app+csdk+docs: 按反汇编定案修复——官方安卓路径无 160→320 插值级（ImageViewer 无 FILTER_BITMAP 最近邻放大），我们的双线性 2× 自造交错细纹；实测冷区细条纹比 1.16/1.29→1.00/0.93，csdk 同加 upscale_nearest，119 单测全绿

csdk/README.md

@@ -301,6 +301,10 @@ build-artifacts\csdk_test_display.exe
    同场景照片逐像素平均差 4.5/255、逐计数中位差 2 级，见 §10/§11）。
    ⚠️ **本机没有 C 编译器**（gcc/clang/NDK 都没有），所以这段 C **未编译**——
    算法本身由 Kotlin golden 测试锁定，合入前请在带编译器的环境编译 + 跑回归。
+   - 同一节还有个 `upscale_nearest`：官方**安卓**路径没有 160→320 的插值级
+     （SDK 给 App 的位图就是 160×120，App 用 `new Paint(1)`（无 FILTER_BITMAP）最近邻放大），
+     而 PC 版的双线性会展出一层"全幅/半幅"交错细纹（暗/低温区最明显）。
+     真机实测：冷区细尺度列条纹比 1.16/1.29（双线性）→ **1.00/0.93**（最近邻）。
    - 顺带（同一条链）：**曲线插值温度要加 `BasePara2.fpaTempFix`**。官方 App 传给 SDK 的是
      `帧尾 FPA + fpaTempFix`（真机 1699），`SelectCaliCurve`/`GenerateVolatileLens`
      用它选/插值每像素标定表；温度换算链路仍用帧尾原值。C 侧**已实现**

csdk/include/mag160c/mag160c_render.h

@@ -60,6 +60,14 @@ typedef struct mag160c_render_cfg_t {
     int fpa_temp_fix;
     /* Brightness offset for the Android LUT base; the official app passes 0. */
     int lut_brightness;
+    /* 1 = replicate pixels in the 160x120 -> 320x240 stage instead of interpolating.
+       The official ANDROID path has no such stage at all (its SDK hands the app a
+       160x120 bitmap which ImageViewer draws with a non-filtering paint = nearest),
+       while the PC SDK's bilinear version fabricates an interleaved full/half
+       amplitude column pattern at the sensor Nyquist - visible as extra fine stripes
+       in the dark/cold regions.  Measured on device: fine-scale cold-region stripe
+       ratio vs the official 1.16-1.29x (bilinear) -> 1.00/0.93 (nearest). */
+    int upscale_nearest;
     mag160c_render_ffc_cb_t ffc_cb;
     void *ffc_user;
     mag160c_render_post_nuc_cb_t post_nuc_cb;

csdk/src/mag160c_render.c

@@ -59,7 +59,7 @@ struct mag160c_render_t {
     mag160c_render_post_gray_cb_t post_gray_cb;
     void *post_gray_user;
     int ffc_period, ffc_drift, warm_frames, cdf_pivot_75, force75;
-    int android_lut, fpa_temp_fix, lut_brightness;
+    int android_lut, fpa_temp_fix, lut_brightness, upscale_nearest;
 };
 
 static int counts_to_temp_mc(int counts) {
@@ -524,6 +524,19 @@ static void upscale2x(mag160c_render_t *r) {
     const unsigned char *s = r->gray160;
     unsigned char *o = r->gray320;
     int W = r->w, H = r->h, W2 = W * 2;
+    if (r->upscale_nearest) {
+        /* Android parity: no interpolation stage (see mag160c_render.h) */
+        for (int y = 0; y < H; ++y) {
+            const unsigned char *row = s + y * W;
+            unsigned char *o0 = o + y * W2 * 2, *o1 = o0 + W2;
+            for (int x = 0; x < W; ++x) {
+                unsigned char v = row[x];
+                o0[x * 2] = v; o0[x * 2 + 1] = v;
+                o1[x * 2] = v; o1[x * 2 + 1] = v;
+            }
+        }
+        return;
+    }
     for (int y = 0; y < H - 1; ++y) {
         const unsigned char *r0 = s + y * W, *r1 = r0 + W;
         unsigned char *o0 = o + y * W2 * 2, *o1 = o0 + W2;
@@ -667,6 +680,7 @@ mag160c_error_t mag160c_render_init(mag160c_render_t **out,
     r->android_lut = cfg->android_lut;
     r->fpa_temp_fix = cfg->fpa_temp_fix;
     r->lut_brightness = cfg->lut_brightness;
+    r->upscale_nearest = cfg->upscale_nearest;
     r->force75 = cfg->startup_force_ffc;
     r->dev24 = 5;
     r->dev4c_shift = 3;

csdk/tools/mag160c_demo3.c

@@ -618,6 +618,7 @@ int WINAPI WinMain(HINSTANCE inst, HINSTANCE prev, LPSTR cmd, int show) {
     cfg.cdf_pivot_75 = 1;      /* kept for the PC path */
     cfg.android_lut = 1;
     cfg.fpa_temp_fix = 1699;   /* BasePara2.fpaTempFix of device 160043865 */
+    cfg.upscale_nearest = 1;   /* official Android path has no interpolating 2x stage */
     cfg.ffc_cb = ffc_cb;
     cfg.post_nuc_cb = post_nuc_cb;
     cfg.post_gray_cb = post_gray_cb;

csdk/tools/mag160c_linux_demo.c

@@ -134,6 +134,7 @@ int main(int argc, char **argv) {
     cfg.cdf_pivot_75 = 1;      /* kept for the PC path */
     cfg.android_lut = 1;
     cfg.fpa_temp_fix = 1699;   /* BasePara2.fpaTempFix of device 160043865 */
+    cfg.upscale_nearest = 1;   /* official Android path has no interpolating 2x stage */
     cfg.ffc_cb = ffc_cb;
     mag160c_render_t *render = NULL;
     if (mag160c_render_init(&render, &cfg) != MAG160C_OK) {