mirror of
https://github.com/webmproject/libwebp.git
synced 2024-11-20 04:18:26 +01:00
d3006f4b96
- Remove SHALF constant so that we get back the original value when calling UpScale then downscale with rounding - Make the linear->gamma precomputed table bigger (8 bits rather than 5) - Round values in kLinearToGammaTabS Change-Id: Ic9634d32cf93de321d2f6e9e4cad7f156d8d07df
464 lines
16 KiB
C
464 lines
16 KiB
C
// Copyright 2022 Google Inc. All Rights Reserved.
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//
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// Use of this source code is governed by a BSD-style license
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// that can be found in the COPYING file in the root of the source
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// tree. An additional intellectual property rights grant can be found
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// in the file PATENTS. All contributing project authors may
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// be found in the AUTHORS file in the root of the source tree.
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// -----------------------------------------------------------------------------
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//
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// Sharp RGB to YUV conversion.
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//
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// Author: Skal (pascal.massimino@gmail.com)
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#include "sharpyuv/sharpyuv.h"
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#include <assert.h>
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#include <stdlib.h>
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#include <math.h>
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#include <string.h>
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#include "src/webp/types.h"
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#include "src/dsp/cpu.h"
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#include "sharpyuv/sharpyuv_dsp.h"
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//------------------------------------------------------------------------------
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// Sharp RGB->YUV conversion
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static const int kNumIterations = 4;
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static const int kMinDimensionIterativeConversion = 4;
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#define YUV_FIX 16 // fixed-point precision for RGB->YUV
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static const int kYuvHalf = 1 << (YUV_FIX - 1);
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// We could use SFIX=0 and only uint8_t for fixed_y_t, but it produces some
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// banding sometimes. Better use extra precision.
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#define SFIX 2 // fixed-point precision of RGB and Y/W
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#define MAX_Y_T ((256 << SFIX) - 1)
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typedef int16_t fixed_t; // signed type with extra SFIX precision for UV
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typedef uint16_t fixed_y_t; // unsigned type with extra SFIX precision for W
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static const int kYuvRounder = (1 << (YUV_FIX + SFIX - 1));
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//------------------------------------------------------------------------------
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// Code for gamma correction
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// Gamma correction compensates loss of resolution during chroma subsampling.
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static const double kGammaF = 1./0.45;
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#define GAMMA_TAB_FIX 8
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#define GAMMA_TAB_SIZE (1 << GAMMA_TAB_FIX)
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static uint32_t kLinearToGammaTabS[GAMMA_TAB_SIZE + 2];
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#define GAMMA_TO_LINEAR_BITS 14
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static const int kGammaToLinearHalf = 1 << (GAMMA_TO_LINEAR_BITS - 1);
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static uint32_t kGammaToLinearTabS[MAX_Y_T + 1]; // size scales with Y_FIX
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static volatile int kGammaTablesSOk = 0;
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static void InitGammaTablesS(void) {
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assert(2 * GAMMA_TO_LINEAR_BITS < 32); // we use uint32_t intermediate values
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if (!kGammaTablesSOk) {
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int v;
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const double norm = 1. / MAX_Y_T;
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const double scale = 1. / GAMMA_TAB_SIZE;
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const double a = 0.09929682680944;
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const double thresh = 0.018053968510807;
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const double final_scale = 1 << GAMMA_TO_LINEAR_BITS;
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for (v = 0; v <= MAX_Y_T; ++v) {
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const double g = norm * v;
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double value;
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if (g <= thresh * 4.5) {
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value = g / 4.5;
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} else {
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const double a_rec = 1. / (1. + a);
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value = pow(a_rec * (g + a), kGammaF);
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}
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kGammaToLinearTabS[v] = (uint32_t)(value * final_scale + .5);
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}
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for (v = 0; v <= GAMMA_TAB_SIZE; ++v) {
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const double g = scale * v;
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double value;
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if (g <= thresh) {
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value = 4.5 * g;
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} else {
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value = (1. + a) * pow(g, 1. / kGammaF) - a;
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}
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kLinearToGammaTabS[v] = (uint32_t)(MAX_Y_T * value + 0.5);
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}
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// to prevent small rounding errors to cause read-overflow:
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kLinearToGammaTabS[GAMMA_TAB_SIZE + 1] = kLinearToGammaTabS[GAMMA_TAB_SIZE];
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kGammaTablesSOk = 1;
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}
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}
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// return value has a fixed-point precision of GAMMA_TO_LINEAR_BITS
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static WEBP_INLINE uint32_t GammaToLinearS(int v) {
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return kGammaToLinearTabS[v];
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}
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static WEBP_INLINE uint32_t LinearToGammaS(uint32_t value) {
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// 'value' is in GAMMA_TO_LINEAR_BITS fractional precision
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const uint32_t v = value * GAMMA_TAB_SIZE;
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const uint32_t tab_pos = v >> GAMMA_TO_LINEAR_BITS;
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// fractional part, in GAMMA_TO_LINEAR_BITS fixed-point precision
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const uint32_t x = v - (tab_pos << GAMMA_TO_LINEAR_BITS); // fractional part
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// v0 / v1 are in GAMMA_TO_LINEAR_BITS fixed-point precision (range [0..1])
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const uint32_t v0 = kLinearToGammaTabS[tab_pos + 0];
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const uint32_t v1 = kLinearToGammaTabS[tab_pos + 1];
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// Final interpolation.
