        )
+        val overlaps = second[0] < first[0] + boxW() && second[0] + boxW() > first[0] &&
+            second[1] < first[1] + boxH() && second[1] + boxH() > first[1]
+        assertTrue(
+            "second label at (${second[0]},${second[1]}) still overlaps " +
+                "(${first[0]},${first[1]})",
+            !overlaps,
+        )
+    }
+
+    @Test
+    fun secondLabelFitsEntirelyInsideTheImageAfterAvoiding() {
+        val first = AnnotSpec.placeLabel(
+            cx = 100f, cy = 100f, boxW = boxW(), boxH = boxH(),
+            imgW = 320f, imgH = 240f, scale = scale,
+        )
+        val placed = listOf(floatArrayOf(first[0], first[1], boxW(), boxH()))
+        val second = AnnotSpec.placeLabel(
+            cx = 104f, cy = 102f, boxW = boxW(), boxH = boxH(),
+            imgW = 320f, imgH = 240f, scale = scale, placed = placed,
+        )
+        assertTrue("x=${second[0]}", second[0] >= 0f)
+        assertTrue("x+w=${second[0] + boxW()}", second[0] + boxW() <= 320f)
+        assertTrue("y=${second[1]}", second[1] >= 0f)
+        assertTrue("y+h=${second[1] + boxH()}", second[1] + boxH() <= 240f)
+    }
+
+    @Test
+    fun aCrowdOfLabelsAllStayInsideTheImage() {
+        // Worst case from the device: the extremes cluster in one corner and the
+        // probes pile up around them.
+        val placed = ArrayList<FloatArray>()
+        for (i in 0 until 8) {
+            val pos = AnnotSpec.placeLabel(
+                cx = 10f + i * 2f, cy = 10f + i * 2f,
+                boxW = boxW(), boxH = boxH(),
+                imgW = 320f, imgH = 240f, scale = scale, placed = placed,
+            )
+            placed.add(floatArrayOf(pos[0], pos[1], boxW(), boxH()))
+        }
+        for (b in placed) {
+            assertTrue("x=${b[0]}", b[0] >= 0f)
+            assertTrue("x+w=${b[0] + b[2]}", b[0] + b[2] <= 320f + 0.01f)
+            assertTrue("y=${b[1]}", b[1] >= 0f)
+            assertTrue("y+h=${b[1] + b[3]}", b[1] + b[3] <= 240f + 0.01f)
+        }
+    }
+
+    @Test
+    fun scaleKeepsTheOffsetProportional() {
+        val small = AnnotSpec.placeLabel(100f, 100f, 60f, 14f, 320f, 240f, 1f)
+        val large = AnnotSpec.placeLabel(300f, 300f, 180f, 42f, 960f, 720f, 3f)
+        // the gap from the marker to the box grows with the scale factor
+        assertEquals(AnnotSpec.labelOffsetX(3f), large[0] - 300f, 0.01f)
+        assertEquals(AnnotSpec.labelOffsetX(1f), small[0] - 100f, 0.01f)
+    }
+}

android/app/src/test/kotlin/com/mag160c/thermal/core/DetailEnhanceTest.kt

@@ -0,0 +1,130 @@
+package com.mag160c.thermal.core
+
+import org.junit.Assert.assertArrayEquals
+import org.junit.Assert.assertEquals
+import org.junit.Assert.assertTrue
+import org.junit.Test
+
+/**
+ * Port of the vendor's 7x7 local detail enhancement
+ * (`CFunctions::FilterDetailEnhancement_Simple` + `LocalMap7x7_Simple`).
+ *
+ * What can and cannot be asserted here: there is no official output to diff
+ * against (the byte-exact baseline predates this stage), so these tests pin the
+ * CONTRACT — off is a true no-op, the filter stays inside the 8-bit range, it
+ * amplifies local contrast rather than shifting the overall level, and it never
+ * touches the border the vendor leaves alone.
