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76b6342ca1
snes9x/filter/xbrz.cpp
Brandon Wright 50718ac7a9 Remove unused functions in xbrz.cpp.
2018-11-17 15:19:19 -06:00

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// ****************************************************************************
// * This file is part of the xBRZ project. It is distributed under *
// * GNU General Public License: https://www.gnu.org/licenses/gpl-3.0 *
// * Copyright (C) Zenju (zenju AT gmx DOT de) - All Rights Reserved *
// * *
// * Additionally and as a special exception, the author gives permission *
// * to link the code of this program with the following libraries *
// * (or with modified versions that use the same licenses), and distribute *
// * linked combinations including the two: MAME, FreeFileSync, Snes9x *
// * You must obey the GNU General Public License in all respects for all of *
// * the code used other than MAME, FreeFileSync, Snes9x. *
// * If you modify this file, you may extend this exception to your version *
// * of the file, but you are not obligated to do so. If you do not wish to *
// * do so, delete this exception statement from your version. *
// ****************************************************************************
#include "xbrz.h"
#include <cassert>
#include <vector>
#include <algorithm>
#include <cmath> //std::sqrt
#include "xbrz_tools.h"
using namespace xbrz;
namespace
{
template <unsigned int M, unsigned int N> inline
uint32_t gradientRGB(uint32_t pixFront, uint32_t pixBack) //blend front color with opacity M / N over opaque background: http://en.wikipedia.org/wiki/Alpha_compositing#Alpha_blending
{
static_assert(0 < M && M < N && N <= 1000, "");
auto calcColor = [](unsigned char colFront, unsigned char colBack) -> unsigned char { return (colFront * M + colBack * (N - M)) / N; };
return makePixel(calcColor(getRed (pixFront), getRed (pixBack)),
calcColor(getGreen(pixFront), getGreen(pixBack)),
calcColor(getBlue (pixFront), getBlue (pixBack)));
}
template <unsigned int M, unsigned int N> inline
uint32_t gradientARGB(uint32_t pixFront, uint32_t pixBack) //find intermediate color between two colors with alpha channels (=> NO alpha blending!!!)
{
static_assert(0 < M && M < N && N <= 1000, "");
const unsigned int weightFront = getAlpha(pixFront) * M;
const unsigned int weightBack = getAlpha(pixBack) * (N - M);
const unsigned int weightSum = weightFront + weightBack;
if (weightSum == 0)
return 0;
auto calcColor = [=](unsigned char colFront, unsigned char colBack)
{
return static_cast<unsigned char>((colFront * weightFront + colBack * weightBack) / weightSum);
};
return makePixel(static_cast<unsigned char>(weightSum / N),
calcColor(getRed (pixFront), getRed (pixBack)),
calcColor(getGreen(pixFront), getGreen(pixBack)),
calcColor(getBlue (pixFront), getBlue (pixBack)));
}
//inline
//double fastSqrt(double n)
//{
// __asm //speeds up xBRZ by about 9% compared to std::sqrt which internally uses the same assembler instructions but adds some "fluff"
// {
// fld n
// fsqrt
// }
//}
//
#ifdef _MSC_VER
#define FORCE_INLINE __forceinline
#elif defined __GNUC__
#define FORCE_INLINE __attribute__((always_inline)) inline
#else
#define FORCE_INLINE inline
#endif
enum RotationDegree //clock-wise
{
ROT_0,
ROT_90,
ROT_180,
ROT_270
};
//calculate input matrix coordinates after rotation at compile time
template <RotationDegree rotDeg, size_t I, size_t J, size_t N>
struct MatrixRotation;
template <size_t I, size_t J, size_t N>
struct MatrixRotation<ROT_0, I, J, N>
{
static const size_t I_old = I;
static const size_t J_old = J;
};
template <RotationDegree rotDeg, size_t I, size_t J, size_t N> //(i, j) = (row, col) indices, N = size of (square) matrix
struct MatrixRotation
{
static const size_t I_old = N - 1 - MatrixRotation<static_cast<RotationDegree>(rotDeg - 1), I, J, N>::J_old; //old coordinates before rotation!
static const size_t J_old = MatrixRotation<static_cast<RotationDegree>(rotDeg - 1), I, J, N>::I_old; //
};
template <size_t N, RotationDegree rotDeg>
class OutputMatrix
{
public:
OutputMatrix(uint32_t* out, int outWidth) : //access matrix area, top-left at position "out" for image with given width
out_(out),
outWidth_(outWidth) {}
template <size_t I, size_t J>
uint32_t& ref() const
{
static const size_t I_old = MatrixRotation<rotDeg, I, J, N>::I_old;
static const size_t J_old = MatrixRotation<rotDeg, I, J, N>::J_old;
return *(out_ + J_old + I_old * outWidth_);
}
private:
uint32_t* out_;
const int outWidth_;
};
template <class T> inline
T square(T value) { return value * value; }
#if 0
inline
double distRGB(uint32_t pix1, uint32_t pix2)
{
const double r_diff = static_cast<int>(getRed (pix1)) - getRed (pix2);
const double g_diff = static_cast<int>(getGreen(pix1)) - getGreen(pix2);
const double b_diff = static_cast<int>(getBlue (pix1)) - getBlue (pix2);
//euklidean RGB distance
return std::sqrt(square(r_diff) + square(g_diff) + square(b_diff));
}
#endif
inline
double distYCbCr(uint32_t pix1, uint32_t pix2, double lumaWeight)
{
//http://en.wikipedia.org/wiki/YCbCr#ITU-R_BT.601_conversion
//YCbCr conversion is a matrix multiplication => take advantage of linearity by subtracting first!
const int r_diff = static_cast<int>(getRed (pix1)) - getRed (pix2); //we may delay division by 255 to after matrix multiplication
const int g_diff = static_cast<int>(getGreen(pix1)) - getGreen(pix2); //
const int b_diff = static_cast<int>(getBlue (pix1)) - getBlue (pix2); //substraction for int is noticeable faster than for double!
//const double k_b = 0.0722; //ITU-R BT.709 conversion
//const double k_r = 0.2126; //
const double k_b = 0.0593; //ITU-R BT.2020 conversion
const double k_r = 0.2627; //
const double k_g = 1 - k_b - k_r;
const double scale_b = 0.5 / (1 - k_b);
const double scale_r = 0.5 / (1 - k_r);
const double y = k_r * r_diff + k_g * g_diff + k_b * b_diff; //[!], analog YCbCr!
const double c_b = scale_b * (b_diff - y);
const double c_r = scale_r * (r_diff - y);
//we skip division by 255 to have similar range like other distance functions
return std::sqrt(square(lumaWeight * y) + square(c_b) + square(c_r));
}
inline
double distYCbCrBuffered(uint32_t pix1, uint32_t pix2)
{
//30% perf boost compared to plain distYCbCr()!
