File indexing completed on 2024-05-12 15:59:31

 /*
  *  SPDX-FileCopyrightText: 2005 Boudewijn Rempt <boud@valdyas.org>
  *  SPDX-FileCopyrightText: 2014 Wolthera van Hövell <griffinvalley@gmail.com>
  *
  *  SPDX-License-Identifier: LGPL-2.1-or-later
  */
 
 #include "KoColorConversions.h"
 
 #include <cmath>
 
 #include <QtGlobal>
 
 /**
  * A number of often-used conversions between color models
  */
 
 void rgb_to_hsv(int R, int G, int B, int *H, int *S, int *V)
 {
     unsigned int max = R;
     unsigned int min = R;
     unsigned char maxValue = 0; // r = 0, g = 1, b = 2
 
     // find maximum and minimum RGB values
     if (static_cast<unsigned int>(G) > max) {
         max = G;
         maxValue = 1;
     }
 
     if (static_cast<unsigned int>(B) > max) {
         max = B;
         maxValue = 2;
     }
 
     if (static_cast<unsigned int>(G) < min)
         min = G;
 
     if (static_cast<unsigned int>(B) < min)
         min = B;
 
     int delta = max - min;
     *V = max; // value
     *S = max ? (510 * delta + max) / (2 * max) : 0;  // saturation
 
     // calc hue
     if (*S == 0)
         *H = -1; // undefined hue
     else {
         switch (maxValue) {
         case 0:  // red
             if (G >= B)
                 *H = (120 * (G - B) + delta) / (2 * delta);
             else
                 *H = (120 * (G - B + delta) + delta) / (2 * delta) + 300;
             break;
         case 1:  // green
             if (B > R)
                 *H = 120 + (120 * (B - R) + delta) / (2 * delta);
             else
                 *H = 60 + (120 * (B - R + delta) + delta) / (2 * delta);
             break;
         case 2:  // blue
             if (R > G)
                 *H = 240 + (120 * (R - G) + delta) / (2 * delta);
             else
                 *H = 180 + (120 * (R - G + delta) + delta) / (2 * delta);
             break;
         }
     }
 }
 
 void hsv_to_rgb(int H, int S, int V, int *R, int *G, int *B)
 {
     *R = *G = *B = V;
 
     if (S != 0 && H != -1) { // chromatic
 
         if (H >= 360) {
             // angle > 360
             H %= 360;
         }
 
         unsigned int f = H % 60;
         H /= 60;
         unsigned int p = static_cast<unsigned int>(2 * V * (255 - S) + 255) / 510;
 
         if (H & 1) {
             unsigned int q = static_cast<unsigned int>(2 * V * (15300 - S * f) + 15300) / 30600;
             switch (H) {
             case 1:
                 *R = static_cast<int>(q);
                 *G = static_cast<int>(V);
                 *B = static_cast<int>(p);
                 break;
             case 3:
                 *R = static_cast<int>(p);
                 *G = static_cast<int>(q);
                 *B = static_cast<int>(V);
                 break;
             case 5:
                 *R = static_cast<int>(V);
                 *G = static_cast<int>(p);
                 *B = static_cast<int>(q);
                 break;
             }
         } else {
             unsigned int t = static_cast<unsigned int>(2 * V * (15300 - (S * (60 - f))) + 15300) / 30600;
             switch (H) {
             case 0:
                 *R = static_cast<int>(V);
                 *G = static_cast<int>(t);
                 *B = static_cast<int>(p);
                 break;
             case 2:
                 *R = static_cast<int>(p);
                 *G = static_cast<int>(V);
                 *B = static_cast<int>(t);
                 break;
             case 4:
                 *R = static_cast<int>(t);
                 *G = static_cast<int>(p);
                 *B = static_cast<int>(V);
                 break;
             }
         }
     }
 }
 
 #define EPSILON 1e-6
 #define UNDEFINED_HUE -1
 
 void RGBToHSV(float r, float g, float b, float *h, float *s, float *v)
 {
     float max = qMax(r, qMax(g, b));
     float min = qMin(r, qMin(g, b));
 
