// Copyright 2014 Google Inc. All Rights Reserved.
//
// Use of this source code is governed by a BSD-style license
// that can be found in the COPYING file in the root of the source
// tree. An additional intellectual property rights grant can be found
// in the file PATENTS. All contributing project authors may
// be found in the AUTHORS file in the root of the source tree.
// -----------------------------------------------------------------------------
//
// WebPPicture utils for colorspace conversion
//
// Author: Skal (pascal.massimino@gmail.com)
#include <assert.h>
#include <stdlib.h>
#include <math.h>
#include "./vp8enci.h"
#include "../utils/random.h"
#include "../dsp/yuv.h"
// Uncomment to disable gamma-compression during RGB->U/V averaging
#define USE_GAMMA_COMPRESSION
static const union {
uint32_t argb;
uint8_t bytes[4];
} test_endian = { 0xff000000u };
#define ALPHA_IS_LAST (test_endian.bytes[3] == 0xff)
static WEBP_INLINE uint32_t MakeARGB32(int a, int r, int g, int b) {
return (((uint32_t)a << 24) | (r << 16) | (g << 8) | b);
}
//------------------------------------------------------------------------------
// Detection of non-trivial transparency
// Returns true if alpha[] has non-0xff values.
static int CheckNonOpaque(const uint8_t* alpha, int width, int height,
int x_step, int y_step) {
if (alpha == NULL) return 0;
while (height-- > 0) {
int x;
for (x = 0; x < width * x_step; x += x_step) {
if (alpha[x] != 0xff) return 1; // TODO(skal): check 4/8 bytes at a time.
}
alpha += y_step;
}
return 0;
}
// Checking for the presence of non-opaque alpha.
int WebPPictureHasTransparency(const WebPPicture* picture) {
if (picture == NULL) return 0;
if (!picture->use_argb) {
return CheckNonOpaque(picture->a, picture->width, picture->height,
1, picture->a_stride);
} else {
int x, y;
const uint32_t* argb = picture->argb;
if (argb == NULL) return 0;
for (y = 0; y < picture->height; ++y) {
for (x = 0; x < picture->width; ++x) {
if (argb[x] < 0xff000000u) return 1; // test any alpha values != 0xff
}
argb += picture->argb_stride;
}
}
return 0;
}
//------------------------------------------------------------------------------
// RGB -> YUV conversion
static int RGBToY(int r, int g, int b, VP8Random* const rg) {
return VP8RGBToY(r, g, b, VP8RandomBits(rg, YUV_FIX));
}
static int RGBToU(int r, int g, int b, VP8Random* const rg) {
return VP8RGBToU(r, g, b, VP8RandomBits(rg, YUV_FIX + 2));
}
static int RGBToV(int r, int g, int b, VP8Random* const rg) {
return VP8RGBToV(r, g, b, VP8RandomBits(rg, YUV_FIX + 2));
}
//------------------------------------------------------------------------------
#if defined(USE_GAMMA_COMPRESSION)
// gamma-compensates loss of resolution during chroma subsampling
#define kGamma 0.80
#define kGammaFix 12 // fixed-point precision for linear values
#define kGammaScale ((1 << kGammaFix) - 1)
#define kGammaTabFix 7 // fixed-point fractional bits precision
#define kGammaTabScale (1 << kGammaTabFix)
#define kGammaTabRounder (kGammaTabScale >> 1)
#define kGammaTabSize (1 << (kGammaFix - kGammaTabFix))
static int kLinearToGammaTab[kGammaTabSize + 1];
static uint16_t kGammaToLinearTab[256];
static int kGammaTablesOk = 0;
static void InitGammaTables(void) {
if (!kGammaTablesOk) {
int v;
const double scale = 1. / kGammaScale;
for (v = 0; v <= 255; ++v) {
kGammaToLinearTab[v] =
(uint16_t)(pow(v / 255., kGamma) * kGammaScale + .5);
}
for (v = 0; v <= kGammaTabSize; ++v) {
const double x = scale * (v << kGammaTabFix);
kLinearToGammaTab[v] = (int)(pow(x, 1. / kGamma) * 255. + .5);
}
kGammaTablesOk = 1;
}
}
static WEBP_INLINE uint32_t GammaToLinear(uint8_t v) {
return kGammaToLinearTab[v];
}
// Convert a linear value 'v' to YUV_FIX+2 fixed-point precision
// U/V value, suitable for RGBToU/V calls.
