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Merge "add LUT-free reference code for YUV->RGB conversion." into 0.3.0

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This commit is contained in:
James Zern 2013-03-14 18:44:29 -07:00 committed by Gerrit Code Review
commit 0037b2d280
2 changed files with 112 additions and 15 deletions
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8
src/dsp/yuv.c
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@ -15,7 +15,7 @@
extern "C" { extern "C" {
#endif #endif
enum { YUV_HALF = 1 << (YUV_FIX - 1) }; #ifdef WEBP_YUV_USE_TABLE
int16_t VP8kVToR[256], VP8kUToB[256]; int16_t VP8kVToR[256], VP8kUToB[256];
int32_t VP8kVToG[256], VP8kUToG[256]; int32_t VP8kVToG[256], VP8kUToG[256];
@ -62,6 +62,12 @@ void VP8YUVInit(void) {
done = 1; done = 1;
} }
#else
void VP8YUVInit(void) {}
#endif // WEBP_YUV_USE_TABLE
#if defined(__cplusplus) || defined(c_plusplus) #if defined(__cplusplus) || defined(c_plusplus)
} // extern "C" } // extern "C"
#endif #endif

119
src/dsp/yuv.h
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@ -19,8 +19,9 @@
// G = 1.164 * (Y-16) - 0.813 * (V-128) - 0.391 * (U-128) // G = 1.164 * (Y-16) - 0.813 * (V-128) - 0.391 * (U-128)
// B = 1.164 * (Y-16) + 2.018 * (U-128) // B = 1.164 * (Y-16) + 2.018 * (U-128)
// where Y is in the [16,235] range, and U/V in the [16,240] range. // where Y is in the [16,235] range, and U/V in the [16,240] range.
// But the common term 1.164 * (Y-16) can be handled as an offset in the // In the table-lookup version (WEBP_YUV_USE_TABLE), the common factor
// VP8kClip[] table. So the formulae should be read as: // "1.164 * (Y-16)" can be handled as an offset in the VP8kClip[] table.
// So in this case the formulae should be read as:
// R = 1.164 * [Y + 1.371 * (V-128) ] - 18.624 // R = 1.164 * [Y + 1.371 * (V-128) ] - 18.624
// G = 1.164 * [Y - 0.698 * (V-128) - 0.336 * (U-128)] - 18.624 // G = 1.164 * [Y - 0.698 * (V-128) - 0.336 * (U-128)] - 18.624
// B = 1.164 * [Y + 1.733 * (U-128)] - 18.624 // B = 1.164 * [Y + 1.733 * (U-128)] - 18.624
@ -33,6 +34,9 @@
#include "../dec/decode_vp8.h" #include "../dec/decode_vp8.h"
// Define the following to use the LUT-based code:
#define WEBP_YUV_USE_TABLE
#if defined(WEBP_EXPERIMENTAL_FEATURES) #if defined(WEBP_EXPERIMENTAL_FEATURES)
// Do NOT activate this feature for real compression. This is only experimental! // Do NOT activate this feature for real compression. This is only experimental!
// This flag is for comparison purpose against JPEG's "YUVj" natural colorspace. // This flag is for comparison purpose against JPEG's "YUVj" natural colorspace.
@ -51,9 +55,14 @@ extern "C" {
#endif #endif
enum { YUV_FIX = 16, // fixed-point precision enum { YUV_FIX = 16, // fixed-point precision
YUV_HALF = 1 << (YUV_FIX - 1),
YUV_MASK = (256 << YUV_FIX) - 1,
YUV_RANGE_MIN = -227, // min value of r/g/b output YUV_RANGE_MIN = -227, // min value of r/g/b output
YUV_RANGE_MAX = 256 + 226 // max value of r/g/b output YUV_RANGE_MAX = 256 + 226 // max value of r/g/b output
}; };
#ifdef WEBP_YUV_USE_TABLE
extern int16_t VP8kVToR[256], VP8kUToB[256]; extern int16_t VP8kVToR[256], VP8kUToB[256];
extern int32_t VP8kVToG[256], VP8kUToG[256]; extern int32_t VP8kVToG[256], VP8kUToG[256];
extern uint8_t VP8kClip[YUV_RANGE_MAX - YUV_RANGE_MIN]; extern uint8_t VP8kClip[YUV_RANGE_MAX - YUV_RANGE_MIN];
@ -69,6 +78,16 @@ static WEBP_INLINE void VP8YuvToRgb(uint8_t y, uint8_t u, uint8_t v,
rgb[2] = VP8kClip[y + b_off - YUV_RANGE_MIN]; rgb[2] = VP8kClip[y + b_off - YUV_RANGE_MIN];
} }
static WEBP_INLINE void VP8YuvToBgr(uint8_t y, uint8_t u, uint8_t v,
uint8_t* const bgr) {
const int r_off = VP8kVToR[v];
const int g_off = (VP8kVToG[v] + VP8kUToG[u]) >> YUV_FIX;
const int b_off = VP8kUToB[u];
bgr[0] = VP8kClip[y + b_off - YUV_RANGE_MIN];
bgr[1] = VP8kClip[y + g_off - YUV_RANGE_MIN];
bgr[2] = VP8kClip[y + r_off - YUV_RANGE_MIN];
}