     *v = max;
 
     if (max > EPSILON) {
         *s = (max - min) / max;
     } else {
         *s = 0;
     }
 
     if (*s < EPSILON) {
         *h = UNDEFINED_HUE;
     } else {
         float delta = max - min;
 
         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)
 {
     if (s < EPSILON || h == UNDEFINED_HUE) {
         // Achromatic case
 
         *r = v;
         *g = v;
         *b = v;
     } else {
         float f, p, q, t;
         int i;
 
         if (h > 360 - EPSILON) {
             h -= 360;
         }
 
         h /= 60;
         i = static_cast<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 = q;
             *b = v;
             break;
         case 4:
             *r = t;
             *g = p;
             *b = v;
             break;
         case 5:
             *r = v;
             *g = p;
             *b = q;
             break;
         }
     }
 }
 
 void rgb_to_hls(quint8 red, quint8 green, quint8 blue, float * hue, float * lightness, float * saturation)
 {
     float r = red / 255.0;
     float g = green / 255.0;
     float b = blue / 255.0;
     float h = 0;
     float l = 0;
     float s = 0;
 
     float max, min, delta;
 
     max = qMax(r, g);
     max = qMax(max, b);
 
     min = qMin(r, g);
     min = qMin(min, b);
 
     delta = max - min;
 
     l = (max + min) / 2;
 
     if (delta == 0) {
         // This is a gray, no chroma...
         h = 0;
         s = 0;
     } else {
         if (l < 0.5)
             s = delta / (max + min);
         else
             s = delta / (2 - max - min);
 
         float delta_r, delta_g, delta_b;
 
         delta_r = ((max - r) / 6) / delta;
         delta_g = ((max - g) / 6) / delta;
         delta_b = ((max - b) / 6) / delta;
 
         if (r == max)
             h = delta_b - delta_g;
         else if (g == max)
             h = (1.0 / 3) + delta_r - delta_b;
         else if (b == max)
             h = (2.0 / 3) + delta_g - delta_r;
 
         if (h < 0) h += 1;
         if (h > 1) h += 1;
 
     }
 
     *hue = h * 360;
     *saturation = s;
     *lightness = l;
 }
 
 float hue_value(float n1, float n2, float hue)
 {
     if (hue > 360)
         hue = hue - 360;
     else if (hue < 0)
         hue = hue + 360;
     if (hue < 60)
         return n1 + (((n2 - n1) * hue) / 60);
     else if (hue < 180)
         return n2;
     else if (hue < 240)
         return n1 + (((n2 - n1) *(240 - hue)) / 60);
     else return n1;
 }
 
 
 void hls_to_rgb(float h, float l, float s, quint8 * r, quint8 * g, quint8 * b)
 {
     float m1, m2;
 
     if (l <= 0.5)
         m2 = l * (1 + s);
     else
         m2 = l + s - l * s;
 
     m1 = 2 * l - m2;
 
     *r = (quint8)(hue_value(m1, m2, h + 120) * 255 + 0.5);
     *g = (quint8)(hue_value(m1, m2, h) * 255 + 0.5);
     *b = (quint8)(hue_value(m1, m2, h - 120) * 255 + 0.5);
 
 }
 
 void rgb_to_hls(quint8 r, quint8 g, quint8 b, int * h, int * l, int * s)
 {
     float hue, saturation, lightness;
 
     rgb_to_hls(r, g, b, &hue, &lightness, &saturation);
     *h = (int)(hue + 0.5);
     *l = (int)(lightness * 255 + 0.5);
     *s = (int)(saturation * 255 + 0.5);
 }
 
 void hls_to_rgb(int h, int l, int s, quint8 * r, quint8 * g, quint8 * b)
 {
     float hue = h;
     float lightness = l / 255.0;
     float saturation = s / 255.0;
 
