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| author |  Mike Klein <mtklein@chromium.org> | 2017-06-09 09:32:24 -0400 |
|---|---|---|
| committer |  Skia Commit-Bot <skia-commit-bot@chromium.org> | 2017-06-09 14:18:12 +0000 |
| commit | 39afa1226f71d09bbdb21cc3c86cb23539d8311b (patch) | |
| tree | 1843db3d4e18ddea8256f85f39713db3aedd0b9b /tools/picture_utils.cpp | |
| parent | eb86b7094755a5fc1e49d22b4c5323f372344d61 (diff) | |
fix f16 -> sRGB in encode_bitmap_for_png()
The existing logic looks wrong to me:
- clamp premul to [0,1]
- unpremul, ignoring zero alpha
It seems like we should do:
- unpremul, avoiding any divide by zero
- clamp unpremul to [0,1]
Am I misunderstanding this or has this just always been wrong?
Change-Id: I9636b9566c746bc05371e1e660f4e59dde16827b
Reviewed-on: https://skia-review.googlesource.com/19264
Reviewed-by: Matt Sarett <msarett@google.com>
Commit-Queue: Mike Klein <mtklein@chromium.org>
Diffstat (limited to 'tools/picture_utils.cpp')
| -rw-r--r-- | tools/picture_utils.cpp | 9 |
1 files changed, 5 insertions, 4 deletions
diff --git a/tools/picture_utils.cpp b/tools/picture_utils.cpp index bd32f1938e..db245538d4 100644 --- a/tools/picture_utils.cpp +++ b/tools/picture_utils.cpp @@ -113,10 +113,11 @@ namespace sk_tools { SkHalfToFloat(static_cast<SkHalf>(px[i] >> (1 * 16))), SkHalfToFloat(static_cast<SkHalf>(px[i] >> (2 * 16))), SkHalfToFloat(static_cast<SkHalf>(px[i] >> (3 * 16)))); - fs = Sk4f::Max(0.0f, Sk4f::Min(fs, 1.0f)); // Clamp - float invA = 1.0f / fs[3]; - fs = fs * Sk4f(invA, invA, invA, 1); // Unpremultiply. - rgba[i] = Sk4f_toS32(fs); // Pack down to sRGB bytes. + if (fs[3]) { // Unpremultiply. + fs *= Sk4f(1/fs[3], 1/fs[3], 1/fs[3], 1); + } + fs = Sk4f::Max(0.0f, Sk4f::Min(fs, 1.0f)); // Clamp to [0,1]. + rgba[i] = Sk4f_toS32(fs); // Pack down to sRGB bytes. } } else { |