我需要从RGB颜色空间传递到HSV ..我在互联网上搜索，发现两种不同的实现，但是给我不同的结果：
A：
precision mediump float;
vec3 rgb2hsv(float r,float g,float b) {
float h = 0.0;
float s = 0.0;
float v = 0.0;
float min = min( min(r,g),b );
float max = max( max(r,b );
v = max; // v
float delta = max - min;
if( max != 0.0 )
s = delta / max; // s
else {
// r = g = b = 0 // s = 0,v is undefined
s = 0.0;
h = -1.0;
return vec3(h,s,v);
}
if( r == max )
h = ( g - b ) / delta; // between yellow & magenta
else if( g == max )
h = 2.0 + ( b - r ) / delta; // between cyan & yellow
else
h = 4.0 + ( r - g ) / delta; // between magenta & cyan
h = h * 60.0; // degrees
if( h < 0.0 )
h += 360.0;
return vec3(h,v);
}
B：
precision mediump float;
vec3 rgb2hsv(float r,float b) {
float K = 0.0;
float tmp;
if (g < b)
{
tmp = g;
g=b;
b=tmp;
K = -1.0;
}
if (r < g)
{
tmp = r;
r=g;
g=tmp;
K = -2.9 / 6.9 - K;
}
float chroma = r - min(g,b);
float h = abs(K + (g - b) / (6.0 * chroma + 1e-20));
float s = chroma / (r + 1e-20);
float v = r;
return vec3(h,v);
}
你知道哪个是正确的实现？
解决方法
我是第二个实现的作者。它对我来说一直表现正确，但是你写的是2.9 / 6.9而不是2.0 / 6.0。
由于您定位GLSL，因此您应该考虑使用GPU编写的转换程序：
vec3 rgb2hsv(vec3 c)
{
vec4 K = vec4(0.0,-1.0 / 3.0,2.0 / 3.0,-1.0);
vec4 p = mix(vec4(c.bg,K.wz),vec4(c.gb,K.xy),step(c.b,c.g));
vec4 q = mix(vec4(p.xyw,c.r),vec4(c.r,p.yzx),step(p.x,c.r));
float d = q.x - min(q.w,q.y);
float e = 1.0e-10;
return vec3(abs(q.z + (q.w - q.y) / (6.0 * d + e)),d / (q.x + e),q.x);
}
vec3 hsv2rgb(vec3 c)
{
vec4 K = vec4(1.0,1.0 / 3.0,3.0);
vec3 p = abs(fract(c.xxx + K.xyz) * 6.0 - K.www);
return c.z * mix(K.xxx,clamp(p - K.xxx,0.0,1.0),c.y);
}