     hls_to_rgb(hue, lightness, saturation, r, g, b);
 }
 
 /*
 A Fast HSL-to-RGB Transform
 by Ken Fishkin
 from "Graphics Gems", Academic Press, 1990
 */
 
 void RGBToHSL(float r, float g, float b, float *h, float *s, float *l)
 {
     float v;
     float m;
     float vm;
     float r2, g2, b2;
 
     v = qMax(r, g);
     v = qMax(v, b);
     m = qMin(r, g);
     m = qMin(m, b);
 
     if ((*l = (m + v) / 2.0) <= 0.0) {
         *h = UNDEFINED_HUE;
         *s = 0;
         return;
     }
     if ((*s = vm = v - m) > 0.0) {
         *s /= (*l <= 0.5) ? (v + m) :
               (2.0 - v - m) ;
     } else {
         *h = UNDEFINED_HUE;
         return;
     }
 
 
     r2 = (v - r) / vm;
     g2 = (v - g) / vm;
     b2 = (v - b) / vm;
 
     if (r == v)
         *h = (g == m ? 5.0 + b2 : 1.0 - g2);
     else if (g == v)
         *h = (b == m ? 1.0 + r2 : 3.0 - b2);
     else
         *h = (r == m ? 3.0 + g2 : 5.0 - r2);
 
     *h *= 60;
     *h = fmod(*h, 360.0);
 }
 
 void HSLToRGB(float h, float sl, float l, float *r, float *g, float *b)
 
 {
     float v;
 
     v = (l <= 0.5) ? (l * (1.0 + sl)) : (l + sl - l * sl);
     if (v <= 0) {
         *r = *g = *b = 0.0;
     } else {
         float m;
         float sv;
         int sextant;
         float fract, vsf, mid1, mid2;
 
         m = l + l - v;
         sv = (v - m) / v;
         h = fmod(h, 360.0);
         h /= 60.0;
         sextant = static_cast<int>(h);
         fract = h - sextant;
         vsf = v * sv * fract;
         mid1 = m + vsf;
         mid2 = v - vsf;
         switch (sextant) {
         case 0: *r = v; *g = mid1; *b = m; break;
         case 1: *r = mid2; *g = v; *b = m; break;
         case 2: *r = m; *g = v; *b = mid1; break;
         case 3: *r = m; *g = mid2; *b = v; break;
         case 4: *r = mid1; *g = m; *b = v; break;
         case 5: *r = v; *g = m; *b = mid2; break;
         }
     }
 }
 
 //functions for converting from and back to HSI
 void HSIToRGB(const qreal h,const qreal s, const qreal i, qreal *red, qreal *green, qreal *blue)
 {//This function takes H, S and I values, which are converted to rgb.
     qreal onethird = 1.0/3.0;
     HSYToRGB(h, s, i, red, green, blue, onethird, onethird, onethird);
 }
 void RGBToHSI(qreal r,qreal g, qreal b, qreal *h, qreal *s, qreal *i)
 {
     qreal onethird = 1.0/3.0;
     RGBToHSY(r, g, b, h, s, i, onethird, onethird, onethird);
 
 }
 //functions for converting from and back to hsy'
 void HSYToRGB(const qreal h,const qreal s, const qreal y, qreal *red, qreal *green, qreal *blue, qreal R, qreal G, qreal B)
 {//This function takes H, S and Y values, which are converted to rgb.
 //Those are then used to create a qcolor.
     qreal hue = 0.0;
     qreal sat = 0.0;
     qreal luma = 0.0;
     if (h>1.0 || h<0.0){hue=fmod(h, 1.0);} else {hue=h;}
     if (s<0.0){sat=0.0;} else {sat=s;}
     //if (y>1.0){luma=1.0;}
     if (y<0.0){luma=0.0;}
     else {luma=y;}
     
