roundingdither

1 files changed, 7 insertions, 0 deletions

diff --git a/pixman/pixman-bits-image.c b/pixman/pixman-bits-image.c
index 372c0b2f..cbf2178a 100644
--- a/pixman/pixman-bits-image.c
+++ b/pixman/pixman-bits-image.c
@@ -2598,6 +2598,13 @@ dest_write_back_narrow (pixman_iter_t *iter)
      *      deeper. For example, compare: #142b3d -> #457262. Or
      *      #000000 -> #39213e. Gimp renders these without banding, but when
      *      evaluated in 8 bits, they look ugly.
+     *
+     *    - When converting the dither signal to the correct number of bits,
+     *      that should ideally be done with rounding, not bitshifting.
+     *      With that, the 565 gradient becomes close to indistinguishable
+     *      from the 8888 one. Note that one bug that can happen is a wavy
+     *      colored pattern; I think this happens if the algorithm for g is
+     *      different from the one for r and b.
      */
     if (image->common.dither == PIXMAN_DITHER_ENABLE)
     {