//consumes 64 MB memory; using double is only 2% faster, but takes 128 MB
static const std::vector<float> diffToDist = []
{
std::vector<float> tmp;
for (uint32_t i = 0; i < 256 * 256 * 256; ++i) //startup time: 114 ms on Intel Core i5 (four cores)
{
const int r_diff = getByte<2>(i) * 2 - 0xFF;
const int g_diff = getByte<1>(i) * 2 - 0xFF;
const int b_diff = getByte<0>(i) * 2 - 0xFF;
const double k_b = 0.0593; //ITU-R BT.2020 conversion
const double k_r = 0.2627; //
const double k_g = 1 - k_b - k_r;
const double scale_b = 0.5 / (1 - k_b);
const double scale_r = 0.5 / (1 - k_r);
const double y = k_r * r_diff + k_g * g_diff + k_b * b_diff; //[!], analog YCbCr!
const double c_b = scale_b * (b_diff - y);
const double c_r = scale_r * (r_diff - y);
tmp.push_back(static_cast<float>(std::sqrt(square(y) + square(c_b) + square(c_r))));
}
return tmp;
}();
//if (pix1 == pix2) -> 8% perf degradation!
// return 0;
//if (pix1 < pix2)
// std::swap(pix1, pix2); -> 30% perf degradation!!!
#if 1
const int r_diff = static_cast<int>(getRed (pix1)) - getRed (pix2);
const int g_diff = static_cast<int>(getGreen(pix1)) - getGreen(pix2);
const int b_diff = static_cast<int>(getBlue (pix1)) - getBlue (pix2);
return diffToDist[(((r_diff + 0xFF) / 2) << 16) | //slightly reduce precision (division by 2) to squeeze value into single byte
(((g_diff + 0xFF) / 2) << 8) |
(( b_diff + 0xFF) / 2)];
#else //not noticeably faster:
const int r_diff_tmp = ((pix1 & 0xFF0000) + 0xFF0000 - (pix2 & 0xFF0000)) / 2;
const int g_diff_tmp = ((pix1 & 0x00FF00) + 0x00FF00 - (pix2 & 0x00FF00)) / 2; //slightly reduce precision (division by 2) to squeeze value into single byte
const int b_diff_tmp = ((pix1 & 0x0000FF) + 0x0000FF - (pix2 & 0x0000FF)) / 2;
return diffToDist[(r_diff_tmp & 0xFF0000) | (g_diff_tmp & 0x00FF00) | (b_diff_tmp & 0x0000FF)];
#endif
}
enum BlendType
{
BLEND_NONE = 0,
BLEND_NORMAL, //a normal indication to blend
BLEND_DOMINANT, //a strong indication to blend
//attention: BlendType must fit into the value range of 2 bit!!!
};
struct BlendResult
{
BlendType
/**/blend_f, blend_g,
/**/blend_j, blend_k;
};
struct Kernel_4x4 //kernel for preprocessing step
{
uint32_t
/**/a, b, c, d,
/**/e, f, g, h,
/**/i, j, k, l,
/**/m, n, o, p;
};
/*
input kernel area naming convention:
-----------------
| A | B | C | D |
----|---|---|---|
| E | F | G | H | //evaluate the four corners between F, G, J, K
----|---|---|---| //input pixel is at position F
| I | J | K | L |
----|---|---|---|
| M | N | O | P |
-----------------
*/
template <class ColorDistance>
FORCE_INLINE //detect blend direction
BlendResult preProcessCorners(const Kernel_4x4& ker, const xbrz::ScalerCfg& cfg) //result: F, G, J, K corners of "GradientType"
{
BlendResult result = {};
if ((ker.f == ker.g &&
ker.j == ker.k) ||
(ker.f == ker.j &&
ker.g == ker.k))
return result;
auto dist = [&](uint32_t pix1, uint32_t pix2) { return ColorDistance::dist(pix1, pix2, cfg.luminanceWeight); };
const int weight = 4;
double jg = dist(ker.i, ker.f) + dist(ker.f, ker.c) + dist(ker.n, ker.k) + dist(ker.k, ker.h) + weight * dist(ker.j, ker.g);
double fk = dist(ker.e, ker.j) + dist(ker.j, ker.o) + dist(ker.b, ker.g) + dist(ker.g, ker.l) + weight * dist(ker.f, ker.k);
if (jg < fk) //test sample: 70% of values max(jg, fk) / min(jg, fk) are between 1.1 and 3.7 with median being 1.8
{
const bool dominantGradient = cfg.dominantDirectionThreshold * jg < fk;
if (ker.f != ker.g && ker.f != ker.j)
result.blend_f = dominantGradient ? BLEND_DOMINANT : BLEND_NORMAL;
if (ker.k != ker.j && ker.k != ker.g)
result.blend_k = dominantGradient ? BLEND_DOMINANT : BLEND_NORMAL;
}
else if (fk < jg)
{
const bool dominantGradient = cfg.dominantDirectionThreshold * fk < jg;
if (ker.j != ker.f && ker.j != ker.k)
result.blend_j = dominantGradient ? BLEND_DOMINANT : BLEND_NORMAL;
if (ker.g != ker.f && ker.g != ker.k)
result.blend_g = dominantGradient ? BLEND_DOMINANT : BLEND_NORMAL;
}
return result;
}
struct Kernel_3x3
{
uint32_t
/**/a, b, c,
/**/d, e, f,
/**/g, h, i;
};
#define DEF_GETTER(x) template <RotationDegree rotDeg> uint32_t inline get_##x(const Kernel_3x3& ker) { return ker.x; }
//we cannot and NEED NOT write "ker.##x" since ## concatenates preprocessor tokens but "." is not a token
DEF_GETTER(a) DEF_GETTER(b) DEF_GETTER(c)
DEF_GETTER(d) DEF_GETTER(e) DEF_GETTER(f)
DEF_GETTER(g) DEF_GETTER(h) DEF_GETTER(i)
#undef DEF_GETTER
#define DEF_GETTER(x, y) template <> inline uint32_t get_##x<ROT_90>(const Kernel_3x3& ker) { return ker.y; }
DEF_GETTER(b, d) DEF_GETTER(c, a)
DEF_GETTER(d, h) DEF_GETTER(e, e) DEF_GETTER(f, b)
DEF_GETTER(g, i) DEF_GETTER(h, f) DEF_GETTER(i, c)
#undef DEF_GETTER
#define DEF_GETTER(x, y) template <> inline uint32_t get_##x<ROT_180>(const Kernel_3x3& ker) { return ker.y; }
DEF_GETTER(b, h) DEF_GETTER(c, g)
DEF_GETTER(d, f) DEF_GETTER(e, e) DEF_GETTER(f, d)
DEF_GETTER(g, c) DEF_GETTER(h, b) DEF_GETTER(i, a)
#undef DEF_GETTER
#define DEF_GETTER(x, y) template <> inline uint32_t get_##x<ROT_270>(const Kernel_3x3& ker) { return ker.y; }
DEF_GETTER(b, f) DEF_GETTER(c, i)
DEF_GETTER(d, b) DEF_GETTER(e, e) DEF_GETTER(f, h)
DEF_GETTER(g, a) DEF_GETTER(h, d) DEF_GETTER(i, g)
#undef DEF_GETTER
//compress four blend types into a single byte
//inline BlendType getTopL (unsigned char b) { return static_cast<BlendType>(0x3 & b); }
inline BlendType getTopR (unsigned char b) { return static_cast<BlendType>(0x3 & (b >> 2)); }
inline BlendType getBottomR(unsigned char b) { return static_cast<BlendType>(0x3 & (b >> 4)); }
inline BlendType getBottomL(unsigned char b) { return static_cast<BlendType>(0x3 & (b >> 6)); }
inline void setTopL (unsigned char& b, BlendType bt) { b |= bt; } //buffer is assumed to be initialized before preprocessing!
