comment was wrong way around... code was right.

stb_image_write.h

@@ -181,7 +181,7 @@ int stbi_write_tga(char const *filename, int x, int y, int comp, const void *dat
 {
    int has_alpha = !(comp & 1);
    int colorbytes = comp - has_alpha;
-   int format = colorbytes < 2 ? 3 : 2; // 3 color channels (RGB/RGBA) = 3, 1 color channel (Y/YA) = 2
+   int format = colorbytes < 2 ? 3 : 2; // 3 color channels (RGB/RGBA) = 2, 1 color channel (Y/YA) = 3
    if (format == 2) colorbytes = 3;     // is 2 color channels (RG/RGA) even possible? write as RGB/RGBA
    return outfile(filename, -1,-1, x, y, comp, (void *) data, has_alpha, 0,
                   "111 221 2222 11", 0,0,format, 0,0,0, 0,0,x,y, (colorbytes+has_alpha)*8, has_alpha*8);