RGB和HSL之间的转换 C++实现

#define min3v(v1, v2, v3) ((v1)>(v2)? ((v2)>(v3)?(v3):(v2)):((v1)>(v3)?(v3):(v2)))#define max3v(v1, v2, v3) ((v1)<(v2)? ((v2)<(v3)?(v3):(v2)):((v1)<(v3)?(v3):(v1)))typedef struct{ int red; // [0,255] int green; // [0,255] int blue; // [0,255]}COLOR_RGB;typedef struct{ float hue; // [0,360] float saturation; // [0,100] float luminance; // [0,100]}COLOR_HSL;// Converts RGB to HSLstatic void RGBtoHSL(const COLOR_RGB *rgb, COLOR_HSL *hsl){ float h=0, s=0, l=0; // normalizes red-green-blue values float r = rgb->red/255.0f; float g = rgb->green/255.0f; float b = rgb->blue/255.0f; float maxVal = max3v(r, g, b); float minVal = min3v(r, g, b); // hue if(maxVal == minVal) { h = 0; // undefined } else if(maxVal==r && g>=b) { h = 60.0f*(g-b)/(maxVal-minVal); } else if(maxVal==r && g<b) { h = 60.0f*(g-b)/(maxVal-minVal) + 360.0f; } else if(maxVal==g) { h = 60.0f*(b-r)/(maxVal-minVal) + 120.0f; } else if(maxVal==b) { h = 60.0f*(r-g)/(maxVal-minVal) + 240.0f; } // luminance l = (maxVal+minVal)/2.0f; // saturation if(l == 0 || maxVal == minVal) { s = 0; } else if(0<l && l<=0.5f) { s = (maxVal-minVal)/(maxVal+minVal); } else if(l>0.5f) { s = (maxVal-minVal)/(2 - (maxVal+minVal)); //(maxVal-minVal > 0)? } hsl->hue = (h>360)? 360 : ((h<0)?0:h); hsl->saturation = ((s>1)? 1 : ((s<0)?0:s))*100; hsl->luminance = ((l>1)? 1 : ((l<0)?0:l))*100;}// Converts HSL to RGBstatic void HSLtoRGB(const COLOR_HSL *hsl, COLOR_RGB *rgb){ float h = hsl->hue; // h must be [0, 360] float s = hsl->saturation/100.f; // s must be [0, 1] float l = hsl->luminance/100.f; // l must be [0, 1] float R, G, B; if(hsl->saturation == 0) { // achromatic color (gray scale) R = G = B = l*255.0f; } else { float q = (l<0.5f)?(l * (1.0f+s)):(l+s - (l*s)); float p = (2.0f * l) - q; float Hk = h/360.0f; float T[3]; T[0] = Hk + 0.3333333f; // Tr 0.3333333f=1.0/3.0 T[1] = Hk; // Tb T[2] = Hk - 0.3333333f; // Tg for(int i=0; i<3; i++) { if(T[i] < 0) T[i] += 1.0f; if(T[i] > 1) T[i] -= 1.0f; if((T[i]*6) < 1) { T[i] = p + ((q-p)*6.0f*T[i]); } else if((T[i]*2.0f) < 1) //(1.0/6.0)<=T[i] && T[i]<0.5 { T[i] = q; } else if((T[i]*3.0f) < 2) // 0.5<=T[i] && T[i]<(2.0/3.0) { T[i] = p + (q-p) * ((2.0f/3.0f) - T[i]) * 6.0f; } else T[i] = p; } R = T[0]*255.0f; G = T[1]*255.0f; B = T[2]*255.0f; } rgb->red = (int)((R>255)? 255 : ((R<0)?0 : R)); rgb->green = (int)((G>255)? 255 : ((G<0)?0 : G)); rgb->blue = (int)((B>255)? 255 : ((B<0)?0 : B));}// 在Windows系统下，HSL分量的范围是[0，240].参考“画笔”程序，可以看到RGB（红|绿|蓝）// 和HSL（色调|饱和度|亮度）的联系。// 下面的代码，把COLOR_HSL的分量值变为Windows的HSL分量，取值在[0，240]之间，需要：// 下面为COLOR_HSL到Windows的HSL的转换：// win_H = 240 * hsl.hue / 360.f;// win_S = 240 * hsl.saturation / 100.f;// win_L = 240 * hsl.luminance / 100.f;