dany/libwebp
1
0
Fork 0
mirror of https://github.com/webmproject/libwebp.git synced 2025-10-31 02:15:42 +01:00
Code Issues Actions Packages Projects Releases Wiki Activity

move some RGB->YUV functions to yuv.h

Browse Source 
will be needed later

Change-Id: I6b9e460db2d398b9fecd5d3c1bbdb3f2f3d4f5db
This commit is contained in:
Pascal Massimino
2012-08-02 17:23:02 -07:00
parent 4b71ba035a
commit f94b04f045
2 changed files with 39 additions and 34 deletions
Download Patch File Download Diff File Expand all files Collapse all files

33
src/dsp/yuv.h
View File

@@ -5,7 +5,7 @@
// Additional IP Rights Grant: http://www.webmproject.org/license/additional/
// -----------------------------------------------------------------------------
//
// inline YUV->RGB conversion function
// inline YUV<->RGB conversion function
//
// Author: Skal (pascal.massimino@gmail.com)
@@ -14,6 +14,9 @@
#include "../dec/decode_vp8.h"
//------------------------------------------------------------------------------
// YUV -> RGB conversion
#if defined(__cplusplus) || defined(c_plusplus)
extern "C" {
#endif
@@ -95,6 +98,34 @@ static WEBP_INLINE uint32_t VP8Clip4Bits(uint8_t c) {
// Must be called before everything, to initialize the tables.
void VP8YUVInit(void);
//------------------------------------------------------------------------------
// RGB -> YUV conversion
// The exact naming is Y'CbCr, following the ITU-R BT.601 standard.
// More information at: http://en.wikipedia.org/wiki/YCbCr
// Y = 0.2569 * R + 0.5044 * G + 0.0979 * B + 16
// U = -0.1483 * R - 0.2911 * G + 0.4394 * B + 128
// V = 0.4394 * R - 0.3679 * G - 0.0715 * B + 128
// We use 16bit fixed point operations.
static WEBP_INLINE int VP8ClipUV(int v) {
v = (v + (257 << (YUV_FIX + 2 - 1))) >> (YUV_FIX + 2);
return ((v & ~0xff) == 0) ? v : (v < 0) ? 0 : 255;
}
static WEBP_INLINE int VP8RGBToY(int r, int g, int b) {
const int kRound = (1 << (YUV_FIX - 1)) + (16 << YUV_FIX);
const int luma = 16839 * r + 33059 * g + 6420 * b;
return (luma + kRound) >> YUV_FIX; // no need to clip
}
static WEBP_INLINE int VP8RGBToU(int r, int g, int b) {
return VP8ClipUV(-9719 * r - 19081 * g + 28800 * b);
}
static WEBP_INLINE int VP8RGBToV(int r, int g, int b) {
return VP8ClipUV(+28800 * r - 24116 * g - 4684 * b);
}
#if defined(__cplusplus) || defined(c_plusplus)
} // extern "C"
#endif

40
src/enc/picture.c
View File

@@ -17,6 +17,7 @@
#include "../utils/rescaler.h"
#include "../utils/utils.h"
#include "../dsp/dsp.h"
#include "../dsp/yuv.h"
#if defined(__cplusplus) || defined(c_plusplus)
extern "C" {
@@ -544,33 +545,6 @@ int WebPPictureHasTransparency(const WebPPicture* picture) {
//------------------------------------------------------------------------------
// RGB -> YUV conversion
// The exact naming is Y'CbCr, following the ITU-R BT.601 standard.
// More information at: http://en.wikipedia.org/wiki/YCbCr
// Y = 0.2569 * R + 0.5044 * G + 0.0979 * B + 16
// U = -0.1483 * R - 0.2911 * G + 0.4394 * B + 128
// V = 0.4394 * R - 0.3679 * G - 0.0715 * B + 128
// We use 16bit fixed point operations.
enum { YUV_FRAC = 16 };
static WEBP_INLINE int clip_uv(int v) {
v = (v + (257 << (YUV_FRAC + 2 - 1))) >> (YUV_FRAC + 2);
return ((v & ~0xff) == 0) ? v : (v < 0) ? 0 : 255;
}
static WEBP_INLINE int rgb_to_y(int r, int g, int b) {
const int kRound = (1 << (YUV_FRAC - 1)) + (16 << YUV_FRAC);
const int luma = 16839 * r + 33059 * g + 6420 * b;
return (luma + kRound) >> YUV_FRAC; // no need to clip
}
static WEBP_INLINE int rgb_to_u(int r, int g, int b) {
return clip_uv(-9719 * r - 19081 * g + 28800 * b);
}
static WEBP_INLINE int rgb_to_v(int r, int g, int b) {
return clip_uv(+28800 * r - 24116 * g - 4684 * b);
}
// TODO: we can do better than simply 2x2 averaging on U/V samples.
#define SUM4(ptr) ((ptr)[0] + (ptr)[step] + \
@@ -584,8 +558,8 @@ static WEBP_INLINE int rgb_to_v(int r, int g, int b) {
const int r = SUM(r_ptr + src); \
const int g = SUM(g_ptr + src); \
const int b = SUM(b_ptr + src); \
picture->u[dst] = rgb_to_u(r, g, b); \
picture->v[dst] = rgb_to_v(r, g, b); \
picture->u[dst] = VP8RGBToU(r, g, b); \
picture->v[dst] = VP8RGBToV(r, g, b); \
}
#define RGB_TO_UV0(x_in, x_out, y, SUM) { \
@@ -594,8 +568,8 @@ static WEBP_INLINE int rgb_to_v(int r, int g, int b) {
const int r = SUM(r_ptr + src); \
const int g = SUM(g_ptr + src); \
const int b = SUM(b_ptr + src); \
picture->u0[dst] = rgb_to_u(r, g, b); \
picture->v0[dst] = rgb_to_v(r, g, b); \
picture->u0[dst] = VP8RGBToU(r, g, b); \
picture->v0[dst] = VP8RGBToV(r, g, b); \
}
static void MakeGray(WebPPicture* const picture) {
@@ -633,7 +607,7 @@ static int ImportYUVAFromRGBA(const uint8_t* const r_ptr,
for (x = 0; x < width; ++x) {
const int offset = step * x + y * rgb_stride;
picture->y[x + y * picture->y_stride] =
rgb_to_y(r_ptr[offset], g_ptr[offset], b_ptr[offset]);
VP8RGBToY(r_ptr[offset], g_ptr[offset], b_ptr[offset]);
}
}
@@ -643,7 +617,7 @@ static int ImportYUVAFromRGBA(const uint8_t* const r_ptr,
for (x = 0; x < (width >> 1); ++x) {
RGB_TO_UV(x, y, SUM4);
}
if (picture->width & 1) {
if (width & 1) {
RGB_TO_UV(x, y, SUM2V);
}
}