     qreal segment = 0.166667;//1/6;
     qreal r=0.0;
     qreal g=0.0;
     qreal b=0.0;
 //weights for rgb to Y'(Luma), these are the same weights used in color space maths and the desaturate.
 //This is not luminance or luminosity, it just quacks like it.
     //qreal R=0.299;
     //qreal G=0.587;
     //qreal B=0.114;
 //The intermediary variables for the weighted HSL forumala, based on the HSL in KoColorConversions.
     qreal max_sat, m, fract, luma_a, chroma, x;
     if (hue >= 0.0 && hue < (segment) ) {
             //need to treat this as a weighted hsl thingy.
             //so first things first, at which luma is the maximum saturation for this hue?
             //between R and G+R (yellow)
         max_sat = R + ( G*(hue*6) );    
         if (luma<=max_sat){luma_a = (luma/max_sat)*0.5; chroma=sat*2*luma_a;}
         else {luma_a = ((luma-max_sat)/(1-max_sat)*0.5)+0.5; chroma=sat*(2-2*luma_a);}
 
         fract = hue*6.0;
         x = (1-fabs(fmod(fract,2)-1))*chroma;
         r = chroma; g=x; b=0;
         m = luma-( (R*r)+(B*b)+(G*g) );
         r += m; g += m; b += m;
     } else if (hue >= (segment) && hue < (2.0*segment) ) {
         max_sat = (G+R) - (R*(hue-segment)*6);
 
         if (luma<max_sat) {
             luma_a = (luma/max_sat)*0.5; chroma=sat*(2*luma_a);
         } else {
             luma_a = ((luma-max_sat)/(1-max_sat)*0.5)+0.5; chroma=sat*(2-2*luma_a);
         }
 
         fract = hue*6.0;
         x = (1-fabs(fmod(fract,2)-1) )*chroma;
         r = x; g=chroma; b=0;
         m = luma-( (R*r)+(B*b)+(G*g) );
         r += m; g += m; b += m;
     } else if (hue >= (2.0*segment) && hue < (3.0*segment) ) {
         max_sat = G + (B*(hue-2.0*segment)*6);
         if (luma<max_sat) { 
             luma_a = (luma/max_sat)*0.5; chroma=sat*(2*luma_a);
         } else {
             luma_a = ((luma-max_sat)/(1-max_sat)*0.5)+0.5; chroma=sat*(2-2*luma_a);
         }
         fract = hue*6.0;
         x = (1-fabs(fmod(fract,2)-1) )*chroma;
         r = 0; g=chroma; b=x;
         m = luma-( (R*r)+(B*b)+(G*g) );
         r += m; g += m; b += m;
     } else if (hue >= (3.0*segment) && hue < (4.0*segment) ) {
         max_sat = (G+B) - (G*(hue-3.0*segment)*6);  
         if (luma<max_sat){
             luma_a = (luma/max_sat)*0.5; chroma=sat*(2*luma_a);
         } else {
             luma_a = ((luma-max_sat)/(1-max_sat)*0.5)+0.5; chroma=sat*(2-2*luma_a);
         }
 
         fract = hue*6.0;
         x = (1-fabs(fmod(fract,2)-1) )*chroma;
         r = 0; g=x; b=chroma;
         m = luma-( (R*r)+(B*b)+(G*g) );
         r += m; g += m; b += m;
     } else if (hue >= (4.0*segment) && hue < (5*segment) ) {
         max_sat = B + (R*((hue-4.0*segment)*6));    
         if (luma<max_sat) {
             luma_a = (luma/max_sat)*0.5; chroma=sat*(2*luma_a);
         } else {
             luma_a = ((luma-max_sat)/(1-max_sat)*0.5)+0.5; chroma=sat*(2-2*luma_a);
         }
         fract = hue*6.0;
         x = (1-fabs(fmod(fract,2)-1) )*chroma;
         r = x; g=0; b=chroma;
         m = luma-( (R*r)+(B*b)+(G*g) );
         r += m; g += m; b += m;
     } else if (hue >= (5.0*segment) && hue <= 1.0) {
         max_sat = (B+R) - (B*(hue-5.0*segment)*6);  
         if (luma<max_sat){
             luma_a = (luma/max_sat)*0.5; chroma=sat*(2*luma_a);
         } else {
             luma_a = ((luma-max_sat)/(1-max_sat)*0.5)+0.5; chroma=sat*(2-2*luma_a);
         }
         fract = hue*6.0;
         x = (1-fabs(fmod(fract,2)-1) )*chroma;
         r = chroma; g=0; b=x;
         m = luma-( (R*r)+(B*b)+(G*g) );
         r += m; g += m; b += m;
     } else {
         r=0.0;
         g=0.0;
         b=0.0;
     }
 
