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only apply color-mapping for alpha on the cropped area

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This is only possible if the filtering is not VERTICAL or GRADIENT.
Otherwise, we need the spatial predictors and hence need the un-visible
part above crop_top row.

COLOR_INDEX transform is the only transform that is not predicted
from previous row. Applying the same for other transform (spatial
predict, ...) is going to be more involve and use an extra temporary row.

+ remove ApplyInverseTransformsAlpha()
(work is done directly within ExtractPalettedAlphaRows())

+ change back to using filter_ instead of unfilter_func_

Change-Id: I09e57efae4a4af00bde35f21ca6e3d73b35d7d43
This commit is contained in:
Pascal Massimino
2016-04-07 10:21:02 +02:00
parent aa809cfeb3
commit 95ecccf6dc
3 changed files with 37 additions and 39 deletions
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16
src/dec/alpha.c
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@ -52,11 +52,12 @@ static int ALPHInit(ALPHDecoder* const dec, const uint8_t* data,
const uint8_t* const alpha_data = data + ALPHA_HEADER_LEN;
const size_t alpha_data_size = data_size - ALPHA_HEADER_LEN;
int rsrv;
int filter;
VP8Io* const io = &dec->io_;
assert(data != NULL && output != NULL && src_io != NULL);
VP8FiltersInit();
dec->output_ = output;
dec->width_ = src_io->width;
dec->height_ = src_io->height;
assert(dec->width_ > 0 && dec->height_ > 0);
@ -66,21 +67,17 @@ static int ALPHInit(ALPHDecoder* const dec, const uint8_t* data,
}
dec->method_ = (data[0] >> 0) & 0x03;
filter = (data[0] >> 2) & 0x03;
dec->filter_ = (data[0] >> 2) & 0x03;
dec->pre_processing_ = (data[0] >> 4) & 0x03;
rsrv = (data[0] >> 6) & 0x03;
if (dec->method_ < ALPHA_NO_COMPRESSION ||
dec->method_ > ALPHA_LOSSLESS_COMPRESSION ||
filter >= WEBP_FILTER_LAST ||
dec->filter_ >= WEBP_FILTER_LAST ||
dec->pre_processing_ > ALPHA_PREPROCESSED_LEVELS ||
rsrv != 0) {
return 0;
}
VP8FiltersInit();
dec->unfilter_func_ = WebPUnfilters[filter];
dec->output_ = output;
// Copy the necessary parameters from src_io to io
VP8InitIo(io);
WebPInitCustomIo(NULL, io);
@ -121,8 +118,9 @@ static int ALPHDecode(VP8Decoder* const dec, int row, int num_rows) {
assert(dec->alpha_data_size_ >= ALPHA_HEADER_LEN + offset + num_pixels);
memcpy(dec->alpha_plane_ + offset,
dec->alpha_data_ + ALPHA_HEADER_LEN + offset, num_pixels);
if (alph_dec->unfilter_func_ != NULL) {
alph_dec->unfilter_func_(width, height, width, row, num_rows, output);
if (WebPUnfilters[alph_dec->filter_] != NULL) {
WebPUnfilters[alph_dec->filter_](width, height, width,
row, num_rows, output);
}
} else { // alph_dec->method_ == ALPHA_LOSSLESS_COMPRESSION
assert(alph_dec->vp8l_dec_ != NULL);