inline void setTopR (unsigned char& b, BlendType bt) { b |= (bt << 2); }
inline void setBottomR(unsigned char& b, BlendType bt) { b |= (bt << 4); }
inline void setBottomL(unsigned char& b, BlendType bt) { b |= (bt << 6); }
inline bool blendingNeeded(unsigned char b) { return b != 0; }
template <RotationDegree rotDeg> inline
unsigned char rotateBlendInfo(unsigned char b) { return b; }
template <> inline unsigned char rotateBlendInfo<ROT_90 >(unsigned char b) { return ((b << 2) | (b >> 6)) & 0xff; }
template <> inline unsigned char rotateBlendInfo<ROT_180>(unsigned char b) { return ((b << 4) | (b >> 4)) & 0xff; }
template <> inline unsigned char rotateBlendInfo<ROT_270>(unsigned char b) { return ((b << 6) | (b >> 2)) & 0xff; }
#ifdef WIN32
#ifndef NDEBUG
int debugPixelX = -1;
int debugPixelY = 12;
__declspec(thread) bool breakIntoDebugger = false;
#endif
#endif
/*
input kernel area naming convention:
-------------
| A | B | C |
----|---|---|
| D | E | F | //input pixel is at position E
----|---|---|
| G | H | I |
-------------
*/
template <class Scaler, class ColorDistance, RotationDegree rotDeg>
FORCE_INLINE //perf: quite worth it!
void blendPixel(const Kernel_3x3& ker,
uint32_t* target, int trgWidth,
unsigned char blendInfo, //result of preprocessing all four corners of pixel "e"
const xbrz::ScalerCfg& cfg)
{
#define a get_a<rotDeg>(ker)
#define b get_b<rotDeg>(ker)
#define c get_c<rotDeg>(ker)
#define d get_d<rotDeg>(ker)
#define e get_e<rotDeg>(ker)
#define f get_f<rotDeg>(ker)
#define g get_g<rotDeg>(ker)
#define h get_h<rotDeg>(ker)
#define i get_i<rotDeg>(ker)
#ifdef WIN32
#ifndef NDEBUG
if (breakIntoDebugger)
__debugbreak(); //__asm int 3;
#endif
#endif
const unsigned char blend = rotateBlendInfo<rotDeg>(blendInfo);
if (getBottomR(blend) >= BLEND_NORMAL)
{
auto eq = [&](uint32_t pix1, uint32_t pix2) { return ColorDistance::dist(pix1, pix2, cfg.luminanceWeight) < cfg.equalColorTolerance; };
auto dist = [&](uint32_t pix1, uint32_t pix2) { return ColorDistance::dist(pix1, pix2, cfg.luminanceWeight); };
const bool doLineBlend = [&]() -> bool
{
if (getBottomR(blend) >= BLEND_DOMINANT)
return true;
//make sure there is no second blending in an adjacent rotation for this pixel: handles insular pixels, mario eyes
if (getTopR(blend) != BLEND_NONE && !eq(e, g)) //but support double-blending for 90 degree corners
return false;
if (getBottomL(blend) != BLEND_NONE && !eq(e, c))
return false;
//no full blending for L-shapes; blend corner only (handles "mario mushroom eyes")
if (!eq(e, i) && eq(g, h) && eq(h, i) && eq(i, f) && eq(f, c))
return false;
return true;
}();
const uint32_t px = dist(e, f) <= dist(e, h) ? f : h; //choose most similar color
OutputMatrix<Scaler::scale, rotDeg> out(target, trgWidth);
if (doLineBlend)
{
const double fg = dist(f, g); //test sample: 70% of values max(fg, hc) / min(fg, hc) are between 1.1 and 3.7 with median being 1.9
const double hc = dist(h, c); //
const bool haveShallowLine = cfg.steepDirectionThreshold * fg <= hc && e != g && d != g;
const bool haveSteepLine = cfg.steepDirectionThreshold * hc <= fg && e != c && b != c;
if (haveShallowLine)
{
if (haveSteepLine)
Scaler::blendLineSteepAndShallow(px, out);
else
Scaler::blendLineShallow(px, out);
}
else
{
if (haveSteepLine)
Scaler::blendLineSteep(px, out);
else
Scaler::blendLineDiagonal(px, out);
}
}
else
Scaler::blendCorner(px, out);
}
#undef a
#undef b
#undef c
#undef d
#undef e
#undef f
#undef g
#undef h
#undef i
}
template <class Scaler, class ColorDistance> //scaler policy: see "Scaler2x" reference implementation
void scaleImage(const uint32_t* src, uint32_t* trg, int srcWidth, int srcHeight, const xbrz::ScalerCfg& cfg, int yFirst, int yLast)
{
yFirst = std::max(yFirst, 0);
yLast = std::min(yLast, srcHeight);
if (yFirst >= yLast || srcWidth <= 0)
return;
const int trgWidth = srcWidth * Scaler::scale;
//"use" space at the end of the image as temporary buffer for "on the fly preprocessing": we even could use larger area of
//"sizeof(uint32_t) * srcWidth * (yLast - yFirst)" bytes without risk of accidental overwriting before accessing
const int bufferSize = srcWidth;
unsigned char* preProcBuffer = reinterpret_cast<unsigned char*>(trg + yLast * Scaler::scale * trgWidth) - bufferSize;
std::fill(preProcBuffer, preProcBuffer + bufferSize, '\0');
static_assert(BLEND_NONE == 0, "");
//initialize preprocessing buffer for first row of current stripe: detect upper left and right corner blending
//this cannot be optimized for adjacent processing stripes; we must not allow for a memory race condition!