     //dbgPigment<<"red: "<<r<<", green: "<<g<<", blue: "<<b;
     //if (r>1.0){r=1.0;}
     //if (g>1.0){g=1.0;}
     //if (b>1.0){b=1.0;}
     //don't limit upwards due to floating point.
     if (r<0.0){r=0.0;}
     if (g<0.0){g=0.0;}
     if (b<0.0){b=0.0;}
 
     *red=r;
     *green=g;
     *blue=b;
 }
 void RGBToHSY(const qreal r,const qreal g,const qreal b, qreal *h, qreal *s, qreal *y, qreal R, qreal G, qreal B)
 {
 //This is LUMA btw, not Luminance.
 //Using these RGB values, we calculate the H, S and I.
     qreal red; qreal green; qreal blue;
     if (r<0.0){red=0.0;} else {red=r;}
     if (g<0.0){green=0.0;} else {green=g;}
     if (b<0.0){blue=0.0;} else {blue=b;}
 
     qreal minval = qMin(r, qMin(g, b));
     qreal maxval = qMax(r, qMax(g, b));
     qreal hue = 0.0;
     qreal sat = 0.0;
     qreal luma = 0.0;
     //weights for rgb, these are the same weights used in color space maths and the desaturate.
     //qreal R=0.299;
     //qreal G=0.587;
     //qreal B=0.114;
     luma=(R*red+G*green+B*blue);
     qreal luma_a=luma;//defined later
     qreal chroma = maxval-minval;
     qreal max_sat=0.5;
     if(chroma==0) {
         hue = 0.0;
         sat = 0.0;
     } else {
         //the following finds the hue
 
         if(maxval==r) {
             //hue = fmod(((g-b)/chroma), 6.0);
             //above doesn't work so let's try this one:
             if (minval==b) {
                 hue = (g-b)/chroma;
             } else {
                 hue = (g-b)/chroma + 6.0;
             }
         } else if(maxval==g) {
             hue = (b-r)/chroma + 2.0;
         } else if(maxval==b) {
             hue = (r-g)/chroma + 4.0;
         }
 
         hue /=6.0;//this makes sure that hue is in the 0-1.0 range.
         //Most HSY formula will tell you that Sat=Chroma. However, this HSY' formula tries to be a
         //weighted HSL formula, where instead of 0.5, we search for a Max_Sat value, which is the Y'
         //at which the saturation is maximum.
         //This requires using the hue, and combining the weighting values accordingly.
         qreal segment = 0.166667;
         if (hue>1.0 || hue<0.0) {
             hue=fmod(hue, 1.0);
         }
 
         if (hue>=0.0 && hue<segment) {
             max_sat = R + G*(hue*6);
         } else if (hue>=segment && hue<(2.0*segment)) {
             max_sat = (G+R) - R*((hue-segment)*6);
         } else if (hue>=(2.0*segment) && hue<(3.0*segment)) {
             max_sat = G + B*((hue-2.0*segment)*6);
         } else if (hue>=(3.0*segment) && hue<(4.0*segment)) {
             max_sat = (B+G) - G*((hue-3.0*segment)*6);
         } else if (hue>=(4.0*segment) && hue<(5.0*segment)) {
             max_sat =  (B) + R*((hue-4.0*segment)*6);
         } else if (hue>=(5.0*segment) && hue<=1.0) {
             max_sat = (R+B) - B*((hue-5.0*segment)*6);
         } else {
             max_sat=0.5;
         }
 
         if(max_sat>1.0 || max_sat<0.0){ //This should not show up during normal use
             max_sat=(fmod(max_sat,1.0));
         } //If it does, it'll try to correct, but it's not good!
 