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const uint32_t v2 = (v1 - v0) * x; // note: v1 >= v0.
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const uint32_t result =
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v0 + ((v2 + kGammaToLinearHalf) >> GAMMA_TO_LINEAR_BITS);
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return result;
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}
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//------------------------------------------------------------------------------
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static uint8_t clip_8b(fixed_t v) {
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return (!(v & ~0xff)) ? (uint8_t)v : (v < 0) ? 0u : 255u;
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}
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static fixed_y_t clip_y(int y) {
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return (!(y & ~MAX_Y_T)) ? (fixed_y_t)y : (y < 0) ? 0 : MAX_Y_T;
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}
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//------------------------------------------------------------------------------
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static int RGBToGray(int r, int g, int b) {
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const int luma = 13933 * r + 46871 * g + 4732 * b + kYuvHalf;
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return (luma >> YUV_FIX);
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}
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static uint32_t ScaleDown(int a, int b, int c, int d) {
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const uint32_t A = GammaToLinearS(a);
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const uint32_t B = GammaToLinearS(b);
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const uint32_t C = GammaToLinearS(c);
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const uint32_t D = GammaToLinearS(d);
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return LinearToGammaS((A + B + C + D + 2) >> 2);
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}
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static WEBP_INLINE void UpdateW(const fixed_y_t* src, fixed_y_t* dst, int w) {
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int i;
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for (i = 0; i < w; ++i) {
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const uint32_t R = GammaToLinearS(src[0 * w + i]);
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const uint32_t G = GammaToLinearS(src[1 * w + i]);
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const uint32_t B = GammaToLinearS(src[2 * w + i]);
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const uint32_t Y = RGBToGray(R, G, B);
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dst[i] = (fixed_y_t)LinearToGammaS(Y);
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}
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}
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static void UpdateChroma(const fixed_y_t* src1, const fixed_y_t* src2,
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fixed_t* dst, int uv_w) {
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int i;
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for (i = 0; i < uv_w; ++i) {
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const int r = ScaleDown(src1[0 * uv_w + 0], src1[0 * uv_w + 1],
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src2[0 * uv_w + 0], src2[0 * uv_w + 1]);
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const int g = ScaleDown(src1[2 * uv_w + 0], src1[2 * uv_w + 1],
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src2[2 * uv_w + 0], src2[2 * uv_w + 1]);
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const int b = ScaleDown(src1[4 * uv_w + 0], src1[4 * uv_w + 1],
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src2[4 * uv_w + 0], src2[4 * uv_w + 1]);
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const int W = RGBToGray(r, g, b);
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dst[0 * uv_w] = (fixed_t)(r - W);
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dst[1 * uv_w] = (fixed_t)(g - W);
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dst[2 * uv_w] = (fixed_t)(b - W);
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dst += 1;
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src1 += 2;
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src2 += 2;
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}
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}
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static void StoreGray(const fixed_y_t* rgb, fixed_y_t* y, int w) {
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int i;
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assert(w > 0);
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for (i = 0; i < w; ++i) {
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y[i] = RGBToGray(rgb[0 * w + i], rgb[1 * w + i], rgb[2 * w + i]);
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}
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}
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//------------------------------------------------------------------------------
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static WEBP_INLINE fixed_y_t Filter2(int A, int B, int W0) {
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const int v0 = (A * 3 + B + 2) >> 2;
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return clip_y(v0 + W0);
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}
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//------------------------------------------------------------------------------
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static WEBP_INLINE fixed_y_t UpLift(uint8_t a) { // 8bit -> SFIX
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return ((fixed_y_t)a << SFIX);
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}
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static void ImportOneRow(const uint8_t* const r_ptr,
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const uint8_t* const g_ptr,
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const uint8_t* const b_ptr,
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int step,
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int pic_width,
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fixed_y_t* const dst) {
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int i;
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const int w = (pic_width + 1) & ~1;
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for (i = 0; i < pic_width; ++i) {
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const int off = i * step;