if (yFirst > 0)
{
const int y = yFirst - 1;
const uint32_t* s_m1 = src + srcWidth * std::max(y - 1, 0);
const uint32_t* s_0 = src + srcWidth * y; //center line
const uint32_t* s_p1 = src + srcWidth * std::min(y + 1, srcHeight - 1);
const uint32_t* s_p2 = src + srcWidth * std::min(y + 2, srcHeight - 1);
for (int x = 0; x < srcWidth; ++x)
{
const int x_m1 = std::max(x - 1, 0);
const int x_p1 = std::min(x + 1, srcWidth - 1);
const int x_p2 = std::min(x + 2, srcWidth - 1);
Kernel_4x4 ker = {}; //perf: initialization is negligible
ker.a = s_m1[x_m1]; //read sequentially from memory as far as possible
ker.b = s_m1[x];
ker.c = s_m1[x_p1];
ker.d = s_m1[x_p2];
ker.e = s_0[x_m1];
ker.f = s_0[x];
ker.g = s_0[x_p1];
ker.h = s_0[x_p2];
ker.i = s_p1[x_m1];
ker.j = s_p1[x];
ker.k = s_p1[x_p1];
ker.l = s_p1[x_p2];
ker.m = s_p2[x_m1];
ker.n = s_p2[x];
ker.o = s_p2[x_p1];
ker.p = s_p2[x_p2];
const BlendResult res = preProcessCorners<ColorDistance>(ker, cfg);
/*
preprocessing blend result:
---------
| F | G | //evalute corner between F, G, J, K
----|---| //input pixel is at position F
| J | K |
---------
*/
setTopR(preProcBuffer[x], res.blend_j);
if (x + 1 < bufferSize)
setTopL(preProcBuffer[x + 1], res.blend_k);
}
}
//------------------------------------------------------------------------------------
for (int y = yFirst; y < yLast; ++y)
{
uint32_t* out = trg + Scaler::scale * y * trgWidth; //consider MT "striped" access
const uint32_t* s_m1 = src + srcWidth * std::max(y - 1, 0);
const uint32_t* s_0 = src + srcWidth * y; //center line
const uint32_t* s_p1 = src + srcWidth * std::min(y + 1, srcHeight - 1);
const uint32_t* s_p2 = src + srcWidth * std::min(y + 2, srcHeight - 1);
unsigned char blend_xy1 = 0; //corner blending for current (x, y + 1) position
for (int x = 0; x < srcWidth; ++x, out += Scaler::scale)
{
#ifdef WIN32
#ifndef NDEBUG
breakIntoDebugger = debugPixelX == x && debugPixelY == y;
#endif
#endif
//all those bounds checks have only insignificant impact on performance!
const int x_m1 = std::max(x - 1, 0); //perf: prefer array indexing to additional pointers!
const int x_p1 = std::min(x + 1, srcWidth - 1);
const int x_p2 = std::min(x + 2, srcWidth - 1);
Kernel_4x4 ker4 = {}; //perf: initialization is negligible
ker4.a = s_m1[x_m1]; //read sequentially from memory as far as possible
ker4.b = s_m1[x];
ker4.c = s_m1[x_p1];
ker4.d = s_m1[x_p2];
ker4.e = s_0[x_m1];
ker4.f = s_0[x];
ker4.g = s_0[x_p1];
ker4.h = s_0[x_p2];
ker4.i = s_p1[x_m1];
ker4.j = s_p1[x];
ker4.k = s_p1[x_p1];
ker4.l = s_p1[x_p2];
ker4.m = s_p2[x_m1];
ker4.n = s_p2[x];
ker4.o = s_p2[x_p1];
ker4.p = s_p2[x_p2];
//evaluate the four corners on bottom-right of current pixel
unsigned char blend_xy = 0; //for current (x, y) position
{
const BlendResult res = preProcessCorners<ColorDistance>(ker4, cfg);
/*
preprocessing blend result:
---------
| F | G | //evalute corner between F, G, J, K
----|---| //current input pixel is at position F
| J | K |
---------
*/
blend_xy = preProcBuffer[x];
setBottomR(blend_xy, res.blend_f); //all four corners of (x, y) have been determined at this point due to processing sequence!
setTopR(blend_xy1, res.blend_j); //set 2nd known corner for (x, y + 1)
preProcBuffer[x] = blend_xy1; //store on current buffer position for use on next row
blend_xy1 = 0;
setTopL(blend_xy1, res.blend_k); //set 1st known corner for (x + 1, y + 1) and buffer for use on next column
if (x + 1 < bufferSize) //set 3rd known corner for (x + 1, y)
setBottomL(preProcBuffer[x + 1], res.blend_g);
}
//fill block of size scale * scale with the given color
fillBlock(out, trgWidth * sizeof(uint32_t), ker4.f, Scaler::scale, Scaler::scale);
//place *after* preprocessing step, to not overwrite the results while processing the the last pixel!