             //This is weighting the luma for the saturation)
         if (luma <= max_sat) {
             luma_a = (luma/max_sat)*0.5;
         } else{
             luma_a = ((luma-max_sat)/(1-max_sat)*0.5)+0.5;
         }
             
         if (chroma > 0.0) {
             sat = (luma <= max_sat) ? (chroma/ (2*luma_a) ) :(chroma/(2.0-(2*luma_a) ) ) ;
         }
     }
 
     //if (sat>1.0){sat=1.0;}
     //if (luma>1.0){luma=1.0;}
     if (sat<0.0){sat=0.0;}
     if (luma<0.0){luma=0.0;}
 
     *h=hue;
     *s=sat;
     *y=luma;
 
 
 }
 //Extra: Functions for converting from and back to HCI. Where the HSI function is forced cylindrical, HCI is a 
 //double cone. This is for compatibility purposes, and of course, making future programmers who expect a double-cone
 // function less sad. These algorithms were taken from wikipedia.
 
 void HCIToRGB(const qreal h, const qreal c, const qreal i, qreal *red, qreal *green, qreal *blue)
 {
 //This function may not be correct, but it's based on the HCY function on the basis of seeing HCI as similar
 //to the weighted HCY, but assuming that the weights are the same(one-third).
     qreal hue=0.0;
     qreal chroma=0.0;
     qreal intensity=0.0;    
     if(i<0.0){intensity = 0.0;} else{intensity = i;}
     if (h>1.0 || h<0.0){hue=fmod(h, 1.0);} else {hue=h;}
     if(c<0.0){chroma = 0.0;} else{chroma = c;}
     const qreal onethird = 1.0/3.0;
     qreal r=0.0;
     qreal g=0.0;
     qreal b=0.0;
     
     int fract = static_cast<int>(hue*6.0);
     qreal x = (1-fabs(fmod(hue*6.0,2)-1) )*chroma;
     switch (fract) {
         case 0:r = chroma; g=x; b=0;break;
         case 1:r = x; g=chroma; b=0;break;
         case 2:r = 0; g=chroma; b=x;break;
         case 3:r = 0; g=x; b=chroma;break;
         case 4:r = x; g=0; b=chroma;break;
         case 5:r = chroma; g=0; b=x;break;
     }
     qreal m = intensity-( onethird*(r+g+b) );
     r += m; g += m; b += m;
 
     *red=r;
     *green=g;
     *blue=b;
 }
 
 void RGBToHCI(const qreal r,const qreal g,const qreal b, qreal *h, qreal *c, qreal *i)
 {
     qreal minval = qMin(r, qMin(g, b));
     qreal maxval = qMax(r, qMax(g, b));
     qreal hue = 0.0;
     qreal sat = 0.0;
     qreal intensity = 0.0;
     intensity=(r+g+b)/3.0;
     qreal chroma = maxval-minval;
     if(chroma==0) {
         hue = 0.0;
         sat = 0.0;
     } else {
         //the following finds the hue
 
         if(maxval==r) {
             if (minval==b) {
                 hue = (g-b)/chroma;
             } else {
                 hue = (g-b)/chroma + 6.0;
             }
         } else if(maxval==g) {
             hue = (b-r)/chroma + 2.0;
         } else if(maxval==b) {
             hue = (r-g)/chroma + 4.0;
         }
         hue /=6.0;//this makes sure that hue is in the 0-1.0 range.
         sat= 1-(minval/intensity);
     }
 
     *h=hue;
     *c=sat;
     *i=intensity;
 
