jsight - 1 year ago 135
C# Question

# Is there a built-in C#/.NET System API for HSV to RGB?

Is there an API built into the .NET framework for converting HSV to RGB? I didn't see a method in System.Drawing.Color for this, but it seems surprising that there wouldn't be one in the platform.

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;
}
``````
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