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| author | Sergey Sharybin <sergey.vfx@gmail.com> | 2013-08-23 12:27:01 +0400 |
|---|---|---|
| committer | Sergey Sharybin <sergey.vfx@gmail.com> | 2013-08-23 12:27:01 +0400 |
| commit | 68592d3cd1a5468a76965861db6ac3223b0bf843 (patch) | |
| tree | 0631094d37906477fabbc4534615b876a4352be5 /source/blender/imbuf/intern/imageprocess.c | |
| parent | 6f4b79d5af8245ad88afbad43a813b6bf238c310 (diff) | |
Fix #36535: Color difference when saving image
Issue was caused by precision loss in alpha under code.
Now it might be slower a bit, but it's as precise as it
could be. At least i hope so :)
Diffstat (limited to 'source/blender/imbuf/intern/imageprocess.c')
| -rw-r--r-- | source/blender/imbuf/intern/imageprocess.c | 14 |
1 files changed, 9 insertions, 5 deletions
diff --git a/source/blender/imbuf/intern/imageprocess.c b/source/blender/imbuf/intern/imageprocess.c index 26dd0f2977a..bde17e17419 100644 --- a/source/blender/imbuf/intern/imageprocess.c +++ b/source/blender/imbuf/intern/imageprocess.c @@ -359,17 +359,21 @@ void IMB_alpha_under_color_byte(unsigned char *rect, int x, int y, float backcol unsigned char *cp = rect; while (a--) { - if (cp[3] == 0) { + if (cp[3] == 255) { + /* pass */ + } + else if (cp[3] == 0) { cp[0] = backcol[0] * 255; cp[1] = backcol[1] * 255; cp[2] = backcol[2] * 255; } else { - int mul = 255 - cp[3]; + float alpha = cp[3] / 255.0; + float mul = 1.0f - alpha; - cp[0] = (cp[0] * cp[3] >> 8) + mul * backcol[0] / 255; - cp[1] = (cp[1] * cp[3] >> 8) + mul * backcol[1] / 255; - cp[2] = (cp[2] * cp[3] >> 8) + mul * backcol[2] / 255; + cp[0] = (cp[0] * alpha) + mul * backcol[0]; + cp[1] = (cp[1] * alpha) + mul * backcol[1]; + cp[2] = (cp[2] * alpha) + mul * backcol[2]; } cp[3] = 255; |