postprocessor: disallow GPUJPEG_NONE internal CS

If param_image->color_space == GPUJPEG_NONE (which has been
semi-officially used for native decode keeping CS) set the
color_space to color_space_internal (never GPUJPEG_NONE)
by gpujpeg_reader.

Now run the null CS conversion only when direct memcpy still cannot be
used and color_space_internal == param_image.color_space (still using
GPUJPEG_NONE as template param - if GPUJPEG_NONE is in either src or
dst specialization, null conversion is used).

Author: MartinPulec

src/gpujpeg_postprocessor.cu

@@ -343,12 +343,8 @@ gpujpeg_preprocessor_select_decode_kernel(struct gpujpeg_coder* coder)
         RETURN_KERNEL_SWITCH(PIXEL_FORMAT, COLOR, GPUJPEG_DYNAMIC, GPUJPEG_DYNAMIC, GPUJPEG_DYNAMIC, GPUJPEG_DYNAMIC, GPUJPEG_DYNAMIC, GPUJPEG_DYNAMIC, GPUJPEG_DYNAMIC, GPUJPEG_DYNAMIC) \
     } \
 
-    // None color space
-    if ( coder->param_image.color_space == GPUJPEG_NONE ) {
-        RETURN_KERNEL(coder->param_image.pixel_format, GPUJPEG_NONE)
-    }
     // RGB color space
-    else if ( coder->param_image.color_space == GPUJPEG_RGB ) {
+    if ( coder->param_image.color_space == GPUJPEG_RGB ) {
         RETURN_KERNEL(coder->param_image.pixel_format, GPUJPEG_RGB)
     }
     // YCbCr color space
@@ -422,7 +418,7 @@ gpujpeg_preprocessor_decoder_init(struct gpujpeg_coder* coder)
 
     // assert(coder->param.comp_count == 3 || coder->param.comp_count == 4);
 
-    if (coder->param.color_space_internal == GPUJPEG_NONE) {
+    if (coder->param.color_space_internal == coder->param_image.color_space) {
         coder->preprocessor = (void*)gpujpeg_preprocessor_select_decode_kernel<GPUJPEG_NONE>(coder);
     }
     else if (coder->param.color_space_internal == GPUJPEG_RGB) {

src/gpujpeg_reader.c

@@ -1480,9 +1480,14 @@ adjust_pixel_format(struct gpujpeg_parameters * param, struct gpujpeg_image_para
 }
 
 static void
-adjust_format(struct gpujpeg_parameters* param, struct gpujpeg_image_parameters* param_image)
+adjust_format(struct gpujpeg_parameters* param, struct gpujpeg_image_parameters* param_image,
+              enum gpujpeg_color_space color_space_internal)
 {
     static_assert(GPUJPEG_PIXFMT_AUTODETECT < 0, "enum gpujpeg_pixel_format type should be signed");
+    if ( param_image->color_space == GPUJPEG_NONE) {
+        param_image->color_space = color_space_internal;
+    }
+
     if ( param_image->color_space == GPUJPEG_CS_DEFAULT ) {
         if ( param_image->pixel_format == GPUJPEG_U8 ||
              (param_image->pixel_format <= GPUJPEG_PIXFMT_AUTODETECT && param->comp_count == 1) ) {
@@ -1569,7 +1574,7 @@ gpujpeg_reader_read_image(struct gpujpeg_decoder* decoder, uint8_t* image, size_
                                           image_end) != 0 ) {
                 return -1;
             }
-            adjust_format(&reader.param, &reader.param_image);
+            adjust_format(&reader.param, &reader.param_image, reader.param.color_space_internal);
             break;
 
         case GPUJPEG_MARKER_DHT: