rest of bbuf printf

[libucw.git] / images / io-libpng.c

diff --git a/images/io-libpng.c b/images/io-libpng.c
index a1705a376a467b044bad77a6f478cd8fec29d612..f15955a64cf83c045bd953cb1afa33fd96908b96 100644 (file)
--- 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;