  # How do you translate a HSB color to RGB?

Platform: WinForms| Category: Colors

Here is a routine that does this. Note that the conversion is not precise but very close. (Please do post any better algorithm in our forums).

``````
[C#]
// This does not seem to yield accurate results, but very close.
public static void ConvertHSBToRGB(float h, float s, float v, out float r, out float g, out float b)
{
if (s == 0f)
{
// if s = 0 then h is undefined
r = v;
g = v;
b = v;
}
else
{
float hue = (float)h;
if (h == 360.0f)
{
hue = 0.0f;
}
hue /= 60.0f;
int i = (int)Math.Floor((double)hue);
float f = hue - i;
float p = v * (1.0f - s);
float q = v * (1.0f - (s * f));
float t = v * (1.0f - (s * (1 - f)));

switch(i)
{
case 0: r = v; g = t; b = p; break;
case 1: r = q; g = v; b = p; break;
case 2: r = p; g = v; b = t; break;
case 3: r = p; g = q; b = v; break;
case 4: r = t; g = p; b = v; break;
case 5: r = v; g = p; b = q; break;

default: r = 0.0f; g = 0.0f; b = 0.0f; break; /*Trace.Assert(false);*/ // hue out of range
}
}
}
[VB.Net]
Public Shared Sub ConvertHSBToRGB(h As Single, s As Single, v As Single, ByRef r As Single, ByRef g As Single, ByRef b As Single)
If s = 0F Then
’ if s = 0 then h is undefined
r = v
g = v
b = v
Else
Dim hue As Single = System.Convert.ToSingle(h)
If h = 360F Then
hue = 0F
End If
hue /= 60F
Dim i As Integer = Fix(Math.Floor(System.Convert.ToDouble(hue)))
Dim f As Single = hue - i
Dim p As Single = v *(1F - s)
Dim q As Single = v *(1F - s * f)
Dim t As Single = v *(1F - s *(1 - f))

Select Case i
Case 0
r = v
g = t
b = p
Case 1
r = q
g = v
b = p
Case 2
r = p
g = v
b = t
Case 3
r = p
g = q
b = v
Case 4
r = t
g = p
b = v
Case 5
r = v
g = p
b = q

Case Else
r = 0F
g = 0F
b = 0F ’Trace.Assert(false);
’ hue out of range
End Select
End If
End Sub ’ConvertHSBToRGB
``````