+ */
+class DetailEnhanceTest {
+    private val w = 160
+    private val h = 120
+
+    private fun flat(value: Int): IntArray = IntArray(w * h) { value }
+
+    /** A smooth ramp: no local contrast, so nothing should be enhanced. */
+    private fun ramp(): IntArray = IntArray(w * h) { i -> 7000 + (i % w) }
+
+    /** A checkerboard: maximum local contrast everywhere. */
+    private fun checkerboard(lo: Int, hi: Int): IntArray =
+        IntArray(w * h) { i -> if (((i % w) / 4 + (i / w) / 4) % 2 == 0) lo else hi }
+
+    private fun grayOf(v: Int): ByteArray = ByteArray(w * h) { v.toByte() }
+
+    @Test
+    fun zeroStrengthIsANoOp() {
+        // the default must leave the verified reference path untouched
+        val gray = grayOf(120)
+        val before = gray.copyOf()
+        val de = DetailEnhance(w, h)
+        de.enhance(ramp(), gray, strength = 0, gain = 3000)
+        assertArrayEquals("strength 0 must not change a single pixel", before, gray)
+    }
+
+    @Test
+    fun flatFieldIsUnchanged() {
+        // a constant frame has zero local range: the vendor's range guard means no
+        // pixel may be touched (this is what keeps uniform scenes from boiling)
+        val gray = grayOf(100)
+        val before = gray.copyOf()
+        DetailEnhance(w, h).enhance(flat(7200), gray, strength = 8, gain = 3000)
+        assertArrayEquals("flat input must stay flat", before, gray)
+    }
+
+    @Test
+    fun localContrastIsAmplified() {
+        // a checkerboard has strong local contrast: the filter must push pixels
+        // away from the local mean, i.e. change something
+        val gray = grayOf(128)
+        val before = gray.copyOf()
+        DetailEnhance(w, h).enhance(checkerboard(6500, 8000), gray, strength = 8, gain = 3000)
+        var changed = 0
+        for (i in gray.indices) if (gray[i] != before[i]) changed++
+        assertTrue("expected contrast to change pixels, changed=$changed", changed > 0)
+    }
+
+    @Test
+    fun outputStaysInsideTheRangeThePaletteAccepts() {
+        // gray values feed a 256-entry palette; anything outside 0..255 would wrap
+        val gray = grayOf(250)
+        DetailEnhance(w, h).enhance(checkerboard(0, 65535), gray, strength = 64, gain = 0xFFFF)
+        for (i in gray.indices) {
+            val v = gray[i].toInt() and 0xFF
+            assertTrue("gray[$i]=$v out of range", v in 0..255)
+        }
+    }
+
+    @Test
+    fun bordersAreLeftAlone() {
+        // the vendor only processes rows/cols 3..(H/W-4); keep that margin so the
+        // image edge does not develop a halo
+        val gray = grayOf(128)
+        val before = gray.copyOf()
+        DetailEnhance(w, h).enhance(checkerboard(6000, 9000), gray, strength = 16, gain = 3000)
+        for (y in 0 until h) {
+            for (x in 0 until w) {
+                if (x < 3 || y < 3 || x >= w - 3 || y >= h - 3) {
+                    assertEquals("border pixel ($x,$y) must be untouched", before[y * w + x], gray[y * w + x])
+                }
+            }
+        }
+    }
+
+    @Test
+    fun strongerStrengthChangesAtLeastAsMuch() {
+        // monotonic in the strength parameter: a plausible-strength sweep must not
+        // do LESS work at a higher setting
+        fun changedAt(s: Int): Int {
+            val gray = grayOf(128)
+            val before = gray.copyOf()
+            DetailEnhance(w, h).enhance(checkerboard(6500, 8000), gray, strength = s, gain = 3000)
+            return gray.indices.count { gray[it] != before[it] }
+        }
+        val weak = changedAt(2)
+        val strong = changedAt(16)
+        assertTrue("strong=$strong should be >= weak=$weak", strong >= weak)
+    }
+
+    @Test
+    fun gainScalesTheEffect() {
+        fun changedAt(g: Int): Int {
+            val gray = grayOf(128)
+            val before = gray.copyOf()
+            DetailEnhance(w, h).enhance(checkerboard(6500, 8000), gray, strength = 8, gain = g)
+            return gray.indices.count { gray[it] != before[it] }
+        }
+        assertTrue("gain 0 is a no-op", changedAt(0) == 0)
+        assertTrue("a real gain must change something", changedAt(3000) > 0)
+    }
+
+    @Test
+    fun doesNotChangeTheOverallLevelOfASmoothImage() {
+        // on a smooth ramp the mean and the centre are equal, so no delta should be
+        // produced: local enhancement must not act as a brightness shift
+        val gray = grayOf(128)
+        val before = gray.copyOf()
+        DetailEnhance(w, h).enhance(ramp(), gray, strength = 32, gain = 3000)
+        var changed = 0
+        for (i in gray.indices) if (gray[i] != before[i]) changed++
+        assertEquals("a smooth ramp must be left alone", 0, changed)
+    }
+}

android/app/src/test/kotlin/com/mag160c/thermal/media/PhotoNucMappingTest.kt

@@ -114,4 +114,80 @@ class PhotoNucMappingTest {
         )
         assertTrue("no NUC block -> no temperature data", !Mdt.parse(mdt)!!.hasTemperatureData)
     }
+
+    /**
+     * The extremes are stored in SENSOR coordinates next to probes that use the
+     * same space, so the photo builder must map them exactly like a probe. On a
+     * real photo they were added raw, which put both "max" and "min" a few dozen
+     * pixels from the origin — in the top-left corner — instead of over the hot
+     * and cold spots they name.
