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Merge "Improved alpha cleanup for the webp encoder when prediction transform is used."

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This commit is contained in:
Pascal Massimino
2015-12-08 11:32:37 +00:00
committed by Gerrit Code Review
parent fb8c9106c7 6938111357
commit 7eb01ff3e8
4 changed files with 34 additions and 11 deletions
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5
src/enc/alpha.c
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@ -67,6 +67,11 @@ static int EncodeLossless(const uint8_t* const data, int width, int height,
WebPConfigInit(&config);
config.lossless = 1;
// Enable exact, or it would alter RGB values of transparent alpha, which is
// normally OK but not here since we are not encoding the input image but an
// internal encoding-related image containing necessary exact information in
// RGB channels.
config.exact = 1;
config.method = effort_level; // impact is very small
// Set a low default quality for encoding alpha. Ensure that Alpha quality at
// lower methods (3 and below) is less than the threshold for triggering

3
src/enc/vp8l.c
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@ -1012,7 +1012,8 @@ static WebPEncodingError ApplyPredictFilter(const VP8LEncoder* const enc,
const int transform_height = VP8LSubSampleSize(height, pred_bits);
VP8LResidualImage(width, height, pred_bits, low_effort, enc->argb_,
enc->argb_scratch_, enc->transform_data_);
enc->argb_scratch_, enc->transform_data_,
enc->config_->exact);
VP8LPutBits(bw, TRANSFORM_PRESENT, 1);
VP8LPutBits(bw, PREDICTOR_TRANSFORM, 2);
assert(pred_bits >= 2);