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Add smart RGB->YUV conversion option -pre 4

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New function: WebPPictureSmartARGBToYUVA()
This implement smart RGB->YUV conversion.

This is rather undocumented for now, and is triggered using '-pre 4'
preprocessing option.

This is slow-ish and use quite some memory, but should be improvable.
This is somehow a usable beta version.

Change-Id: Ia50a8c30134e4cab8a7d3eb70aef13ce1f6187a1
This commit is contained in:
skal
2014-08-15 10:55:09 -07:00
parent 137e609016
commit 3fc4c539aa
4 changed files with 548 additions and 99 deletions
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26
src/enc/webpenc.c
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@ -328,16 +328,22 @@ int WebPEncode(const WebPConfig* config, WebPPicture* pic) {
VP8Encoder* enc = NULL;
if (pic->y == NULL || pic->u == NULL || pic->v == NULL) {
// Make sure we have YUVA samples.
float dithering = 0.f;
if (config->preprocessing & 2) {
const float x = config->quality / 100.f;
const float x2 = x * x;
// slowly decreasing from max dithering at low quality (q->0)
// to 0.5 dithering amplitude at high quality (q->100)
dithering = 1.0f + (0.5f - 1.0f) * x2 * x2;
}
if (!WebPPictureARGBToYUVADithered(pic, WEBP_YUV420, dithering)) {
return 0;
if (config->preprocessing & 4) {
if (!WebPPictureSmartARGBToYUVA(pic)) {
return 0;
}
} else {
float dithering = 0.f;
if (config->preprocessing & 2) {
const float x = config->quality / 100.f;
const float x2 = x * x;
// slowly decreasing from max dithering at low quality (q->0)
// to 0.5 dithering amplitude at high quality (q->100)
dithering = 1.0f + (0.5f - 1.0f) * x2 * x2;
}
if (!WebPPictureARGBToYUVADithered(pic, WEBP_YUV420, dithering)) {
return 0;
}
}
}