+     */
+    @Test
+    fun extremesUseTheSameSensorMappingAsProbes() {
+        val mirror = PhotoSaver.Mirror(false, true)   // the user's mount correction
+        val probe = PhotoSaver.sensorToPhoto(120, 90, mirror, 960, 720)
+        val extreme = PhotoSaver.sensorToPhoto(120, 90, mirror, 960, 720)
+        assertEquals("an extreme at a probe's pixel lands on the same photo pixel",
+            probe[0], extreme[0], 0.01f)
+        assertEquals(probe[1], extreme[1], 0.01f)
+        // and it is nowhere near the origin: sensor (120,90) is right of centre,
+        // flipped vertically it is above centre
+        assertTrue("x=${extreme[0]} must be well right of the origin", extreme[0] > 480f)
+        assertTrue("y=${extreme[1]} must sit in the upper half after flipV", extreme[1] < 360f)
+    }
+
+    /** A probe and an extreme 3 sensor pixels apart must stay 3 pixels apart. */
+    @Test
+    fun extremesKeepTheirDistanceFromProbesUnderEveryMirror() {
+        for (flipH in booleanArrayOf(false, true)) {
+            for (flipV in booleanArrayOf(false, true)) {
+                val m = PhotoSaver.Mirror(flipH, flipV)
+                val a = PhotoSaver.sensorToPhoto(100, 60, m, 960, 720)
+                val b = PhotoSaver.sensorToPhoto(103, 60, m, 960, 720)
+                assertEquals(
+                    "flipH=$flipV: 3 sensor pixels stay 3 photo pixels",
+                    18f, kotlin.math.abs(a[0] - b[0]), 0.01f,
+                )
+            }
+        }
+    }
+
+    /**
+     * The capture's own extremes travel in the container. The analysis screen used
+     * to re-derive them from the NUC block, which cannot reproduce the live answer
+     * exactly (the sensor drifts), so a photo showed two "min" markers a few pixels
+     * apart — the burned-in one and the freshly computed one.
+     */
+    @Test
+    fun recordedExtremesSurviveTheContainer() {
+        val e = Mdt.Extremes(minPos = 60 * 160 + 12, maxPos = 22 * 160 + 130, minMc = 21_987, maxMc = 32_615)
+        val mdt = Mdt.compose(
+            jpg = byteArrayOf(0xFF.toByte(), 0xD8.toByte(), 0xFF.toByte(), 0xD9.toByte()),
+            info0 = null, info1 = null, framePixels = ByteArray(38400),
+            nucPixels = PhotoSaver.packNucForPhoto(IntArray(160 * 120)),
+            extremes = Mdt.encodeExtremes(e),
+        )
+        val back = Mdt.parse(mdt)!!.extremes
+        assertEquals(e.minPos, back.minPos)
