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70 lines
1.5 KiB
C++
70 lines
1.5 KiB
C++
// This code is in the public domain -- jim@tilander.org
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#include "ColorSpace.h"
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#include "nvimage/Image.h"
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#include "nvmath/Color.h"
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namespace nv
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{
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void ColorSpace::RGBtoYCoCg_R(Image* img)
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{
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const uint w = img->width();
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const uint h = img->height();
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for( uint y=0; y < h; y++ )
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{
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for( uint x=0; x < w; x++ )
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{
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Color32 pixel = img->pixel(x, y);
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const int r = pixel.r;
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const int g = pixel.g;
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const int b = pixel.b;
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const int Co = r - b;
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const int t = b + Co/2;
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const int Cg = g - t;
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const int Y = t + Cg/2;
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// Just saturate the chroma here (we loose out of one bit in each channel)
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// this just means that we won't have as high dynamic range. Perhaps a better option
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// is to loose the least significant bit instead?
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pixel.r = clamp(Co + 128, 0, 255);
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pixel.g = clamp(Cg + 128, 0, 255);
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pixel.b = 0;
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pixel.a = Y;
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}
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}
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}
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void ColorSpace::YCoCg_RtoRGB(Image* img)
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{
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const uint w = img->width();
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const uint h = img->height();
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for( uint y=0; y < h; y++ )
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{
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for( uint x=0; x < w; x++ )
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{
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Color32 pixel = img->pixel(x, y);
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const int Co = (int)pixel.r - 128;
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const int Cg = (int)pixel.g - 128;
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const int Y = pixel.a;
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const int t = Y - Cg/2;
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const int g = Cg + t;
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const int b = t - Co/2;
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const int r = b + Co;
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pixel.r = r;
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pixel.g = g;
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pixel.b = b;
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pixel.a = 1;
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}
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}
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}
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}
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