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dst[i + 0 * w] = UpLift(r_ptr[off]);
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dst[i + 1 * w] = UpLift(g_ptr[off]);
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dst[i + 2 * w] = UpLift(b_ptr[off]);
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}
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if (pic_width & 1) { // replicate rightmost pixel
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dst[pic_width + 0 * w] = dst[pic_width + 0 * w - 1];
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dst[pic_width + 1 * w] = dst[pic_width + 1 * w - 1];
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dst[pic_width + 2 * w] = dst[pic_width + 2 * w - 1];
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}
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}
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static void InterpolateTwoRows(const fixed_y_t* const best_y,
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const fixed_t* prev_uv,
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const fixed_t* cur_uv,
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const fixed_t* next_uv,
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int w,
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fixed_y_t* out1,
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fixed_y_t* out2) {
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const int uv_w = w >> 1;
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const int len = (w - 1) >> 1; // length to filter
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int k = 3;
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while (k-- > 0) { // process each R/G/B segments in turn
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// special boundary case for i==0
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out1[0] = Filter2(cur_uv[0], prev_uv[0], best_y[0]);
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out2[0] = Filter2(cur_uv[0], next_uv[0], best_y[w]);
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SharpYuvFilterRow(cur_uv, prev_uv, len, best_y + 0 + 1, out1 + 1);
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SharpYuvFilterRow(cur_uv, next_uv, len, best_y + w + 1, out2 + 1);
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// special boundary case for i == w - 1 when w is even
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if (!(w & 1)) {
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out1[w - 1] = Filter2(cur_uv[uv_w - 1], prev_uv[uv_w - 1],
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best_y[w - 1 + 0]);
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out2[w - 1] = Filter2(cur_uv[uv_w - 1], next_uv[uv_w - 1],
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best_y[w - 1 + w]);
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}
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out1 += w;
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out2 += w;
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prev_uv += uv_w;
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cur_uv += uv_w;
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next_uv += uv_w;
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}
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}
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static WEBP_INLINE uint8_t RGBToYUVComponent(int r, int g, int b,
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const int coeffs[4]) {
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const int luma = coeffs[0] * r + coeffs[1] * g + coeffs[2] * b +
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(coeffs[3] << SFIX) + kYuvRounder;
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return clip_8b((luma >> (YUV_FIX + SFIX)));
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}
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static int ConvertWRGBToYUV(const fixed_y_t* best_y, const fixed_t* best_uv,
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uint8_t* dst_y, int dst_stride_y, uint8_t* dst_u,
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int dst_stride_u, uint8_t* dst_v, int dst_stride_v,
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int width, int height,
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const SharpYuvConversionMatrix* yuv_matrix) {
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int i, j;
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const fixed_t* const best_uv_base = best_uv;
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const int w = (width + 1) & ~1;
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const int h = (height + 1) & ~1;
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const int uv_w = w >> 1;
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const int uv_h = h >> 1;
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for (best_uv = best_uv_base, j = 0; j < height; ++j) {
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for (i = 0; i < width; ++i) {
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const int off = (i >> 1);
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const int W = best_y[i];
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const int r = best_uv[off + 0 * uv_w] + W;
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const int g = best_uv[off + 1 * uv_w] + W;
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const int b = best_uv[off + 2 * uv_w] + W;
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dst_y[i] = RGBToYUVComponent(r, g, b, yuv_matrix->rgb_to_y);
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}
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best_y += w;
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best_uv += (j & 1) * 3 * uv_w;
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dst_y += dst_stride_y;
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}
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for (best_uv = best_uv_base, j = 0; j < uv_h; ++j) {
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for (i = 0; i < uv_w; ++i) {
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const int off = i;
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const int r = best_uv[off + 0 * uv_w];
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const int g = best_uv[off + 1 * uv_w];
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const int b = best_uv[off + 2 * uv_w];
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dst_u[i] = RGBToYUVComponent(r, g, b, yuv_matrix->rgb_to_u);
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dst_v[i] = RGBToYUVComponent(r, g, b, yuv_matrix->rgb_to_v);
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}
