dany/libwebp
1
0
Fork 0
mirror of https://github.com/webmproject/libwebp.git synced 2025-01-15 17:18:23 +01:00
Code Issues Actions Packages Projects Releases Wiki Activity

Tune HistogramCombineBin for large images.

Browse Source 
Tune HistogramCombineBin for hard images that are larger than 1-2 Mega
pixel and represent photographic images.

This speeds up lossless encoding on 1000 image corpus by 10-12% and compression
penalty of 0.1-0.2%.

Change-Id: Ifd03b75c503b9e886098e5fe6f86be0391ca8e81
This commit is contained in:
Vikas Arora 2014-03-28 07:06:54 -07:00
parent af93bdd6bc
commit 6af6b8e1b6
1 changed files with 16 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

20
src/enc/histogram.c
View File

@ -561,8 +561,8 @@ static void HistogramCompactBins(VP8LHistogramSet* const histo_image) {
} }
static void HistogramCombineBin(VP8LHistogramSet* const histo_image, static void HistogramCombineBin(VP8LHistogramSet* const histo_image,
VP8LHistogram* const histos, VP8LHistogram* const histos, int bin_depth,
int bin_depth, double combine_cost_factor,
int16_t* const bin_map) { int16_t* const bin_map) {
int bin_id; int bin_id;
VP8LHistogram* cur_combo = histos; VP8LHistogram* cur_combo = histos;
@ -576,7 +576,7 @@ static void HistogramCombineBin(VP8LHistogramSet* const histo_image,
const int idx2 = bin_map[bin_offset + n]; const int idx2 = bin_map[bin_offset + n];
const double bit_cost_idx2 = histo_image->histograms[idx2]->bit_cost_; const double bit_cost_idx2 = histo_image->histograms[idx2]->bit_cost_;
if (bit_cost_idx2 > 0.) { if (bit_cost_idx2 > 0.) {
const double bit_cost_thresh = -bit_cost_idx2 * 0.1; const double bit_cost_thresh = -bit_cost_idx2 * combine_cost_factor;
const double curr_cost_diff = const double curr_cost_diff =
HistogramAddEval(histo_image->histograms[idx1], HistogramAddEval(histo_image->histograms[idx1],
histo_image->histograms[idx2], histo_image->histograms[idx2],
@ -706,6 +706,15 @@ static void HistogramRemap(const VP8LHistogramSet* const init_histo,
} }
} }
static double GetCombineCostFactor(int histo_size, int quality) {
double combine_cost_factor = 0.16;
if (histo_size > 256) combine_cost_factor /= 2.;
if (histo_size > 512) combine_cost_factor /= 2.;
if (histo_size > 1024) combine_cost_factor /= 2.;
if (quality <= 50) combine_cost_factor /= 2.;
return combine_cost_factor;
}
int VP8LGetHistoImageSymbols(int xsize, int ysize, int VP8LGetHistoImageSymbols(int xsize, int ysize,
const VP8LBackwardRefs* const refs, const VP8LBackwardRefs* const refs,
int quality, int histo_bits, int cache_bits, int quality, int histo_bits, int cache_bits,
@ -746,8 +755,11 @@ int VP8LGetHistoImageSymbols(int xsize, int ysize,
HistogramBuild(xsize, histo_bits, refs, init_histo); HistogramBuild(xsize, histo_bits, refs, init_histo);
if (bin_map != NULL) { if (bin_map != NULL) {
const double combine_cost_factor =
GetCombineCostFactor(histo_image_raw_size, quality);
HistogramAnalyzeBin(init_histo, histo_image, bin_map); HistogramAnalyzeBin(init_histo, histo_image, bin_map);
HistogramCombineBin(histo_image, histos, bin_depth, bin_map); HistogramCombineBin(histo_image, histos, bin_depth, combine_cost_factor,
bin_map);
} else { } else {
HistogramAnalyze(init_histo, histo_image); HistogramAnalyze(init_histo, histo_image);
} }