//blend four corners of current pixel
if (blendingNeeded(blend_xy)) //good 5% perf-improvement
{
Kernel_3x3 ker3 = {}; //perf: initialization is negligible
ker3.a = ker4.a;
ker3.b = ker4.b;
ker3.c = ker4.c;
ker3.d = ker4.e;
ker3.e = ker4.f;
ker3.f = ker4.g;
ker3.g = ker4.i;
ker3.h = ker4.j;
ker3.i = ker4.k;
blendPixel<Scaler, ColorDistance, ROT_0 >(ker3, out, trgWidth, blend_xy, cfg);
blendPixel<Scaler, ColorDistance, ROT_90 >(ker3, out, trgWidth, blend_xy, cfg);
blendPixel<Scaler, ColorDistance, ROT_180>(ker3, out, trgWidth, blend_xy, cfg);
blendPixel<Scaler, ColorDistance, ROT_270>(ker3, out, trgWidth, blend_xy, cfg);
}
}
}
}
//------------------------------------------------------------------------------------
template <class ColorGradient>
struct Scaler2x : public ColorGradient
{
static const int scale = 2;
template <unsigned int M, unsigned int N> //bring template function into scope for GCC
static void alphaGrad(uint32_t& pixBack, uint32_t pixFront) { ColorGradient::template alphaGrad<M, N>(pixBack, pixFront); }
template <class OutputMatrix>
static void blendLineShallow(uint32_t col, OutputMatrix& out)
{
alphaGrad<1, 4>(out.template ref<scale - 1, 0>(), col);
alphaGrad<3, 4>(out.template ref<scale - 1, 1>(), col);
}
template <class OutputMatrix>
static void blendLineSteep(uint32_t col, OutputMatrix& out)
{
alphaGrad<1, 4>(out.template ref<0, scale - 1>(), col);
alphaGrad<3, 4>(out.template ref<1, scale - 1>(), col);
}
template <class OutputMatrix>
static void blendLineSteepAndShallow(uint32_t col, OutputMatrix& out)
{
alphaGrad<1, 4>(out.template ref<1, 0>(), col);
alphaGrad<1, 4>(out.template ref<0, 1>(), col);
alphaGrad<5, 6>(out.template ref<1, 1>(), col); //[!] fixes 7/8 used in xBR
}
template <class OutputMatrix>
static void blendLineDiagonal(uint32_t col, OutputMatrix& out)
{
alphaGrad<1, 2>(out.template ref<1, 1>(), col);
}
template <class OutputMatrix>
static void blendCorner(uint32_t col, OutputMatrix& out)
{
//model a round corner
alphaGrad<21, 100>(out.template ref<1, 1>(), col); //exact: 1 - pi/4 = 0.2146018366
}
};
template <class ColorGradient>
struct Scaler3x : public ColorGradient
{
static const int scale = 3;
template <unsigned int M, unsigned int N> //bring template function into scope for GCC
static void alphaGrad(uint32_t& pixBack, uint32_t pixFront) { ColorGradient::template alphaGrad<M, N>(pixBack, pixFront); }
template <class OutputMatrix>
static void blendLineShallow(uint32_t col, OutputMatrix& out)
{
alphaGrad<1, 4>(out.template ref<scale - 1, 0>(), col);
alphaGrad<1, 4>(out.template ref<scale - 2, 2>(), col);
alphaGrad<3, 4>(out.template ref<scale - 1, 1>(), col);
out.template ref<scale - 1, 2>() = col;
}
template <class OutputMatrix>
static void blendLineSteep(uint32_t col, OutputMatrix& out)
{
alphaGrad<1, 4>(out.template ref<0, scale - 1>(), col);
alphaGrad<1, 4>(out.template ref<2, scale - 2>(), col);
alphaGrad<3, 4>(out.template ref<1, scale - 1>(), col);
out.template ref<2, scale - 1>() = col;
}
template <class OutputMatrix>
static void blendLineSteepAndShallow(uint32_t col, OutputMatrix& out)
{
alphaGrad<1, 4>(out.template ref<2, 0>(), col);
alphaGrad<1, 4>(out.template ref<0, 2>(), col);
alphaGrad<3, 4>(out.template ref<2, 1>(), col);
alphaGrad<3, 4>(out.template ref<1, 2>(), col);
out.template ref<2, 2>() = col;
}
template <class OutputMatrix>
static void blendLineDiagonal(uint32_t col, OutputMatrix& out)
{
alphaGrad<1, 8>(out.template ref<1, 2>(), col); //conflict with other rotations for this odd scale
alphaGrad<1, 8>(out.template ref<2, 1>(), col);
alphaGrad<7, 8>(out.template ref<2, 2>(), col); //
}
template <class OutputMatrix>
static void blendCorner(uint32_t col, OutputMatrix& out)
{
//model a round corner
alphaGrad<45, 100>(out.template ref<2, 2>(), col); //exact: 0.4545939598
//alphaGrad<7, 256>(out.template ref<2, 1>(), col); //0.02826017254 -> negligible + avoid conflicts with other rotations for this odd scale
//alphaGrad<7, 256>(out.template ref<1, 2>(), col); //0.02826017254
}
};
template <class ColorGradient>
struct Scaler4x : public ColorGradient
{
static const int scale = 4;
template <unsigned int M, unsigned int N> //bring template function into scope for GCC
static void alphaGrad(uint32_t& pixBack, uint32_t pixFront) { ColorGradient::template alphaGrad<M, N>(pixBack, pixFront); }
template <class OutputMatrix>
static void blendLineShallow(uint32_t col, OutputMatrix& out)
{
alphaGrad<1, 4>(out.template ref<scale - 1, 0>(), col);
alphaGrad<1, 4>(out.template ref<scale - 2, 2>(), col);
alphaGrad<3, 4>(out.template ref<scale - 1, 1>(), col);
alphaGrad<3, 4>(out.template ref<scale - 2, 3>(), col);
out.template ref<scale - 1, 2>() = col;
out.template ref<scale - 1, 3>() = col;
}
template <class OutputMatrix>
static void blendLineSteep(uint32_t col, OutputMatrix& out)
{
alphaGrad<1, 4>(out.template ref<0, scale - 1>(), col);
alphaGrad<1, 4>(out.template ref<2, scale - 2>(), col);
alphaGrad<3, 4>(out.template ref<1, scale - 1>(), col);
alphaGrad<3, 4>(out.template ref<3, scale - 2>(), col);
out.template ref<2, scale - 1>() = col;
out.template ref<3, scale - 1>() = col;
}
template <class OutputMatrix>
static void blendLineSteepAndShallow(uint32_t col, OutputMatrix& out)
{
alphaGrad<3, 4>(out.template ref<3, 1>(), col);
alphaGrad<3, 4>(out.template ref<1, 3>(), col);