static WEBP_INLINE void VP8YuvToRgb565(uint8_t y, uint8_t u, uint8_t v, static WEBP_INLINE void VP8YuvToRgb565(uint8_t y, uint8_t u, uint8_t v,
uint8_t* const rgb) { uint8_t* const rgb) {
const int r_off = VP8kVToR[v]; const int r_off = VP8kVToR[v];
@ -87,12 +106,6 @@ static WEBP_INLINE void VP8YuvToRgb565(uint8_t y, uint8_t u, uint8_t v,
#endif #endif
} }
static WEBP_INLINE void VP8YuvToArgb(uint8_t y, uint8_t u, uint8_t v,
uint8_t* const argb) {
argb[0] = 0xff;
VP8YuvToRgb(y, u, v, argb + 1);
}
static WEBP_INLINE void VP8YuvToRgba4444(uint8_t y, uint8_t u, uint8_t v, static WEBP_INLINE void VP8YuvToRgba4444(uint8_t y, uint8_t u, uint8_t v,
uint8_t* const argb) { uint8_t* const argb) {
const int r_off = VP8kVToR[v]; const int r_off = VP8kVToR[v];
@ -110,14 +123,92 @@ static WEBP_INLINE void VP8YuvToRgba4444(uint8_t y, uint8_t u, uint8_t v,
#endif #endif
} }
#else // Table-free version (slower on x86)
// These constants are 16b fixed-point version of ITU-R BT.601 constants
#define kYScale 76309 // 1.164 = 255 / 219
#define kVToR 104597 // 1.596 = 255 / 112 * 0.701
#define kUToG 25674 // 0.391 = 255 / 112 * 0.886 * 0.114 / 0.587
#define kVToG 53278 // 0.813 = 255 / 112 * 0.701 * 0.299 / 0.587
#define kUToB 132201 // 2.018 = 255 / 112 * 0.886
#define kRCst (-kYScale * 16 - kVToR * 128 + YUV_HALF)
#define kGCst (-kYScale * 16 + kUToG * 128 + kVToG * 128 + YUV_HALF)
#define kBCst (-kYScale * 16 - kUToB * 128 + YUV_HALF)
static WEBP_INLINE uint8_t VP8Clip8(int v) {
return ((v & ~YUV_MASK) == 0) ? (uint8_t)(v >> YUV_FIX)
: (v < 0) ? 0u : 255u;
}
static WEBP_INLINE uint8_t VP8ClipN(int v, int N) { // clip to N bits
return ((v & ~YUV_MASK) == 0) ? (uint8_t)(v >> (YUV_FIX + (8 - N)))
: (v < 0) ? 0u : (255u >> (8 - N));
}
static WEBP_INLINE int VP8YUVToR(int y, int v) {
return kYScale * y + kVToR * v + kRCst;
}
static WEBP_INLINE int VP8YUVToG(int y, int u, int v) {
return kYScale * y - kUToG * u - kVToG * v + kGCst;
}
static WEBP_INLINE int VP8YUVToB(int y, int u) {
return kYScale * y + kUToB * u + kBCst;
}
static WEBP_INLINE void VP8YuvToRgb(uint8_t y, uint8_t u, uint8_t v,
uint8_t* const rgb) {
rgb[0] = VP8Clip8(VP8YUVToR(y, v));
rgb[1] = VP8Clip8(VP8YUVToG(y, u, v));
rgb[2] = VP8Clip8(VP8YUVToB(y, u));
}
static WEBP_INLINE void VP8YuvToBgr(uint8_t y, uint8_t u, uint8_t v, static WEBP_INLINE void VP8YuvToBgr(uint8_t y, uint8_t u, uint8_t v,
uint8_t* const bgr) { uint8_t* const bgr) {
const int r_off = VP8kVToR[v]; bgr[0] = VP8Clip8(VP8YUVToB(y, u));
const int g_off = (VP8kVToG[v] + VP8kUToG[u]) >> YUV_FIX; bgr[1] = VP8Clip8(VP8YUVToG(y, u, v));
const int b_off = VP8kUToB[u]; bgr[2] = VP8Clip8(VP8YUVToR(y, v));
bgr[0] = VP8kClip[y + b_off - YUV_RANGE_MIN]; }
bgr[1] = VP8kClip[y + g_off - YUV_RANGE_MIN];
bgr[2] = VP8kClip[y + r_off - YUV_RANGE_MIN]; static WEBP_INLINE void VP8YuvToRgb565(uint8_t y, uint8_t u, uint8_t v,
uint8_t* const rgb) {
const int r = VP8Clip8(VP8YUVToR(y, u));
const int g = VP8ClipN(VP8YUVToG(y, u, v), 6);
const int b = VP8ClipN(VP8YUVToB(y, v), 5);
const uint8_t rg = (r & 0xf8) | (g >> 3);
const uint8_t gb = (g << 5) | b;
#ifdef WEBP_SWAP_16BIT_CSP
rgb[0] = gb;
rgb[1] = rg;
#else
rgb[0] = rg;
rgb[1] = gb;
#endif
}
static WEBP_INLINE void VP8YuvToRgba4444(uint8_t y, uint8_t u, uint8_t v,
uint8_t* const argb) {
const int r = VP8Clip8(VP8YUVToR(y, u));
const int g = VP8ClipN(VP8YUVToG(y, u, v), 4);
const int b = VP8Clip8(VP8YUVToB(y, v));
const uint8_t rg = (r & 0xf0) | g;
const uint8_t ba = b | 0x0f; // overwrite the lower 4 bits
#ifdef WEBP_SWAP_16BIT_CSP
argb[0] = ba;
argb[1] = rg;
#else
argb[0] = rg;
argb[1] = ba;
#endif
}
#endif // WEBP_YUV_USE_TABLE
static WEBP_INLINE void VP8YuvToArgb(uint8_t y, uint8_t u, uint8_t v,
uint8_t* const argb) {
argb[0] = 0xff;
VP8YuvToRgb(y, u, v, argb + 1);
} }
static WEBP_INLINE void VP8YuvToBgra(uint8_t y, uint8_t u, uint8_t v, static WEBP_INLINE void VP8YuvToBgra(uint8_t y, uint8_t u, uint8_t v,