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best_uv += 3 * uv_w;
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dst_u += dst_stride_u;
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dst_v += dst_stride_v;
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}
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return 1;
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}
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//------------------------------------------------------------------------------
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// Main function
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static void* SafeMalloc(uint64_t nmemb, size_t size) {
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const uint64_t total_size = nmemb * (uint64_t)size;
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if (total_size != (size_t)total_size) return NULL;
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return malloc((size_t)total_size);
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}
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#define SAFE_ALLOC(W, H, T) ((T*)SafeMalloc((W) * (H), sizeof(T)))
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static int DoSharpArgbToYuv(const uint8_t* r_ptr, const uint8_t* g_ptr,
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const uint8_t* b_ptr, int step, int rgb_stride,
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uint8_t* dst_y, int dst_stride_y, uint8_t* dst_u,
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int dst_stride_u, uint8_t* dst_v, int dst_stride_v,
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int width, int height,
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const SharpYuvConversionMatrix* yuv_matrix) {
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// we expand the right/bottom border if needed
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const int w = (width + 1) & ~1;
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const int h = (height + 1) & ~1;
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const int uv_w = w >> 1;
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const int uv_h = h >> 1;
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uint64_t prev_diff_y_sum = ~0;
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int j, iter;
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// TODO(skal): allocate one big memory chunk. But for now, it's easier
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// for valgrind debugging to have several chunks.
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fixed_y_t* const tmp_buffer = SAFE_ALLOC(w * 3, 2, fixed_y_t); // scratch
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fixed_y_t* const best_y_base = SAFE_ALLOC(w, h, fixed_y_t);
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fixed_y_t* const target_y_base = SAFE_ALLOC(w, h, fixed_y_t);
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fixed_y_t* const best_rgb_y = SAFE_ALLOC(w, 2, fixed_y_t);
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fixed_t* const best_uv_base = SAFE_ALLOC(uv_w * 3, uv_h, fixed_t);
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fixed_t* const target_uv_base = SAFE_ALLOC(uv_w * 3, uv_h, fixed_t);
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fixed_t* const best_rgb_uv = SAFE_ALLOC(uv_w * 3, 1, fixed_t);
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fixed_y_t* best_y = best_y_base;
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fixed_y_t* target_y = target_y_base;
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fixed_t* best_uv = best_uv_base;
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fixed_t* target_uv = target_uv_base;
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const uint64_t diff_y_threshold = (uint64_t)(3.0 * w * h);
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int ok;
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if (best_y_base == NULL || best_uv_base == NULL ||
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target_y_base == NULL || target_uv_base == NULL ||
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best_rgb_y == NULL || best_rgb_uv == NULL ||
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tmp_buffer == NULL) {
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ok = 0;
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goto End;
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}
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// Import RGB samples to W/RGB representation.
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for (j = 0; j < height; j += 2) {
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const int is_last_row = (j == height - 1);
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fixed_y_t* const src1 = tmp_buffer + 0 * w;
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fixed_y_t* const src2 = tmp_buffer + 3 * w;
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// prepare two rows of input
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ImportOneRow(r_ptr, g_ptr, b_ptr, step, width, src1);
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if (!is_last_row) {
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ImportOneRow(r_ptr + rgb_stride, g_ptr + rgb_stride, b_ptr + rgb_stride,
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step, width, src2);
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} else {
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memcpy(src2, src1, 3 * w * sizeof(*src2));
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}
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StoreGray(src1, best_y + 0, w);
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StoreGray(src2, best_y + w, w);
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UpdateW(src1, target_y, w);
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UpdateW(src2, target_y + w, w);
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UpdateChroma(src1, src2, target_uv, uv_w);
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memcpy(best_uv, target_uv, 3 * uv_w * sizeof(*best_uv));
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best_y += 2 * w;
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best_uv += 3 * uv_w;
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target_y += 2 * w;
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target_uv += 3 * uv_w;
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r_ptr += 2 * rgb_stride;
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g_ptr += 2 * rgb_stride;
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b_ptr += 2 * rgb_stride;
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}
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// Iterate and resolve clipping conflicts.