alphaGrad<1, 4>(out.template ref<3, 0>(), col);
alphaGrad<1, 4>(out.template ref<0, 3>(), col);
alphaGrad<1, 3>(out.template ref<2, 2>(), col); //[!] fixes 1/4 used in xBR
out.template ref<3, 3>() = col;
out.template ref<3, 2>() = col;
out.template ref<2, 3>() = col;
}
template <class OutputMatrix>
static void blendLineDiagonal(uint32_t col, OutputMatrix& out)
{
alphaGrad<1, 2>(out.template ref<scale - 1, scale / 2 >(), col);
alphaGrad<1, 2>(out.template ref<scale - 2, scale / 2 + 1>(), col);
out.template ref<scale - 1, scale - 1>() = col;
}
template <class OutputMatrix>
static void blendCorner(uint32_t col, OutputMatrix& out)
{
//model a round corner
alphaGrad<68, 100>(out.template ref<3, 3>(), col); //exact: 0.6848532563
alphaGrad< 9, 100>(out.template ref<3, 2>(), col); //0.08677704501
alphaGrad< 9, 100>(out.template ref<2, 3>(), col); //0.08677704501
}
};
template <class ColorGradient>
struct Scaler5x : public ColorGradient
{
static const int scale = 5;
template <unsigned int M, unsigned int N> //bring template function into scope for GCC
static void alphaGrad(uint32_t& pixBack, uint32_t pixFront) { ColorGradient::template alphaGrad<M, N>(pixBack, pixFront); }
template <class OutputMatrix>
static void blendLineShallow(uint32_t col, OutputMatrix& out)
{
alphaGrad<1, 4>(out.template ref<scale - 1, 0>(), col);
alphaGrad<1, 4>(out.template ref<scale - 2, 2>(), col);
alphaGrad<1, 4>(out.template ref<scale - 3, 4>(), col);
alphaGrad<3, 4>(out.template ref<scale - 1, 1>(), col);
alphaGrad<3, 4>(out.template ref<scale - 2, 3>(), col);
out.template ref<scale - 1, 2>() = col;
out.template ref<scale - 1, 3>() = col;
out.template ref<scale - 1, 4>() = col;
out.template ref<scale - 2, 4>() = col;
}
template <class OutputMatrix>
static void blendLineSteep(uint32_t col, OutputMatrix& out)
{
alphaGrad<1, 4>(out.template ref<0, scale - 1>(), col);
alphaGrad<1, 4>(out.template ref<2, scale - 2>(), col);
alphaGrad<1, 4>(out.template ref<4, scale - 3>(), col);
alphaGrad<3, 4>(out.template ref<1, scale - 1>(), col);
alphaGrad<3, 4>(out.template ref<3, scale - 2>(), col);
out.template ref<2, scale - 1>() = col;
out.template ref<3, scale - 1>() = col;
out.template ref<4, scale - 1>() = col;
out.template ref<4, scale - 2>() = col;
}
template <class OutputMatrix>
static void blendLineSteepAndShallow(uint32_t col, OutputMatrix& out)
{
alphaGrad<1, 4>(out.template ref<0, scale - 1>(), col);
alphaGrad<1, 4>(out.template ref<2, scale - 2>(), col);
alphaGrad<3, 4>(out.template ref<1, scale - 1>(), col);
alphaGrad<1, 4>(out.template ref<scale - 1, 0>(), col);
alphaGrad<1, 4>(out.template ref<scale - 2, 2>(), col);
alphaGrad<3, 4>(out.template ref<scale - 1, 1>(), col);
alphaGrad<2, 3>(out.template ref<3, 3>(), col);
out.template ref<2, scale - 1>() = col;
out.template ref<3, scale - 1>() = col;
out.template ref<4, scale - 1>() = col;
out.template ref<scale - 1, 2>() = col;
out.template ref<scale - 1, 3>() = col;
}
template <class OutputMatrix>
static void blendLineDiagonal(uint32_t col, OutputMatrix& out)
{
alphaGrad<1, 8>(out.template ref<scale - 1, scale / 2 >(), col); //conflict with other rotations for this odd scale
alphaGrad<1, 8>(out.template ref<scale - 2, scale / 2 + 1>(), col);
alphaGrad<1, 8>(out.template ref<scale - 3, scale / 2 + 2>(), col); //
alphaGrad<7, 8>(out.template ref<4, 3>(), col);
alphaGrad<7, 8>(out.template ref<3, 4>(), col);
out.template ref<4, 4>() = col;
}
template <class OutputMatrix>
static void blendCorner(uint32_t col, OutputMatrix& out)
{
//model a round corner
alphaGrad<86, 100>(out.template ref<4, 4>(), col); //exact: 0.8631434088
alphaGrad<23, 100>(out.template ref<4, 3>(), col); //0.2306749731
alphaGrad<23, 100>(out.template ref<3, 4>(), col); //0.2306749731
//alphaGrad<1, 64>(out.template ref<4, 2>(), col); //0.01676812367 -> negligible + avoid conflicts with other rotations for this odd scale
//alphaGrad<1, 64>(out.template ref<2, 4>(), col); //0.01676812367
}
};
template <class ColorGradient>
struct Scaler6x : public ColorGradient
{
static const int scale = 6;
template <unsigned int M, unsigned int N> //bring template function into scope for GCC
static void alphaGrad(uint32_t& pixBack, uint32_t pixFront) { ColorGradient::template alphaGrad<M, N>(pixBack, pixFront); }
template <class OutputMatrix>
static void blendLineShallow(uint32_t col, OutputMatrix& out)
{
alphaGrad<1, 4>(out.template ref<scale - 1, 0>(), col);
alphaGrad<1, 4>(out.template ref<scale - 2, 2>(), col);
alphaGrad<1, 4>(out.template ref<scale - 3, 4>(), col);
alphaGrad<3, 4>(out.template ref<scale - 1, 1>(), col);
alphaGrad<3, 4>(out.template ref<scale - 2, 3>(), col);
alphaGrad<3, 4>(out.template ref<scale - 3, 5>(), col);
out.template ref<scale - 1, 2>() = col;
out.template ref<scale - 1, 3>() = col;
out.template ref<scale - 1, 4>() = col;
out.template ref<scale - 1, 5>() = col;
out.template ref<scale - 2, 4>() = col;
out.template ref<scale - 2, 5>() = col;
}
template <class OutputMatrix>
static void blendLineSteep(uint32_t col, OutputMatrix& out)
{
alphaGrad<1, 4>(out.template ref<0, scale - 1>(), col);
alphaGrad<1, 4>(out.template ref<2, scale - 2>(), col);
alphaGrad<1, 4>(out.template ref<4, scale - 3>(), col);
alphaGrad<3, 4>(out.template ref<1, scale - 1>(), col);
alphaGrad<3, 4>(out.template ref<3, scale - 2>(), col);
alphaGrad<3, 4>(out.template ref<5, scale - 3>(), col);