static WEBP_INLINE int LinearToGamma(uint32_t base_value, int shift) {
const int v = base_value << shift; // final uplifted value
const int tab_pos = v >> (kGammaTabFix + 2); // integer part
const int x = v & ((kGammaTabScale << 2) - 1); // fractional part
const int v0 = kLinearToGammaTab[tab_pos];
const int v1 = kLinearToGammaTab[tab_pos + 1];
const int y = v1 * x + v0 * ((kGammaTabScale << 2) - x); // interpolate
return (y + kGammaTabRounder) >> kGammaTabFix; // descale
}
#else
static void InitGammaTables(void) {}
static WEBP_INLINE uint32_t GammaToLinear(uint8_t v) { return v; }
static WEBP_INLINE int LinearToGamma(uint32_t base_value, int shift) {
return (int)(base_value << shift);
}
#endif // USE_GAMMA_COMPRESSION
//------------------------------------------------------------------------------
#define SUM4(ptr) LinearToGamma( \
GammaToLinear((ptr)[0]) + \
GammaToLinear((ptr)[step]) + \
GammaToLinear((ptr)[rgb_stride]) + \
GammaToLinear((ptr)[rgb_stride + step]), 0) \
#define SUM2H(ptr) \
LinearToGamma(GammaToLinear((ptr)[0]) + GammaToLinear((ptr)[step]), 1)
#define SUM2V(ptr) \
LinearToGamma(GammaToLinear((ptr)[0]) + GammaToLinear((ptr)[rgb_stride]), 1)
#define SUM1(ptr) \
LinearToGamma(GammaToLinear((ptr)[0]), 2)
#define RGB_TO_UV(x, y, SUM) { \
const int src = (2 * (step * (x) + (y) * rgb_stride)); \
const int dst = (x) + (y) * picture->uv_stride; \
const int r = SUM(r_ptr + src); \
const int g = SUM(g_ptr + src); \
const int b = SUM(b_ptr + src); \
picture->u[dst] = RGBToU(r, g, b, &rg); \
picture->v[dst] = RGBToV(r, g, b, &rg); \
}
static int ImportYUVAFromRGBA(const uint8_t* const r_ptr,
const uint8_t* const g_ptr,
const uint8_t* const b_ptr,
const uint8_t* const a_ptr,
int step, // bytes per pixel
int rgb_stride, // bytes per scanline
float dithering,
WebPPicture* const picture) {
int x, y;
const int width = picture->width;
const int height = picture->height;
const int has_alpha = CheckNonOpaque(a_ptr, width, height, step, rgb_stride);
VP8Random rg;
if (has_alpha) {
picture->colorspace |= WEBP_CSP_ALPHA_BIT;
} else {
picture->colorspace &= WEBP_CSP_UV_MASK;
}
picture->use_argb = 0;
if (!WebPPictureAllocYUVA(picture, width, height)) return 0;
VP8InitRandom(&rg, dithering);
InitGammaTables();
// Import luma plane
for (y = 0; y < height; ++y) {
uint8_t* const dst = &picture->y[y * picture->y_stride];
for (x = 0; x < width; ++x) {
const int offset = step * x + y * rgb_stride;
dst[x] = RGBToY(r_ptr[offset], g_ptr[offset], b_ptr[offset], &rg);
}
}
// Downsample U/V plane
for (y = 0; y < (height >> 1); ++y) {
for (x = 0; x < (width >> 1); ++x) {
RGB_TO_UV(x, y, SUM4);
}
if (width & 1) {
RGB_TO_UV(x, y, SUM2V);
}
}
if (height & 1) {
for (x = 0; x < (width >> 1); ++x) {
RGB_TO_UV(x, y, SUM2H);
}
if (width & 1) {
RGB_TO_UV(x, y, SUM1);
}
}
if (has_alpha) {
assert(step >= 4);
assert(picture->a != NULL);
for (y = 0; y < height; ++y) {
for (x = 0; x < width; ++x) {
picture->a[x + y * picture->a_stride] =
a_ptr[step * x + y * rgb_stride];
}
}
}
return 1;
}
#undef SUM4
#undef SUM2V
#undef SUM2H
#undef SUM1
#undef RGB_TO_UV
//------------------------------------------------------------------------------
// call for ARGB->YUVA conversion
int WebPPictureARGBToYUVADithered(WebPPicture* picture, WebPEncCSP colorspace,
float dithering) {
if (picture == NULL) return 0;
if (picture->argb == NULL) {
return WebPEncodingSetError(picture, VP8_ENC_ERROR_NULL_PARAMETER);
} else {
const uint8_t* const argb = (const uint8_t*)picture->argb;
const uint8_t* const r = ALPHA_IS_LAST ? argb + 2 : argb + 1;
const uint8_t* const g = ALPHA_IS_LAST ? argb + 1 : argb + 2;
const uint8_t* const b = ALPHA_IS_LAST ? argb + 0 : argb + 3;
const uint8_t* const a = ALPHA_IS_LAST ? argb + 3 : argb + 0;
picture->colorspace = colorspace;
return ImportYUVAFromRGBA(r, g, b, a, 4, 4 * picture->argb_stride,
dithering, picture);
}
}
int WebPPictureARGBToYUVA(WebPPicture* picture, WebPEncCSP colorspace) {
return WebPPictureARGBToYUVADithered(picture, colorspace, 0.f);
}
//------------------------------------------------------------------------------
// call for YUVA -> ARGB conversion
int WebPPictureYUVAToARGB(WebPPicture* picture) {
if (picture == NULL) return 0;
if (picture->y == NULL || picture->u == NULL || picture->v == NULL) {
return WebPEncodingSetError(picture, VP8_ENC_ERROR_NULL_PARAMETER);
}
if ((picture->colorspace & WEBP_CSP_ALPHA_BIT) && picture->a == NULL) {
return WebPEncodingSetError(picture, VP8_ENC_ERROR_NULL_PARAMETER);
}
if ((picture->colorspace & WEBP_CSP_UV_MASK) != WEBP_YUV420) {
return WebPEncodingSetError(picture, VP8_ENC_ERROR_INVALID_CONFIGURATION);
}
// Allocate a new argb buffer (discarding the previous one).
