颜色表示模式有多种，比较常用的(如Windows调色板)有减色系统的RGB(红，绿，蓝)和HSB(色调，饱和度，亮度)，这里简单实现RGB跟HSB之间的转换。
简单算法如下：
C#:
///
/// HSB用float数据类型表示
///
static void RGB2HSB(int r, int g, int b, out float hue, out float sat, out float bri)
{
int minval = Math.Min(r, Math.Min(g, b));
int maxval = Math.Max(r, Math.Max(g, b));
//bri
bri = (float)(maxval + minval) / 510;
//sat
if (maxval == minval)
{
sat = 0.0f;
}
else
{
int sum = maxval + minval;
if (sum > 255)
{
sum = 510 - sum;
}
sat = (float)(maxval - minval) / sum;
}
//hue
if (maxval == minval)
{
hue = 0.0f;
}
else
{
float diff = (float)(maxval - minval);
float rnorm = (maxval - r) / diff;
float gnorm = (maxval - g) / diff;
float bnorm = (maxval - b) / diff;
hue = 0.0f;
if (r == maxval)
{
hue = 60.0f * (6.0f + bnorm - gnorm);
}
if (g == maxval)
{
hue = 60.0f * (2.0f + rnorm - bnorm);
}
if (b == maxval)
{
hue = 60.0f * (4.0f + gnorm - rnorm);
}
if (hue > 360.0f)
{
hue = hue - 360.0f;
}
}
}
///
/// HSB用int数据类型表示，同Winform中的ColorDialog中HSB的表示
///
static void RGB2HSB(int r, int g, int b, out int hue, out int sat, out int bri)
{
float fHue, fSat, fBri;
RGB2HSB(r, g, b, out fHue, out fSat, out fBri);
hue = (int)((fHue / 360.0f) * 240 + 0.5);
sat = (int)(fSat * 241 + 0.5);
bri = (int)(fBri * 241 + 0.5);
if (hue > 239)
{
hue = 239;
}
if (sat > 240)
{
sat = 240;
}
if (bri > 240)
{
bri = 240;
}
}
///
/// 传入的HSB用int型表示，如果用float型表示，可将下面的转换成float过程去掉
///
static void HSB2RGB(int hue, int sat, int bri, out int r, out int g, out int b)
{
//begin:HSB转换为float
if (hue > 239)
{
hue = 239;
}
else
{
if (hue < 0)
{
hue = 0;
}
}
if (sat > 240)
{
sat = 240;
}
else
{
if (sat < 0)
{
sat = 0;
}
}
if (bri > 240)
{
bri = 240;
}
else
{
if (bri < 0)
{
bri = 0;
}
}
float H = hue / 239.0f;
float S = sat / 240.0f;
float L = bri / 240.0f;
//end:HSB转换为float
float red = 0, green = 0, blue = 0;
float d1, d2;
if (L == 0)
{
red = green = blue = 0;
}
else
{
if (S == 0)
{
red = green = blue = L;
}
else
{
d2 = (L <= 0.5f) ? L * (1.0f + S) : L + S - (L * S);
d1 = 2.0f * L - d2;
float[] d3 = new float[] { H + 1.0f / 3.0f, H, H - 1.0f / 3.0f };
float[] rgb = new float[] { 0, 0, 0 };
for (int i = 0; i < 3; i++)
{
if (d3[i] < 0)
{
d3[i] += 1.0f;
}
if (d3[i] > 1.0f)
{
d3[i] -= 1.0f;
}
if (6.0f * d3[i] < 1.0f)
{
rgb[i] = d1 + (d2 - d1) * d3[i] * 6.0f;
}
else
{
if (2.0f * d3[i] < 1.0f)
{
rgb[i] = d2;
}
else
{
if (3.0f * d3[i] < 2.0f)
{
rgb[i] = (d1 + (d2 - d1) * ((2.0f / 3.0f) - d3[i]) * 6.0f);
}
else
{
rgb[i] = d1;
}
}
}
}
red = rgb[0];
green = rgb[1];
blue = rgb[2];
}
}
red = 255.0f * red;
green = 255.0f * green;
blue = 255.0f * blue;
if (red < 1)
{
red = 0.0f;
}
else
{
if (red > 255.0f)
{
red = 255.0f;
}
}
if (green < 1)
{
green = 0.0f;
}
else
{
if (green > 255.0f)
{
green = 255.0f;
}
}
if (blue < 1)
{
blue = 0.0f;
}
else
{
if (blue > 255.0f)
{
blue = 255.0f;
}
}
r = (int)(red + 0.5);
g = (int)(green + 0.5);
b = (int)(blue + 0.5);
}
颜色转化时由于int跟float强制转换以及精度表示等原因，会产生误差。如一个RGB转换为HSB再转换为RGB会于原RGB有一定的误差。
参考资料：Mono
本文作者:飘遥的Blog 来源:http://www.cnblogs.com/zxjay/
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