public static HSB HSLToHSB(HSL hsl)
{
HSB hsb = new HSB();
hsb.H = (byte)Math.Round(255.0 * hsl.H);
hsb.S = (byte)Math.Round(255.0 * hsl.S);
if (hsl.L < 0.1793)
{
hsb.B = 0;
}
else if (hsl.L > 0.9821)
{
hsb.B = 0xff;
}
else
{
hsb.B = (byte)Math.Round(257.7 + 149.9 * Math.Log(hsl.L));
}
return(hsb);
}
// based on http://www.geekymonkey.com/Programming/CSharp/RGB2HSL_HSL2RGB.htm
// Given H,S,L in range of 0-1
// Returns a Color (RGB struct) in range of 0-255
public static Color HSLToRGB(HSL hsl)
{
double v;
double r, g, b;
r = hsl.L; // default to gray
g = hsl.L;
b = hsl.L;
v = (hsl.L <= 0.5) ? (hsl.L * (1.0 + hsl.S)) : (hsl.L + hsl.S - hsl.L * hsl.S);
if (v > 0)
{
double m;
double sv;
int sextant;
double fract, vsf, mid1, mid2;
m = hsl.L + hsl.L - v;
sv = (v - m) / v;
hsl.H *= 6.0;
sextant = (int)hsl.H;
fract = hsl.H - sextant;
vsf = v * sv * fract;
mid1 = m + vsf;
mid2 = v - vsf;
switch (sextant)
{
case 0:
r = v;
g = mid1;
b = m;
break;
case 1:
r = mid2;
g = v;
b = m;
break;
case 2:
r = m;
g = v;
b = mid1;
break;
case 3:
r = m;
g = mid2;
b = v;
break;
case 4:
r = mid1;
g = m;
b = v;
break;
case 5:
r = v;
g = m;
b = mid2;
break;
}
}
return(Color.FromArgb(Convert.ToByte(r * 255.0f), Convert.ToByte(g * 255.0f), Convert.ToByte(b * 255.0f)));
}
//Conversion from W3C
//H [0..360], S [0..1], L [0..1]
//same conversion like Microsoft .NET Color.Hue, Color.Saturation, Color.Brightness
static HSL RGBToHsl(byte r, byte g, byte b)
{
double min, max, l, s, maxcolor, h = 0;
int i;
double[] rgb = new double[3];
HSL hsl = new HSL();
rgb[0] = r / 255.0;
rgb[1] = g / 255.0;
rgb[2] = b / 255.0;
min = rgb[0];
max = rgb[0];
maxcolor = 0;
for (i = 0; i < rgb.Length - 1; i++)
{
if (rgb[i + 1] <= min)
{
min = rgb[i + 1];
}
if (rgb[i + 1] >= max)
{
max = rgb[i + 1]; maxcolor = i + 1;
}
}
if (r == g && g == b)
{
h = 0;
}
else
{
if (maxcolor == 0)
{
h = (rgb[1] - rgb[2]) / (max - min);
}
if (maxcolor == 1)
{
h = 2 + (rgb[2] - rgb[0]) / (max - min);
}
if (maxcolor == 2)
{
h = 4 + (rgb[0] - rgb[1]) / (max - min);
}
if (double.NaN == h)
{
h = 0;
}
h = h * 60;
if (h < 0)
{
h = h + 360;
}
}
l = (min + max) / 2;
if (min == max)
{
s = 0;
}
else
{
if (l < 0.5)
{
s = (max - min) / (max + min);
}
else
{
s = (max - min) / (2 - max - min);
}
}
hsl.H = h; hsl.S = s; hsl.L = l;
return(hsl);
}