out.template ref<2, scale - 1>() = col;
out.template ref<3, scale - 1>() = col;
out.template ref<4, scale - 1>() = col;
out.template ref<5, scale - 1>() = col;
out.template ref<4, scale - 2>() = col;
out.template ref<5, scale - 2>() = col;
}
template <class OutputMatrix>
static void blendLineSteepAndShallow(uint32_t col, OutputMatrix& out)
{
alphaGrad<1, 4>(out.template ref<0, scale - 1>(), col);
alphaGrad<1, 4>(out.template ref<2, scale - 2>(), col);
alphaGrad<3, 4>(out.template ref<1, scale - 1>(), col);
alphaGrad<3, 4>(out.template ref<3, scale - 2>(), col);
alphaGrad<1, 4>(out.template ref<scale - 1, 0>(), col);
alphaGrad<1, 4>(out.template ref<scale - 2, 2>(), col);
alphaGrad<3, 4>(out.template ref<scale - 1, 1>(), col);
alphaGrad<3, 4>(out.template ref<scale - 2, 3>(), col);
out.template ref<2, scale - 1>() = col;
out.template ref<3, scale - 1>() = col;
out.template ref<4, scale - 1>() = col;
out.template ref<5, scale - 1>() = col;
out.template ref<4, scale - 2>() = col;
out.template ref<5, scale - 2>() = col;
out.template ref<scale - 1, 2>() = col;
out.template ref<scale - 1, 3>() = col;
}
template <class OutputMatrix>
static void blendLineDiagonal(uint32_t col, OutputMatrix& out)
{
alphaGrad<1, 2>(out.template ref<scale - 1, scale / 2 >(), col);
alphaGrad<1, 2>(out.template ref<scale - 2, scale / 2 + 1>(), col);
alphaGrad<1, 2>(out.template ref<scale - 3, scale / 2 + 2>(), col);
out.template ref<scale - 2, scale - 1>() = col;
out.template ref<scale - 1, scale - 1>() = col;
out.template ref<scale - 1, scale - 2>() = col;
}
template <class OutputMatrix>
static void blendCorner(uint32_t col, OutputMatrix& out)
{
//model a round corner
alphaGrad<97, 100>(out.template ref<5, 5>(), col); //exact: 0.9711013910
alphaGrad<42, 100>(out.template ref<4, 5>(), col); //0.4236372243
alphaGrad<42, 100>(out.template ref<5, 4>(), col); //0.4236372243
alphaGrad< 6, 100>(out.template ref<5, 3>(), col); //0.05652034508
alphaGrad< 6, 100>(out.template ref<3, 5>(), col); //0.05652034508
}
};
//------------------------------------------------------------------------------------
struct ColorDistanceRGB
{
static double dist(uint32_t pix1, uint32_t pix2, double luminanceWeight)
{
return distYCbCrBuffered(pix1, pix2);
//if (pix1 == pix2) //about 4% perf boost
// return 0;
//return distYCbCr(pix1, pix2, luminanceWeight);
}
};
struct ColorDistanceARGB
{
static double dist(uint32_t pix1, uint32_t pix2, double luminanceWeight)
{
const double a1 = getAlpha(pix1) / 255.0 ;
const double a2 = getAlpha(pix2) / 255.0 ;
/*
Requirements for a color distance handling alpha channel: with a1, a2 in [0, 1]
1. if a1 = a2, distance should be: a1 * distYCbCr()
2. if a1 = 0, distance should be: a2 * distYCbCr(black, white) = a2 * 255
3. if a1 = 1, ??? maybe: 255 * (1 - a2) + a2 * distYCbCr()
*/
//return std::min(a1, a2) * distYCbCrBuffered(pix1, pix2) + 255 * abs(a1 - a2);
//=> following code is 15% faster:
const double d = distYCbCrBuffered(pix1, pix2);
if (a1 < a2)
return a1 * d + 255 * (a2 - a1);
else
return a2 * d + 255 * (a1 - a2);
//alternative? return std::sqrt(a1 * a2 * square(distYCbCrBuffered(pix1, pix2)) + square(255 * (a1 - a2)));
}
};
struct ColorDistanceUnbufferedARGB
{
static double dist(uint32_t pix1, uint32_t pix2, double luminanceWeight)
{
const double a1 = getAlpha(pix1) / 255.0 ;
const double a2 = getAlpha(pix2) / 255.0 ;
const double d = distYCbCr(pix1, pix2, luminanceWeight);
if (a1 < a2)
return a1 * d + 255 * (a2 - a1);
else
return a2 * d + 255 * (a1 - a2);
}
};
struct ColorGradientRGB
{
template <unsigned int M, unsigned int N>
static void alphaGrad(uint32_t& pixBack, uint32_t pixFront)
{
pixBack = gradientRGB<M, N>(pixFront, pixBack);
}
};
struct ColorGradientARGB
{
template <unsigned int M, unsigned int N>
static void alphaGrad(uint32_t& pixBack, uint32_t pixFront)
{
pixBack = gradientARGB<M, N>(pixFront, pixBack);
}
};
}
void xbrz::scale(size_t factor, const uint32_t* src, uint32_t* trg, int srcWidth, int srcHeight, ColorFormat colFmt, const xbrz::ScalerCfg& cfg, int yFirst, int yLast)
{
static_assert(SCALE_FACTOR_MAX == 6, "");
switch (colFmt)
{
case ColorFormat::RGB:
switch (factor)
{
case 2:
return scaleImage<Scaler2x<ColorGradientRGB>, ColorDistanceRGB>(src, trg, srcWidth, srcHeight, cfg, yFirst, yLast);
case 3:
return scaleImage<Scaler3x<ColorGradientRGB>, ColorDistanceRGB>(src, trg, srcWidth, srcHeight, cfg, yFirst, yLast);
case 4:
return scaleImage<Scaler4x<ColorGradientRGB>, ColorDistanceRGB>(src, trg, srcWidth, srcHeight, cfg, yFirst, yLast);
case 5:
return scaleImage<Scaler5x<ColorGradientRGB>, ColorDistanceRGB>(src, trg, srcWidth, srcHeight, cfg, yFirst, yLast);
case 6:
return scaleImage<Scaler6x<ColorGradientRGB>, ColorDistanceRGB>(src, trg, srcWidth, srcHeight, cfg, yFirst, yLast);
}
break;
case ColorFormat::ARGB:
switch (factor)
{
case 2:
return scaleImage<Scaler2x<ColorGradientARGB>, ColorDistanceARGB>(src, trg, srcWidth, srcHeight, cfg, yFirst, yLast);
case 3:
return scaleImage<Scaler3x<ColorGradientARGB>, ColorDistanceARGB>(src, trg, srcWidth, srcHeight, cfg, yFirst, yLast);
case 4:
return scaleImage<Scaler4x<ColorGradientARGB>, ColorDistanceARGB>(src, trg, srcWidth, srcHeight, cfg, yFirst, yLast);
case 5:
return scaleImage<Scaler5x<ColorGradientARGB>, ColorDistanceARGB>(src, trg, srcWidth, srcHeight, cfg, yFirst, yLast);