 }
 void HCYToRGB(const qreal h, const qreal c, const qreal y, qreal *red, qreal *green, qreal *blue, qreal R, qreal G, qreal B)
 {
     qreal hue=0.0;
     qreal chroma=c;
     qreal luma=y;
     if (h>1.0 || h<0.0){hue=(fmod((h*2.0), 2.0))/2.0;} else {hue=h;}
     //const qreal R=0.299;
     //const qreal G=0.587;
     //const qreal B=0.114;
     qreal r=0.0;
     qreal g=0.0;
     qreal b=0.0;
 
     int fract =static_cast<int>(hue*6.0); 
     qreal x = (1-fabs(fmod(hue*6.0,2)-1) )*chroma;
     switch (fract) {
         case 0:r = chroma; g=x; b=0;break;
         case 1:r = x; g=chroma; b=0;break;
         case 2:r = 0; g=chroma; b=x;break;
         case 3:r = 0; g=x; b=chroma;break;
         case 4:r = x; g=0; b=chroma;break;
         case 5:r = chroma; g=0; b=x;break;
     }
     qreal m = luma-( (R*r)+(B*b)+(G*g) );
     r += m; g += m; b += m;
 
     *red=r;
     *green=g;
     *blue=b;
 }
 
 void RGBToHCY(const qreal r,const qreal g,const qreal b, qreal *h, qreal *c, qreal *y, qreal R, qreal G, qreal B)
 {
     qreal minval = qMin(r, qMin(g, b));
     qreal maxval = qMax(r, qMax(g, b));
     qreal hue = 0.0;
     qreal chroma = 0.0;
     qreal luma = 0.0;
     //weights for rgb, these are the same weights used in color space maths and the desaturate.
     //qreal R=0.299;
     //qreal G=0.587;
     //qreal B=0.114;
     luma=(R*r+G*g+B*b);
     chroma = maxval-minval;
 
     if(chroma==0) {
         hue = 0.0;
     }
     else {
         //the following finds the hue
 
         if(maxval==r) {
             //hue = fmod(((g-b)/chroma), 6.0);
             //above doesn't work so let's try this one:
             if (minval==b) {
                 hue = (g-b)/chroma;
             } else {
                 hue = (g-b)/chroma + 6.0;
             }
         } else if(maxval==g) {
             hue = (b-r)/chroma + 2.0;
         } else if(maxval==b) {
             hue = (r-g)/chroma + 4.0;
         }
         hue /=6.0;//this makes sure that hue is in the 0-1.0 range.
     }
     if (chroma<0.0){chroma=0.0;}
     if (luma<0.0){luma=0.0;}
 
     *h=qBound(0.0,hue,1.0);
     *c=chroma;
     *y=luma;
 
 }
 void RGBToYUV(const qreal r,const qreal g,const qreal b, qreal *y, qreal *u, qreal *v, qreal R, qreal G, qreal B)
 {
     qreal uvmax = 0.5;
     qreal luma = R*r+G*g+B*b;
     qreal chromaBlue = uvmax*( (b - luma) / (1.0-B) );
     qreal chromaRed  = uvmax*( (r - luma) / (1.0-R) );
 
     *y = luma; //qBound(0.0,luma,1.0);
     *u = chromaBlue+uvmax;//qBound(0.0,chromaBlue+ uvmax,1.0);
     *v = chromaRed+uvmax;//qBound(0.0,chromaRed + uvmax,1.0);
 }
 void YUVToRGB(const qreal y, const qreal u, const qreal v, qreal *r, qreal *g, qreal *b, qreal R, qreal G, qreal B)
 {
     qreal uvmax = 0.5;
     qreal chromaBlue = u-uvmax;//qBound(0.0,u,1.0)- uvmax;//put into -0.5-+0.5 range//
     qreal chromaRed = v-uvmax;//qBound(0.0,v,1.0)- uvmax;
 
     qreal negB  = 1.0-B;
     qreal negR  = 1.0-R;
     qreal red   = y+(chromaRed  * (negR / uvmax) );
     qreal green = y-(chromaBlue * ((B*negB) / (uvmax*G)) ) - (chromaRed* ((R*negR) / (uvmax*G)));
     qreal blue  = y+(chromaBlue * (negB / uvmax) );
 
