一、表示顏色的方式有很多種，如RGB，CMYK，HSB，Hex等等
1、RGB：這種表示顏色由三原色構成，通過紅，綠，藍三種顏色分量的不同，組合成不同的顏色，例如，100%紅+100%綠混合可以得到黃色，紅綠藍三種顏色疊加可以得到白色，基本上屏幕顯示色彩都采用這種方式
2、CMYK：也稱作印刷色彩模式，是一種依靠反光的色彩模式，主要用於印刷，和RGB類似，CMY是3種印刷油墨名稱的首字母：青色Cyan、品紅色Magenta、黃色Yellow。而K取的是black最後一個字母，之所以不取首字母，是為了避免與藍色(Blue)混淆。從理論上來說，只需要CMY三種油墨就足夠了，它們三個加在一起就應該得到黑色。但是由於目前制造工藝還不能造出高純度的油墨，CMY相加的結果實際是一種暗紅色。
3、HSB：通過色相（hues），飽和度（saturation），亮度（brightness）來表示顏色
二、下面說說關於各種顏色之間的轉換
1、RGB與CMYK之間的轉換
public static void RGB2CMYK(int red, int green, int blue, out double c, out double m, out double y, out double k)
{
c = (double)(255 - red) / 255;
m = (double)(255 - green) / 255;
y = (double)(255 - blue) / 255;
k = (double)Math.Min(c, Math.Min(m, y));
if (k == 1.0)
{
c = m = y = 0;
}
else
{
c = (c - k) / (1 - k);
m = (m - k) / (1 - k);
y = (y - k) / (1 - k);
}
}
public static void CMYK2RGB(double c, double m, double y, double k, out int r, out int g, out int b)
{
r = Convert.ToInt32((1.0 - c) * (1.0 - k) * 255.0);
g = Convert.ToInt32((1.0 - m) * (1.0 - k) * 255.0);
b = Convert.ToInt32((1.0 - y) * (1.0 - k) * 255.0);
}
2、RGB與HSB之間的轉換
public static void RGB2HSB(int red, int green, int blue, out double hue, out double sat, out double bri)
{
double r = ((double)red / 255.0);
double g = ((double)green / 255.0);
double b = ((double)blue / 255.0);
double max = Math.Max(r, Math.Max(g, b));
double min = Math.Min(r, Math.Min(g, b));
hue = 0.0;
if (max == r && g >= b)
{
if (max - min == 0) hue = 0.0;
else hue = 60 * (g - b) / (max - min);
}
else if (max == r && g < b)
{
hue = 60 * (g - b) / (max - min) + 360;
}
else if (max == g)
{
hue = 60 * (b - r) / (max - min) + 120;
}
else if (max == b)
{
hue = 60 * (r - g) / (max - min) + 240;
}
sat = (max == 0) ? 0.0 : (1.0 - ((double)min / (double)max));
bri = max;
}
public static void HSB2RGB(double hue, double sat, double bri, out int red, out int green ,out int blue)
{
double r = 0;
double g = 0;
double b = 0;
if (sat == 0)
{
r = g = b = bri;
}
else
{
// the color wheel consists of 6 sectors. Figure out which sector you're in.
double sectorPos = hue / 60.0;
int sectorNumber = (int)(Math.Floor(sectorPos));
// get the fractional part of the sector
double fractionalSector = sectorPos - sectorNumber;
// calculate values for the three axes of the color.
double p = bri * (1.0 - sat);
double q = bri * (1.0 - (sat * fractionalSector));
double t = bri * (1.0 - (sat * (1 - fractionalSector)));
// assign the fractional colors to r, g, and b based on the sector the angle is in.
switch (sectorNumber)
{
case 0:
r = bri;
g = t;
b = p;
break;
case 1:
r = q;
g = bri;
b = p;
break;
case 2:
r = p;
g = bri;
b = t;
break;
case 3:
r = p;
g = q;
b = bri;
break;
case 4:
r = t;
g = p;
b = bri;
break;
case 5:
r = bri;
g = p;
b = q;
break;
}
}
red = Convert.ToInt32(r * 255);
green = Convert.ToInt32(g * 255);
blue = Convert.ToInt32(b * 255); ;
}
3、RGB與十六進制Hex表示的轉換
public static string RGB2Hex(int r, int g, int b)
{
return String.Format("#{0:x2}{1:x2}{2:x2}", (int)r, (int)g, (int)b);
}
public static Color Hex2Color(string hexColor)
{
string r, g, b;
if (hexColor != String.Empty)
{
hexColor = hexColor.Trim();
if (hexColor[0] == '#') hexColor = hexColor.Substring(1, hexColor.Length - 1);
r = hexColor.Substring(0, 2);
g = hexColor.Substring(2, 2);
b = hexColor.Substring(4, 2);
r = Convert.ToString(16 * GetIntFromHex(r.Substring(0, 1)) + GetIntFromHex(r.Substring(1, 1)));
g = Convert.ToString(16 * GetIntFromHex(g.Substring(0, 1)) + GetIntFromHex(g.Substring(1, 1)));
b = Convert.ToString(16 * GetIntFromHex(b.Substring(0, 1)) + GetIntFromHex(b.Substring(1, 1)));
return Color.FromArgb(Convert.ToInt32(r), Convert.ToInt32(g), Convert.ToInt32(b));
}
return Color.Empty;
}
private static int GetIntFromHex(string strHex)
{
switch (strHex)
{
case ("A"):
{
return 10;
}
case ("B"):
{
return 11;
}
case ("C"):
{
return 12;
}
case ("D"):
{
return 13;
}
case ("E"):
{
return 14;
}
case ("F"):
{
return 15;
}
default:
{
return int.Parse(strHex);
}
}
}
轉換算法摘自：http://www.codeproject.com/Articles/19045/Manipulating-colors-in-NET-Part-1
