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Add a WebPExtractAlpha function to dsp

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This is the opposite of WebPDispatchAlpha

+ Implement the SSE2 version

Change-Id: I0c297309255f508c5261da8aad01f7e57f924d6c
This commit is contained in:
Pascal Massimino
2014-09-15 08:11:36 +02:00
parent 0716a98eb3
commit cddd334050
3 changed files with 73 additions and 1 deletions
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8
src/dsp/dsp.h
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@ -268,13 +268,19 @@ extern void (*WebPApplyAlphaMultiply)(
extern void (*WebPApplyAlphaMultiply4444)(
uint8_t* rgba4444, int w, int h, int stride);
// Dispatch the values from alpha[] plane to the ARGB destination 'dst'.
// Returns true if alpha[] plane has non-trivial values different from 0xff.
extern int (*WebPDispatchAlpha)(const uint8_t* alpha, int alpha_stride,
int width, int height,
uint8_t* dst, int dst_stride);
// Extract the alpha values from 32b values in argb[] and pack them into alpha[]
// (this is the opposite of WebPDispatchAlpha).
// Returns true if there's only trivial 0xff alpha values.
extern int (*WebPExtractAlpha)(const uint8_t* argb, int argb_stride,
int width, int height,
uint8_t* alpha, int alpha_stride);
// Pre-Multiply operation transforms x into x * A / 255 (where x=Y,R,G or B).
// Un-Multiply operation transforms x into x * 255 / A.