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Extend the search space for GetBestGreenRedToBlue

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Get back some of the compression gains by extending the search space for
GetBestGreenRedToBlue. Also removed the SkipRepeatedPixels call, as it was not
helping much in yielding better compression density.

Before:
 1000 files, 63530337 pixels, 1 loops => 45.0s (45.0 ms/file/iterations)
 Compression (output/input): 2.463/3.268 bpp, Encode rate (raw data): 1.347 MP/s

After:
1000 files, 63530337 pixels, 1 loops => 45.9s (45.9 ms/file/iterations)
 Compression (output/input): 2.461/3.268 bpp, Encode rate (raw data): 1.321 MP/s

Change-Id: I044ba9d3f5bec088305e94a7c40c053ca237fd9d
This commit is contained in:
Vikas Arora 2014-03-14 09:54:58 -07:00
parent 1c58526fe1
commit 312e638f30
1 changed files with 2 additions and 27 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

29
src/dsp/lossless.c
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@ -892,25 +892,6 @@ static WEBP_INLINE uint8_t TransformColorBlue(uint8_t green_to_blue,
return (new_blue & 0xff);
}
static WEBP_INLINE int SkipRepeatedPixels(const uint32_t* const argb,
int ix, int xsize) {
const uint32_t v = argb[ix];
if (ix >= 3) {
if (v == argb[ix - 3] && v == argb[ix - 2] && v == argb[ix - 1]) {
return 1;
}
if (ix >= xsize + 3) {
if (v == argb[ix - xsize] &&
argb[ix - 3] == argb[ix - xsize - 3] &&
argb[ix - 2] == argb[ix - xsize - 2] &&
argb[ix - 1] == argb[ix - xsize - 1]) {
return 1;
}
}
}
return 0;
}
static float PredictionCostCrossColor(const int accumulated[256],
const int counts[256]) {
// Favor low entropy, locally and globally.
@ -931,9 +912,6 @@ static float GetPredictionCostCrossColorRed(
int ix = all_y * xsize + tile_x_offset;
int all_x;
for (all_x = tile_x_offset; all_x < all_x_max; ++all_x, ++ix) {
if (SkipRepeatedPixels(argb, ix, xsize)) {
continue;
}
++histo[TransformColorRed(green_to_red, argb[ix])]; // red.
}
}
@ -1001,9 +979,6 @@ static float GetPredictionCostCrossColorBlue(
int all_x;
int ix = all_y * xsize + tile_x_offset;
for (all_x = tile_x_offset; all_x < all_x_max; ++all_x, ++ix) {
if (SkipRepeatedPixels(argb, ix, xsize)) {
continue;
}
++histo[TransformColorBlue(green_to_blue, red_to_blue, argb[ix])];
}
}
@ -1039,8 +1014,8 @@ static void GetBestGreenRedToBlue(
const int step = (quality < 25) ? 32 : (quality > 50) ? 8 : 16;
const int min_green_to_blue = -32;
const int max_green_to_blue = 32;
const int min_red_to_blue = -16;
const int max_red_to_blue = 16;
const int min_red_to_blue = -32;
const int max_red_to_blue = 32;
const int num_iters =
(1 + (max_green_to_blue - min_green_to_blue) / step) *
(1 + (max_red_to_blue - min_red_to_blue) / step);