case 6:
return scaleImage<Scaler6x<ColorGradientARGB>, ColorDistanceARGB>(src, trg, srcWidth, srcHeight, cfg, yFirst, yLast);
}
break;
case ColorFormat::ARGB_UNBUFFERED:
switch (factor)
{
case 2:
return scaleImage<Scaler2x<ColorGradientARGB>, ColorDistanceUnbufferedARGB>(src, trg, srcWidth, srcHeight, cfg, yFirst, yLast);
case 3:
return scaleImage<Scaler3x<ColorGradientARGB>, ColorDistanceUnbufferedARGB>(src, trg, srcWidth, srcHeight, cfg, yFirst, yLast);
case 4:
return scaleImage<Scaler4x<ColorGradientARGB>, ColorDistanceUnbufferedARGB>(src, trg, srcWidth, srcHeight, cfg, yFirst, yLast);
case 5:
return scaleImage<Scaler5x<ColorGradientARGB>, ColorDistanceUnbufferedARGB>(src, trg, srcWidth, srcHeight, cfg, yFirst, yLast);
case 6:
return scaleImage<Scaler6x<ColorGradientARGB>, ColorDistanceUnbufferedARGB>(src, trg, srcWidth, srcHeight, cfg, yFirst, yLast);
}
break;
}
assert(false);
}
bool xbrz::equalColorTest(uint32_t col1, uint32_t col2, ColorFormat colFmt, double luminanceWeight, double equalColorTolerance)
{
switch (colFmt)
{
case ColorFormat::RGB:
return ColorDistanceRGB::dist(col1, col2, luminanceWeight) < equalColorTolerance;
case ColorFormat::ARGB:
return ColorDistanceARGB::dist(col1, col2, luminanceWeight) < equalColorTolerance;
case ColorFormat::ARGB_UNBUFFERED:
return ColorDistanceUnbufferedARGB::dist(col1, col2, luminanceWeight) < equalColorTolerance;
}
assert(false);
return false;
}
void xbrz::bilinearScale(const uint32_t* src, int srcWidth, int srcHeight,
/**/ uint32_t* trg, int trgWidth, int trgHeight)
{
bilinearScale(src, srcWidth, srcHeight, srcWidth * sizeof(uint32_t),
trg, trgWidth, trgHeight, trgWidth * sizeof(uint32_t),
0, trgHeight, [](uint32_t pix) { return pix; });
}
void xbrz::nearestNeighborScale(const uint32_t* src, int srcWidth, int srcHeight,
/**/ uint32_t* trg, int trgWidth, int trgHeight)
{
nearestNeighborScale(src, srcWidth, srcHeight, srcWidth * sizeof(uint32_t),
trg, trgWidth, trgHeight, trgWidth * sizeof(uint32_t),
0, trgHeight, [](uint32_t pix) { return pix; });
}
#if 0
//#include <ppl.h>
void bilinearScaleCpu(const uint32_t* src, int srcWidth, int srcHeight,
/**/ uint32_t* trg, int trgWidth, int trgHeight)
{
const int TASK_GRANULARITY = 16;
concurrency::task_group tg;
for (int i = 0; i < trgHeight; i += TASK_GRANULARITY)
tg.run([=]
{
const int iLast = std::min(i + TASK_GRANULARITY, trgHeight);
xbrz::bilinearScale(src, srcWidth, srcHeight, srcWidth * sizeof(uint32_t),
trg, trgWidth, trgHeight, trgWidth * sizeof(uint32_t),
i, iLast, [](uint32_t pix) { return pix; });
});
tg.wait();
}
//Perf: AMP vs CPU: merely ~10% shorter runtime (scaling 1280x800 -> 1920x1080)
//#include <amp.h>
void bilinearScaleAmp(const uint32_t* src, int srcWidth, int srcHeight, //throw concurrency::runtime_exception
/**/ uint32_t* trg, int trgWidth, int trgHeight)
{
//C++ AMP reference: https://msdn.microsoft.com/en-us/library/hh289390.aspx
//introduction to C++ AMP: https://msdn.microsoft.com/en-us/magazine/hh882446.aspx
using namespace concurrency;
//TODO: pitch
if (srcHeight <= 0 || srcWidth <= 0) return;
const float scaleX = static_cast<float>(trgWidth ) / srcWidth;
const float scaleY = static_cast<float>(trgHeight) / srcHeight;
array_view<const uint32_t, 2> srcView(srcHeight, srcWidth, src);
array_view< uint32_t, 2> trgView(trgHeight, trgWidth, trg);
trgView.discard_data();
parallel_for_each(trgView.extent, [=](index<2> idx) restrict(amp) //throw ?
{
const int y = idx[0];
const int x = idx[1];
//Perf notes:
// -> float-based calculation is (almost 2x) faster than double!
// -> no noticeable improvement via tiling: https://msdn.microsoft.com/en-us/magazine/hh882447.aspx
// -> no noticeable improvement with restrict(amp,cpu)
// -> iterating over y-axis only is significantly slower!
// -> pre-calculating x,y-dependent variables in a buffer + array_view<> is ~ 20 % slower!
const int y1 = srcHeight * y / trgHeight;
int y2 = y1 + 1;
if (y2 == srcHeight) --y2;
const float yy1 = y / scaleY - y1;
const float y2y = 1 - yy1;
//-------------------------------------
const int x1 = srcWidth * x / trgWidth;
int x2 = x1 + 1;
if (x2 == srcWidth) --x2;
const float xx1 = x / scaleX - x1;
const float x2x = 1 - xx1;
//-------------------------------------
const float x2xy2y = x2x * y2y;
const float xx1y2y = xx1 * y2y;
const float x2xyy1 = x2x * yy1;
const float xx1yy1 = xx1 * yy1;
auto interpolate = [=](int offset)
{
/*
https://en.wikipedia.org/wiki/Bilinear_interpolation
(c11(x2 - x) + c21(x - x1)) * (y2 - y ) +
(c12(x2 - x) + c22(x - x1)) * (y - y1)
*/
const auto c11 = (srcView(y1, x1) >> (8 * offset)) & 0xff;
const auto c21 = (srcView(y1, x2) >> (8 * offset)) & 0xff;
const auto c12 = (srcView(y2, x1) >> (8 * offset)) & 0xff;
const auto c22 = (srcView(y2, x2) >> (8 * offset)) & 0xff;
return c11 * x2xy2y + c21 * xx1y2y +
c12 * x2xyy1 + c22 * xx1yy1;
};
const float bi = interpolate(0);
const float gi = interpolate(1);
const float ri = interpolate(2);
const float ai = interpolate(3);
const auto b = static_cast<uint32_t>(bi + 0.5f);
const auto g = static_cast<uint32_t>(gi + 0.5f);
const auto r = static_cast<uint32_t>(ri + 0.5f);
const auto a = static_cast<uint32_t>(ai + 0.5f);
trgView(y, x) = (a << 24) | (r << 16) | (g << 8) | b;
});
trgView.synchronize(); //throw ?
}
#endif
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