+        assertEquals(e.maxPos, back.maxPos)
+        // millidegrees survive exactly: rounding them to whole degrees would make
+        // the analysis readout differ from the marker burned into the photo
+        assertEquals(e.minMc, back.minMc)
+        assertEquals(e.maxMc, back.maxMc)
+    }
+
+    @Test
+    fun aPhotoWithoutExtremesReportsNone() {
+        val mdt = Mdt.compose(
+            jpg = byteArrayOf(0xFF.toByte(), 0xD8.toByte(), 0xFF.toByte(), 0xD9.toByte()),
+            info0 = null, info1 = null, framePixels = ByteArray(38400),
+        )
+        val back = Mdt.parse(mdt)!!.extremes
+        assertEquals(-1, back.minPos)
+        assertEquals(-1, back.maxPos)
+        assertTrue("nothing traced -> nothing to prefer", !Mdt.Extremes.hasAny(back))
+        // and the parse of a malformed block must not throw or invent data
+        assertTrue(!Mdt.Extremes.hasAny(Mdt.parseExtremes("garbage".toByteArray())))
+        assertTrue(!Mdt.Extremes.hasAny(Mdt.parseExtremes(null)))
+    }
 }

docs/android_app/session_state.md

@@ -489,6 +489,105 @@
       "未连接"分支显示，正常出图时用户看不到任何反馈）。
 - [x] 单测 66 → **76 项全绿**；debug + release(R8) 双构建通过；APK 已更新。
 
+## 用户反馈修复 第二十二轮（2026-09-12，7×7 细节增强 + 标注统一 + 卡顿根因）
+
+用户第四轮实机反馈（四点）：移植 7×7 局部细节增强；分析界面标点没对齐；
+实时界面与照片的标注风格必须**完全一致**（"就像直接从实时界面截图"），
+最高最低用 `min`/`max` 标注；实时画面还是卡。
+
+### 1) 卡顿根因（本轮最有价值的发现，已量化）
+
+先前只靠 `dumpsys gfxinfo`（显示 7.26% janky）猜原因，但**它根本看不到热像画面**：
+热像走 `SurfaceView.lockCanvas()` 软件画布，gfxinfo 只统计 Compose 层
+（实测 5 秒内只记到 28 帧，而流本身在 15fps）。于是给渲染线程加了自测量日志
+（`MAG160C/render: paints=N avg=... worst=...`），一测即见真相：
+
+| 阶段 | 绘制帧率 | 单帧绘制耗时 |
+|------|---------|------------|
+| 修复前 | **6.5 帧/秒** | **134 ms** |
+| 加硬件画布后 | **15.1 帧/秒** | **6.4 ms** |
+
+根因：`SurfaceHolder.lockCanvas()` 返回**软件**画布，于是每帧都在 CPU 上做
+320×240 → 约 810×1080 的双线性放大 + 手工清整屏（约 10MB）。
+**改用 `lockHardwareCanvas()`（API 29+，旧系统自动回退软件路径）**，放大与清屏
+交给 GPU，CPU 只剩 76800 像素的拷贝。相机 15fps 因此第一次能完整到达屏幕。
+
+配套修掉的每帧垃圾（卡顿的次要来源，也是 GC 停顿的来源）：
+- `setFramePixels` 每帧 `IntArray(320*240)`（4.6MB/s 垃圾）→ 复用 `flipped`
+- 色条每帧 new 96 个 `Paint` + 96 次 `drawRect` → 预渲染 1×96 位图，仅换色板时重建
+- 标记列表每帧 new ArrayList → 复用
+- 温度点名 `refreshTemps()` 原本在**主线程**（LaunchedEffect 驱动）：
+  400ms 一次分配 19200 整型数组 + 全屏扫描 + `copyNuc`（持渲染线程的锁）
+  → 移到后台 `Dispatchers.Default` 循环，结果经 `Dispatchers.Main` 发布
+
+### 2) 标注统一（照片 = 实时截图）
+
+- 新增 `core/AnnotSpec.kt`（唯一几何定义）+ `media/MarkerPainter.kt`（唯一绘制例程），
+  实时/分析/照片/视频四处共用。此前各画各的，所以"看起来不一样"。
