ColorUtils.cpp

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#include "ColorUtils.h"
#include <common.h>
#include <math.h>

static void Matrix3x3Multiply(float matrix[9], float a, float b, float c, float& x, float& y, float& z) {
   x = matrix[0]*a + matrix[1]*b + matrix[2]*c; 
   y = matrix[3]*a + matrix[4]*b + matrix[5]*c; 
   z = matrix[6]*a + matrix[7]*b + matrix[8]*c; 
}

void RGBtoHSV(float r, float g, float b, float& h, float& s, float& v) {
   float min, max, delta;
   
   min = MIN3(r, g, b);
   max = MAX3(r, g, b);
   v = max;
   
   delta = max - min;
   if (max != 0) {
      s = delta / max;
   }
   else {
      s = 0;
      h = -1;
      return;
   }
   
   if (r == max) {
      h = (g - b) / delta;
   }
   else if (g == max) {
      h = 2 + (b-r) / delta;
   }
   else {
      h = 4 + (r-g) / delta;
   }
   
   h *= 60;
   if (h < 0)
      h += 360;
}

void HSVtoRGB(float h, float s, float v, float& r, float& g, float& b) {
   int i;
   float f, p, q, t;
   if (s == 0) {
      r = g = b = v;
      return;
   }

   h /= 60;
   i = (int)floor(h);
   f = h - i;
   p = v * (1 - s);
   q = v * (1 - s*f);
   t = v * (1 - s*(1-f));

   switch (i) {
      case 0:
         r = v;
         g = t;
         b = p;
         break;
      case 1:
         r = q;
         g = v;
         b = p;
         break;
      case 2:
         r = p;
         g = v;
         b = t;
         break;
      case 3:
         r = p;
         g = p;
         b = v;
      case 4:
         r = t;
         g = p;
         b = v;
      default:
         r = v;
         g = p;
         b = q;
         break;
   }
}

void RGBtoYIQ(float r, float g, float b, float& y, float& i, float& q) {
   static float matrix[] = {
      0.299f,  0.587f,  0.114f,
      0.596f, -0.275f, -0.321f,
      0.212f, -0.523f,  0.311f
   };
   
   Matrix3x3Multiply(matrix, r, g, b, y, i, q);
}

void YIQtoRGB(float y, float i, float q, float& r, float& g, float& b) {
   static float matrix[] = {
      1.0f,  0.956f,  0.621f,
      1.0f, -0.272f, -0.647f,
      1.0f, -1.105f,  1.702f
   };
   
   Matrix3x3Multiply(matrix, y, i, q, r, g, b);
}

void RGBtoXYZ(float r, float g, float b, float& x, float& y, float& z) {
   static float matrix[] = {
      0.412453f, 0.357580f, 0.180423f,
      0.212671f, 0.715160f, 0.072169f,
      0.019334f, 0.119193f, 0.950227f
   };
   
   Matrix3x3Multiply(matrix, r, g, b, x, y, z);
}

void XYZtoRGB(float x, float y, float z, float& r, float& g, float& b) {
   static float matrix[] = {
      3.240479f, -1.537150f, -0.498535f,
      -0.969256f,  1.875992f,  0.041556f,
      0.055648f, -0.204043f,  1.057311f
   };
   
   Matrix3x3Multiply(matrix, x, y, z, r, g, b);
}