if (!WebPPictureAllocARGB(picture, picture->width, picture->height)) return 0;
picture->use_argb = 1;
// Convert
{
int y;
const int width = picture->width;
const int height = picture->height;
const int argb_stride = 4 * picture->argb_stride;
uint8_t* dst = (uint8_t*)picture->argb;
const uint8_t *cur_u = picture->u, *cur_v = picture->v, *cur_y = picture->y;
WebPUpsampleLinePairFunc upsample = WebPGetLinePairConverter(ALPHA_IS_LAST);
// First row, with replicated top samples.
upsample(cur_y, NULL, cur_u, cur_v, cur_u, cur_v, dst, NULL, width);
cur_y += picture->y_stride;
dst += argb_stride;
// Center rows.
for (y = 1; y + 1 < height; y += 2) {
const uint8_t* const top_u = cur_u;
const uint8_t* const top_v = cur_v;
cur_u += picture->uv_stride;
cur_v += picture->uv_stride;
upsample(cur_y, cur_y + picture->y_stride, top_u, top_v, cur_u, cur_v,
dst, dst + argb_stride, width);
cur_y += 2 * picture->y_stride;
dst += 2 * argb_stride;
}
// Last row (if needed), with replicated bottom samples.
if (height > 1 && !(height & 1)) {
upsample(cur_y, NULL, cur_u, cur_v, cur_u, cur_v, dst, NULL, width);
}
// Insert alpha values if needed, in replacement for the default 0xff ones.
if (picture->colorspace & WEBP_CSP_ALPHA_BIT) {
for (y = 0; y < height; ++y) {
uint32_t* const argb_dst = picture->argb + y * picture->argb_stride;
const uint8_t* const src = picture->a + y * picture->a_stride;
int x;
for (x = 0; x < width; ++x) {
argb_dst[x] = (argb_dst[x] & 0x00ffffffu) | ((uint32_t)src[x] << 24);
}
}
}
}
return 1;
}
//------------------------------------------------------------------------------
// automatic import / conversion
static int Import(WebPPicture* const picture,
const uint8_t* const rgb, int rgb_stride,
int step, int swap_rb, int import_alpha) {
int y;
const uint8_t* const r_ptr = rgb + (swap_rb ? 2 : 0);
const uint8_t* const g_ptr = rgb + 1;
const uint8_t* const b_ptr = rgb + (swap_rb ? 0 : 2);
const uint8_t* const a_ptr = import_alpha ? rgb + 3 : NULL;
const int width = picture->width;
const int height = picture->height;
if (!picture->use_argb) {
return ImportYUVAFromRGBA(r_ptr, g_ptr, b_ptr, a_ptr, step, rgb_stride,
0.f /* no dithering */, picture);
}
if (!WebPPictureAlloc(picture)) return 0;
assert(step >= (import_alpha ? 4 : 3));
for (y = 0; y < height; ++y) {
uint32_t* const dst = &picture->argb[y * picture->argb_stride];
int x;
for (x = 0; x < width; ++x) {
const int offset = step * x + y * rgb_stride;
dst[x] = MakeARGB32(import_alpha ? a_ptr[offset] : 0xff,
r_ptr[offset], g_ptr[offset], b_ptr[offset]);
}
}
return 1;
}
// Public API
int WebPPictureImportRGB(WebPPicture* picture,
const uint8_t* rgb, int rgb_stride) {
return (picture != NULL) ? Import(picture, rgb, rgb_stride, 3, 0, 0) : 0;
}
int WebPPictureImportBGR(WebPPicture* picture,
const uint8_t* rgb, int rgb_stride) {
return (picture != NULL) ? Import(picture, rgb, rgb_stride, 3, 1, 0) : 0;
}
int WebPPictureImportRGBA(WebPPicture* picture,
const uint8_t* rgba, int rgba_stride) {
return (picture != NULL) ? Import(picture, rgba, rgba_stride, 4, 0, 1) : 0;
}
int WebPPictureImportBGRA(WebPPicture* picture,
const uint8_t* rgba, int rgba_stride) {
return (picture != NULL) ? Import(picture, rgba, rgba_stride, 4, 1, 1) : 0;
}
int WebPPictureImportRGBX(WebPPicture* picture,
const uint8_t* rgba, int rgba_stride) {
return (picture != NULL) ? Import(picture, rgba, rgba_stride, 4, 0, 0) : 0;
}
int WebPPictureImportBGRX(WebPPicture* picture,
const uint8_t* rgba, int rgba_stride) {
return (picture != NULL) ? Import(picture, rgba, rgba_stride, 4, 1, 0) : 0;
}
//------------------------------------------------------------------------------