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For alpha compositing consistency, all layers should affect alpha in the

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* app/gegl/gimpoperationadditionmode.c: For alpha compositing
consistency, all layers should affect alpha in the same way
independent of layer mode. Replace the compositing algorithm with
a version without the flaws discovered so far in the previous
ones. Don't use it yet though as it requires premultiplied data.

svn path=/trunk/; revision=27382
This commit is contained in:
Martin Nordholts
2008-10-23 22:14:44 +00:00
parent 8626bed826
commit 06b46fef6d
2 changed files with 18 additions and 1 deletions
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8
ChangeLog
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@ -1,3 +1,11 @@
2008-10-24 Martin Nordholts <martinn@svn.gnome.org>
* app/gegl/gimpoperationadditionmode.c: For alpha compositing
consistency, all layers should affect alpha in the same way
independent of layer mode. Replace the compositing algorithm with
a version without the flaws discovered so far in the previous
ones. Don't use it yet though as it requires premultiplied data.
2008-10-24 Sven Neumann <sven@gimp.org>
* app/paint-funcs/scale-region.c (scale): use the inverse of the

11
app/gegl/gimpoperationadditionmode.c
View File

@ -72,12 +72,21 @@ gimp_operation_addition_mode_process (GeglOperation *operation,
while (samples--)
{
#if 1
// Best so far (maybe even correct?)
// Wrong, for alpha compositing consistency all layers should
// affect alpha in the same way independent of layer mode
out[RED] = in[RED] + layer[RED] * layer[ALPHA];
out[GREEN] = in[GREEN] + layer[GREEN] * layer[ALPHA];
out[BLUE] = in[BLUE] + layer[BLUE] * layer[ALPHA];
out[ALPHA] = in[ALPHA];
#else
// A very nice combination of correctness and speed for
// premultiplied data without any of the issues the previous
// versions had
out[RED] = in[RED] + layer[RED];
out[GREEN] = in[GREEN] + layer[GREEN];
out[BLUE] = in[BLUE] + layer[BLUE];
out[ALPHA] = in[ALPHA] + layer[ALPHA] - in[ALPHA] * layer[ALPHA];
// Wrong, doesn't take layer opacity of Addition-mode layer into
// account
out[RED] = in[RED] + layer[RED];