     *r=red;//qBound(0.0,red  ,1.0);
     *g=green;//qBound(0.0,green,1.0);
     *b=blue;//qBound(0.0,blue ,1.0);
 }
 
 void LabToLCH(const qreal l, const qreal a, const qreal b, qreal *L, qreal *C, qreal *H)
 {
     qreal atemp =  (a - 0.5)*10.0;//the multiplication is only so that we get out of floating-point maths
     qreal btemp =  (b - 0.5)*10.0;
     *L=qBound(0.0,l,1.0);
     *C=sqrt( pow(atemp,2.0) + pow(btemp,2.0) )*0.1;
     qreal hue = (atan2(btemp,atemp))* 180.0 / M_PI;
     
     if (hue<0.0) {
         hue+=360.0;
     } else {
         hue = fmod(hue, 360.0);
     }
     *H=hue/360.0;
 }
 
 void LCHToLab(const qreal L, const qreal C, const qreal H, qreal *l, qreal *a, qreal *b)
 {
     qreal chroma = qBound(0.0,C,1.0);
     qreal hue = (qBound(0.0,H,1.0)*360.0)* M_PI / 180.0;
     *l=qBound(0.0,L,1.0);
     *a=(chroma * cos(hue) ) + 0.5;
     *b=(chroma * sin(hue) ) + 0.5;
 }
 
 void XYZToxyY(const qreal X, const qreal Y, const qreal Z, qreal *x, qreal *y, qreal *yY)
 {
     qreal Xb = X;
     qreal Yb = Y;
     qreal Zb = Z;
     *x=Xb/(Xb+Yb+Zb);
     *y=Yb/(Xb+Yb+Zb);
     *yY=Yb;
 }  
 void xyYToXYZ(const qreal x, const qreal y, const qreal yY, qreal *X, qreal *Y, qreal *Z)
 {
     qreal xb = x;
     qreal yb = y;
     qreal yYb = yY;
     *X=(xb*yYb)/yb;
     *Z=((1.0-xb-yb)*yYb)/yb;
     *Y=yYb;
 }
 
 void CMYToCMYK(qreal *c, qreal *m, qreal *y, qreal *k)
 {
     qreal cyan, magenta, yellow, key = 1.0;
     cyan    = *c;
     magenta = *m;
     yellow  = *y;
     if ( cyan    < key ) {key = cyan;}
     if ( magenta < key ) {key = magenta;}
     if ( yellow  < key ) {key = yellow;}
     
     if ( key == 1 ) { //Black
         cyan    = 0;
         magenta = 0;
         yellow  = 0;
     }
     else {
         cyan    = ( cyan    - key ) / ( 1.0 - key );
         magenta = ( magenta - key ) / ( 1.0 - key );
         yellow  = ( yellow  - key ) / ( 1.0 - key );
     }
     
     *c=qBound(0.0,cyan   ,1.0);
     *m=qBound(0.0,magenta,1.0);
     *y=qBound(0.0,yellow ,1.0);
     *k=qBound(0.0,key    ,1.0);
 }
 
 /*code from easyrgb.com*/
 void CMYKToCMY(qreal *c, qreal *m, qreal *y, qreal *k)
 {
     qreal key     = *k;
     qreal cyan    = *c;
     qreal magenta = *m;
     qreal yellow  = *y;
     
     cyan    = ( cyan    * ( 1.0 - key ) + key );
     magenta = ( magenta * ( 1.0 - key ) + key );
     yellow  = ( yellow  * ( 1.0 - key ) + key );
     
     *c=qBound(0.0,cyan   ,1.0);
     *m=qBound(0.0,magenta,1.0);
     *y=qBound(0.0,yellow ,1.0);
 }