rgb-hsv.rar_HSV _HSV TO RGB C_RGB HSV_RGB to HSV_rgb

/****************************************************************************** * 下面两个函数实现rgb和hsv的互相转换 * r,g,b 的值在 0 到 1 之间 * h = [0,360], s = [0,1], v = [0,1] * if s == 0, then h = -1 (undefined) *****************************************************************************/ void RGBtoHSV( float r, float g, float b, float *h, float *s, float *v ) { float min, max, delta; min = MIN( r, g, b ); max = MAX( r, g, b ); *v = max; delta = max - min; if( max != 0 ) *s = delta / max; else { // r = g = b = 0 // s = 0, v 未定义 *s = 0; *h = -1; return; } if( r == max ) *h = ( g - b ) / delta; // 在 yellow & magenta 之间 else if( g == max ) *h = 2 + ( b - r ) / delta; // 在 cyan & yellow 之间 else *h = 4 + ( r - g ) / delta; // 在 magenta & cyan 之间 *h *= 60; // degrees if( *h < 0 ) *h += 360; } void HSVtoRGB( float *r, float *g, float *b, float h, float s, float v ) { int i; float f, p, q, t; if( s == 0 ) { // 灰度 *r = *g = *b = v; return; } h /= 60; // 扇区 0 到 5 i = 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; default: *r = v; *g = p; *b = q; break; } }