process_pipeline: Store a default whitelevel in the DNG file

This helps unpacked 10-bit formats, as otherwise applications
assume the image to be 16-bit because of TIFFTAG_BITSPERSAMPLE.

src/camera.c

@@ -122,6 +122,28 @@ mp_pixel_format_bits_per_pixel(MPPixelFormat pixel_format)
 	}
 }
 
+uint32_t
+mp_pixel_format_pixel_depth(MPPixelFormat pixel_format)
+{
+	g_return_val_if_fail(pixel_format < MP_PIXEL_FMT_MAX, 0);
+	switch (pixel_format) {
+	case MP_PIXEL_FMT_BGGR8:
+	case MP_PIXEL_FMT_GBRG8:
+	case MP_PIXEL_FMT_GRBG8:
+	case MP_PIXEL_FMT_RGGB8:
+	case MP_PIXEL_FMT_UYVY:
+	case MP_PIXEL_FMT_YUYV:
+		return 8;
+	case MP_PIXEL_FMT_GBRG10P:
+	case MP_PIXEL_FMT_GRBG10P:
+	case MP_PIXEL_FMT_RGGB10P:
+	case MP_PIXEL_FMT_BGGR10P:
+		return 10;
+	default:
+		return 0;
+	}
+}
+
 uint32_t
 mp_pixel_format_width_to_bytes(MPPixelFormat pixel_format, uint32_t width)
 {

src/camera.h

@@ -30,6 +30,7 @@ uint32_t mp_pixel_format_to_v4l_pixel_format(MPPixelFormat pixel_format);
 uint32_t mp_pixel_format_to_v4l_bus_code(MPPixelFormat pixel_format);
 
 uint32_t mp_pixel_format_bits_per_pixel(MPPixelFormat pixel_format);
+uint32_t mp_pixel_format_pixel_depth(MPPixelFormat pixel_format);
 uint32_t mp_pixel_format_width_to_bytes(MPPixelFormat pixel_format, uint32_t width);
 uint32_t mp_pixel_format_width_to_colors(MPPixelFormat pixel_format, uint32_t width);
 uint32_t mp_pixel_format_height_to_colors(MPPixelFormat pixel_format,

src/process_pipeline.c

@@ -427,9 +427,11 @@ process_image_for_capture(const uint8_t *image, int count)
 	TIFFSetField(tif, TIFFTAG_CFAPATTERN, 4, "\002\001\001\000"); // BGGR
 #endif
 	printf("TIFF version %d\n", TIFFLIB_VERSION);
-	if (camera->whitelevel) {
-		TIFFSetField(tif, TIFFTAG_WHITELEVEL, 1, &camera->whitelevel);
+	int whitelevel = camera->whitelevel;
+	if (!whitelevel) {
+		whitelevel = (1 << mp_pixel_format_pixel_depth(mode.pixel_format)) - 1;
 	}
+	TIFFSetField(tif, TIFFTAG_WHITELEVEL, 1, &whitelevel);
 	if (camera->blacklevel) {
 		const float blacklevel = camera->blacklevel;
 		TIFFSetField(tif, TIFFTAG_BLACKLEVEL, 1, &blacklevel);