+- 极端值标签由 高/低 改为 **`max` / `min`**（用户指定）。
+- 照片以**传感器朝向**保存（4:3 横），文字在该帧内水平，3 倍分辨率（文字清晰）。
+
+### 3) 分析界面标点对齐（两个真实 bug）
+
+1. **极端值没有走坐标映射**：probes 经 `sensorToPhoto` 转换，extremes 却被
+   **原样加入**（`marks.addAll(extremes)`）。传感器坐标是 0..159/0..119，在
+   960×720 的照片上就落在**左上角几十像素内**——真机照片实测两个 min/max
+   全挤在左上角。已改为同一映射。
+2. **`annotateJpeg` 忽略照片镜像**：从分析界面另存时，标记按未镜像坐标烧录，
+   于是**镜像到另一侧**。已加 `mirror` 参数并走 `sensorToPhoto`。
+
+### 4) 标签互相压字（真机照片可见）
+
+`min 21.9℃` 与 `max 32.6℃` 印在一起成一团。`placeLabel` 只判边界不判重叠，
+现已支持"已放置盒"列表：默认右置 → 被占则翻到左侧 → 仍冲突则下移让位，
+并保证始终在画面内。`MarkerPainter` 一次调用内跟踪，分析界面改为把 probes 与
+extremes **合并成一次 draw**（原来分两次调用，彼此看不见）。
+
+### 5) 重复的 min 标记（分析页 vs 照片）
+
+分析页重新扫描 NUC 推导极值，与拍摄时 live 扫描的结果**不可能逐位一致**
+（传感器在拍摄与重载之间会漂移，平坦区 argmin 极易移位）——真机出现
+两个相距几像素、22.0/22.1℃ 的 min。已在容器新增
+`BLOCK_EXTREMES (0x5BB5B562)`：拍摄时把 minPos/maxPos/minMc/maxMc 一并存盘，
+分析页优先采用，从而与照片上烧录的标记**完全相同**。另存新照片也继续携带。
+
+### 6) 分析页测量面板被导航栏遮住
+
+`UiInsets.navPx` 是普通 `var` 且初值 0，全屏覆盖层（分析查看器）读它时
+拿到的是首帧值 0，于是底部面板落在导航栏之下（截图可见数值不可见）。
+已改为 `mutableStateOf` 并让分析查看器 `padding(bottom = navPx)`。
+
+### 7) 7×7 局部细节增强（官方同款）
+
+按反编译的 `CFunctions::FilterDetailEnhancement_Simple` + `LocalMap7x7_Simple`
+移植（`core/DetailEnhance.kt`）：7×7 窗口按 4×4 抽样（x/y 步长 2），
+`mean = sum >> 4`，`if (strength <= (max-min)*32)` 时
+`detail = (0x8000/divisor)*(center-mean)`，最后 `gray += (k*detail) >> 15`。
+管线位置与官方一致：`grayMap → 细节增强 → upscale2x → 调色板`。
+强度换算经官方 SDK 核对：`MAG_SetDetailEnhancement` 把等级钳到 0..32，
+调用方传 `level << 3`——**与本实现 `level shl 3` 完全一致**。
+设置页新增"图像增强"（关闭/1–4 级），**默认关闭**（无官方参考输出可逐位比对，
+故 opt-in）。默认关闭时 `RenderPipelineTest` 的逐位基线不受影响（96 项测试全绿）。
+
+实机实测：级别 2 下仍 15.1fps，单帧绘制 11.3ms（滤波器约 +5ms，帧预算 66ms 内），
+细节增强清晰可见。
+
+**本轮真机验证（小米 22041211AL / Android 12 / MIUI，无线 adb 192.168.88.137:44323）**：
+
+- [x] 渲染帧率 6.5 → **15.1 帧/秒**，单帧 134ms → **6.4ms**（开增强 11.3ms）
+- [x] 拍照：`capture: nuc=yes probes=2 mirror(h=false,v=true) extremes=2 saved=true`
+- [x] 照片上标记风格与实时界面一致（同一 MarkerPainter），`max 32.6℃` 在热区、
+      `min 22.0℃` 在冷区、Pt1/Pt2 带白底标签，互不压字
+- [x] 分析界面：标点与照片烧录位置对齐，**只有一个 min、一个 max**
+- [x] 分析面板数值可见且与照片一致（最高 32.9 / 最低 22.0 / 中心 24.4℃）
+- [x] 图像增强 2 级：画面细节明显增强，帧率不掉
+
+**教训记录**：
+- `dumpsys gfxinfo` 不统计 SurfaceView 的 lockCanvas 绘制。判断自绘画面性能
+  必须自己打点（本轮加的 `MAG160C/render` 日志就是为此，已保留）。
+- 断言"某处卡"之前先量出**每帧耗时**和**实际帧率**：本轮原以为是温度扫描
+  （主线程 400ms 扫描）导致，量化后才发现是软件画布放大，量级差 20 倍。
+
 ## 用户反馈修复 第二十一轮（2026-09-12，无线 adb 真机调试：根因是 launchMode）
 
 **本轮最大的发现**：前几轮反复出现的"连接风暴/重连循环/相机每 2 秒重枚举"