两者均在0-255范围内将RGB转换为HSV和将HSV转换为RGB的算法

两者均在0-255范围内将RGB转换为HSV和将HSV转换为RGB的算法

我已经使用了很长一段时间-现在不知道它们从何而来…请注意，输入和输出（以度为单位的角度除外）在0到1.0的范围内。

注意：此代码不对输入进行真正的完整性检查。谨慎行事！

typedef struct {    double r;       // a fraction between 0 and 1    double g;       // a fraction between 0 and 1    double b;       // a fraction between 0 and 1} rgb;typedef struct {    double h;       // angle in degrees    double s;       // a fraction between 0 and 1    double v;       // a fraction between 0 and 1} hsv;static hsv   rgb2hsv(rgb in);static rgb   hsv2rgb(hsv in);hsv rgb2hsv(rgb in){    hsv         out;    double      min, max, delta;    min = in.r < in.g ? in.r : in.g;    min = min  < in.b ? min  : in.b;    max = in.r > in.g ? in.r : in.g;    max = max  > in.b ? max  : in.b;    out.v = max;          // v    delta = max - min;    if (delta < 0.00001)    {        out.s = 0;        out.h = 0; // undefined, maybe nan?        return out;    }    if( max > 0.0 ) { // NOTE: if Max is == 0, this divide would cause a crash        out.s = (delta / max);       // s    } else {        // if max is 0, then r = g = b = 0// s = 0, h is undefined        out.s = 0.0;        out.h = NAN;      // its now undefined        return out;    }    if( in.r >= max )     // > is bogus, just keeps compilor happy        out.h = ( in.g - in.b ) / delta;        // between yellow & magenta    else    if( in.g >= max )        out.h = 2.0 + ( in.b - in.r ) / delta;  // between cyan & yellow    else        out.h = 4.0 + ( in.r - in.g ) / delta;  // between magenta & cyan    out.h *= 60.0;        // degrees    if( out.h < 0.0 )        out.h += 360.0;    return out;}rgb hsv2rgb(hsv in){    double      hh, p, q, t, ff;    long        i;    rgb         out;    if(in.s <= 0.0) {       // < is bogus, just shuts up warnings        out.r = in.v;        out.g = in.v;        out.b = in.v;        return out;    }    hh = in.h;    if(hh >= 360.0) hh = 0.0;    hh /= 60.0;    i = (long)hh;    ff = hh - i;    p = in.v * (1.0 - in.s);    q = in.v * (1.0 - (in.s * ff));    t = in.v * (1.0 - (in.s * (1.0 - ff)));    switch(i) {    case 0:        out.r = in.v;        out.g = t;        out.b = p;        break;    case 1:        out.r = q;        out.g = in.v;        out.b = p;        break;    case 2:        out.r = p;        out.g = in.v;        out.b = t;        break;    case 3:        out.r = p;        out.g = q;        out.b = in.v;        break;    case 4:        out.r = t;        out.g = p;        out.b = in.v;        break;    case 5:    default:        out.r = in.v;        out.g = p;        out.b = q;        break;    }    return out;     }