X-Git-Url: http://mj.ucw.cz/gitweb/?a=blobdiff_plain;ds=sidebyside;f=images%2Fio-libpng.c;h=f15955a64cf83c045bd953cb1afa33fd96908b96;hb=94022b1a1e317871b302946b595b2e890f4f1853;hp=a1705a376a467b044bad77a6f478cd8fec29d612;hpb=bed0e58916a622b1b66f5dedcda121e7e848355b;p=libucw.git

diff --git a/images/io-libpng.c b/images/io-libpng.c
index a1705a37..f15955a6 100644
--- a/images/io-libpng.c
+++ b/images/io-libpng.c
@@ -229,7 +229,7 @@ libpng_read_data(struct image_io *io)
 	    if (io->flags & IMAGE_IO_USE_BACKGROUND)
 	      {
                 png_set_add_alpha(rd->png_ptr, 255, PNG_FILLER_AFTER);
-	        read_flags |= IMAGE_ALPHA;
+	        read_flags = (read_flags | IMAGE_ALPHA) & IMAGE_CHANNELS_FORMAT;
 	      }
 	    else if ((io->flags & IMAGE_PIXEL_FORMAT) == (COLOR_SPACE_RGB | IMAGE_PIXELS_ALIGNED))
               png_set_add_alpha(rd->png_ptr, 255, PNG_FILLER_AFTER);
@@ -251,7 +251,7 @@ libpng_read_data(struct image_io *io)
 	if (!(io->flags & IMAGE_ALPHA))
 	  {
 	    if (io->flags & IMAGE_IO_USE_BACKGROUND)
-	      read_flags |= IMAGE_ALPHA;
+	      read_flags = (read_flags | IMAGE_ALPHA) & IMAGE_CHANNELS_FORMAT;
 	    else
               png_set_strip_alpha(rd->png_ptr);
 	  }  
@@ -267,7 +267,7 @@ libpng_read_data(struct image_io *io)
 	  png_set_rgb_to_gray_fixed(rd->png_ptr, 1, 21267, 71514);
 	if (!(io->flags & IMAGE_ALPHA))
 	  if (io->flags & IMAGE_IO_USE_BACKGROUND)
-	    read_flags |= IMAGE_ALPHA;
+	    read_flags = (read_flags | IMAGE_ALPHA) & IMAGE_CHANNELS_FORMAT;
 	  else if ((io->flags & IMAGE_PIXEL_FORMAT) != (COLOR_SPACE_RGB | IMAGE_PIXELS_ALIGNED))
             png_set_strip_alpha(rd->png_ptr);
 	break;