Is there a built-in C#/.NET System API for HSV to RGB?
It's not built in, but there's there's an open-source C# library called ColorMine which makes converting between color spaces pretty easy.
Rgb to Hsv:
var rgb = new Rgb {R = 123, G = 11, B = 7};
var hsv = rgb.To<Hsv>();
Hsv to Rgb:
var hsv = new Hsv { H = 360, S = .5, L = .17 }
var rgb = hsv.to<Rgb>();
I don't think there's a method doing this in the .NET framework.
Check out Converting HSV to RGB colour using C#
This is the implementation code,
void HsvToRgb(double h, double S, double V, out int r, out int g, out int b)
{
double H = h;
while (H < 0) { H += 360; };
while (H >= 360) { H -= 360; };
double R, G, B;
if (V <= 0)
{ R = G = B = 0; }
else if (S <= 0)
{
R = G = B = V;
}
else
{
double hf = H / 60.0;
int i = (int)Math.Floor(hf);
double f = hf - i;
double pv = V * (1 - S);
double qv = V * (1 - S * f);
double tv = V * (1 - S * (1 - f));
switch (i)
{
// Red is the dominant color
case 0:
R = V;
G = tv;
B = pv;
break;
// Green is the dominant color
case 1:
R = qv;
G = V;
B = pv;
break;
case 2:
R = pv;
G = V;
B = tv;
break;
// Blue is the dominant color
case 3:
R = pv;
G = qv;
B = V;
break;
case 4:
R = tv;
G = pv;
B = V;
break;
// Red is the dominant color
case 5:
R = V;
G = pv;
B = qv;
break;
// Just in case we overshoot on our math by a little, we put these here. Since its a switch it won't slow us down at all to put these here.
case 6:
R = V;
G = tv;
B = pv;
break;
case -1:
R = V;
G = pv;
B = qv;
break;
// The color is not defined, we should throw an error.
default:
//LFATAL("i Value error in Pixel conversion, Value is %d", i);
R = G = B = V; // Just pretend its black/white
break;
}
}
r = Clamp((int)(R * 255.0));
g = Clamp((int)(G * 255.0));
b = Clamp((int)(B * 255.0));
}
/// <summary>
/// Clamp a value to 0-255
/// </summary>
int Clamp(int i)
{
if (i < 0) return 0;
if (i > 255) return 255;
return i;
}
There isn't a built-in method for doing this, but the calculations aren't terribly complex.
Also note that Color's GetHue(), GetSaturation() and GetBrightness() return HSL values, not HSV.
The following C# code converts between RGB and HSV using the algorithms described on Wikipedia.
I already posted this answer here, but I'll copy the code here for quick reference.
The ranges are 0 - 360 for hue, and 0 - 1 for saturation or value.
public static void ColorToHSV(Color color, out double hue, out double saturation, out double value)
{
int max = Math.Max(color.R, Math.Max(color.G, color.B));
int min = Math.Min(color.R, Math.Min(color.G, color.B));
hue = color.GetHue();
saturation = (max == 0) ? 0 : 1d - (1d * min / max);
value = max / 255d;
}
public static Color ColorFromHSV(double hue, double saturation, double value)
{
int hi = Convert.ToInt32(Math.Floor(hue / 60)) % 6;
double f = hue / 60 - Math.Floor(hue / 60);
value = value * 255;
int v = Convert.ToInt32(value);
int p = Convert.ToInt32(value * (1 - saturation));
int q = Convert.ToInt32(value * (1 - f * saturation));
int t = Convert.ToInt32(value * (1 - (1 - f) * saturation));
if (hi == 0)
return Color.FromArgb(255, v, t, p);
else if (hi == 1)
return Color.FromArgb(255, q, v, p);
else if (hi == 2)
return Color.FromArgb(255, p, v, t);
else if (hi == 3)
return Color.FromArgb(255, p, q, v);
else if (hi == 4)
return Color.FromArgb(255, t, p, v);
else
return Color.FromArgb(255, v, p, q);
}