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for (iter = 0; iter < kNumIterations; ++iter) {
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const fixed_t* cur_uv = best_uv_base;
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const fixed_t* prev_uv = best_uv_base;
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uint64_t diff_y_sum = 0;
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best_y = best_y_base;
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best_uv = best_uv_base;
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target_y = target_y_base;
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target_uv = target_uv_base;
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for (j = 0; j < h; j += 2) {
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fixed_y_t* const src1 = tmp_buffer + 0 * w;
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fixed_y_t* const src2 = tmp_buffer + 3 * w;
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{
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const fixed_t* const next_uv = cur_uv + ((j < h - 2) ? 3 * uv_w : 0);
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InterpolateTwoRows(best_y, prev_uv, cur_uv, next_uv, w, src1, src2);
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prev_uv = cur_uv;
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cur_uv = next_uv;
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}
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UpdateW(src1, best_rgb_y + 0 * w, w);
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UpdateW(src2, best_rgb_y + 1 * w, w);
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UpdateChroma(src1, src2, best_rgb_uv, uv_w);
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// update two rows of Y and one row of RGB
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diff_y_sum += SharpYuvUpdateY(target_y, best_rgb_y, best_y, 2 * w);
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SharpYuvUpdateRGB(target_uv, best_rgb_uv, best_uv, 3 * uv_w);
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best_y += 2 * w;
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best_uv += 3 * uv_w;
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target_y += 2 * w;
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target_uv += 3 * uv_w;
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}
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// test exit condition
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if (iter > 0) {
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if (diff_y_sum < diff_y_threshold) break;
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if (diff_y_sum > prev_diff_y_sum) break;
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}
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prev_diff_y_sum = diff_y_sum;
|
|
}
|
|
// final reconstruction
|
|
ok = ConvertWRGBToYUV(best_y_base, best_uv_base, dst_y, dst_stride_y, dst_u,
|
|
dst_stride_u, dst_v, dst_stride_v, width, height,
|
|
yuv_matrix);
|
|
|
|
End:
|
|
free(best_y_base);
|
|
free(best_uv_base);
|
|
free(target_y_base);
|
|
free(target_uv_base);
|
|
free(best_rgb_y);
|
|
free(best_rgb_uv);
|
|
free(tmp_buffer);
|
|
return ok;
|
|
}
|
|
#undef SAFE_ALLOC
|
|
|
|
// Hidden exported init function.
|
|
// By default SharpYuvConvert calls it with NULL. If needed, users can declare
|
|
// it as extern and call it with a VP8CPUInfo function.
|
|
extern void SharpYuvInit(VP8CPUInfo cpu_info_func);
|
|
void SharpYuvInit(VP8CPUInfo cpu_info_func) {
|
|
static volatile VP8CPUInfo sharpyuv_last_cpuinfo_used =
|
|
(VP8CPUInfo)&sharpyuv_last_cpuinfo_used;
|
|
const int initialized =
|
|
(sharpyuv_last_cpuinfo_used != (VP8CPUInfo)&sharpyuv_last_cpuinfo_used);
|
|
if (cpu_info_func == NULL && initialized) return;
|
|
if (sharpyuv_last_cpuinfo_used == cpu_info_func) return;
|
|
|
|
SharpYuvInitDsp(cpu_info_func);
|
|
if (!initialized) {
|
|
InitGammaTablesS();
|
|
}
|
|
|
|
sharpyuv_last_cpuinfo_used = cpu_info_func;
|
|
}
|
|
|
|
int SharpYuvConvert(const uint8_t* r_ptr, const uint8_t* g_ptr,
|
|
const uint8_t* b_ptr, int step, int rgb_stride,
|
|
uint8_t* dst_y, int dst_stride_y, uint8_t* dst_u,
|
|
int dst_stride_u, uint8_t* dst_v, int dst_stride_v,
|
|
int width, int height,
|
|
const SharpYuvConversionMatrix* yuv_matrix) {
|
|
if (width < kMinDimensionIterativeConversion ||
|
|
height < kMinDimensionIterativeConversion) {
|
|
return 0;
|
|
}
|
|
SharpYuvInit(NULL);
|
|
return DoSharpArgbToYuv(r_ptr, g_ptr, b_ptr, step, rgb_stride, dst_y,
|
|
dst_stride_y, dst_u, dst_stride_u, dst_v,
|
|
dst_stride_v, width, height, yuv_matrix);
|
|
}
|
|
|
|
//------------------------------------------------------------------------------
|