www.pudn.com > HSV&RGB.rar > HSV&RGB.c

void Rgb2Hsv(float R, float G, float B, float& H, float& S, float&V) 
{ 
     // r,g,b values are from 0 to 1 
    // h = [0,360], s = [0,1], v = [0,1] 
    // if s == 0, then h = -1 (undefined) 
 
    float min, max, delta,tmp; 
    tmp = min(R, G); 
    min = min( tmp, B ); 
    tmp = max( R, G); 
    max = max(tmp, B ); 
     
    V = max; // v 
 
    delta = max - min; 
 
    if( max != 0 ) 
      S = delta / max; // s 
    else 
    { 
       // r = g = b = 0 // s = 0, v is undefined 
      S = 0; 
      H = UNDEFINEDCOLOR; 
      return; 
    } 
    if( R == max ) 
        H = ( G - B ) / delta; // between yellow & magenta 
   else if( G == max ) 
        H = 2 + ( B - R ) / delta; // between cyan & yellow 
   else 
        H = 4 + ( R - G ) / delta; // between magenta & cyan 
 
    H *= 60; // degrees 
    if( H < 0 ) 
       H += 360; 
} 
 
HSV颜色空间转换为RGB空间颜色值： 
 
void Hsv2Rgb(float H, float S, float V, float &R, float &G, float &B) 
{ 
     int i; 
    float f, p, q, t; 
 
    if( S == 0 )  
    { 
    // achromatic (grey) 
        R = G = B = V; 
        return; 
    } 
 
    H /= 60; // sector 0 to 5 
    i = floor( H ); 
    f = H - i; // factorial part of h 
    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; 
    default: // case 5: 
       R = V; 
       G = p; 
       B = q; 
       break; 
    } 
}