(Zt) mutual conversion of RGB and HSV Color Space Modes

From: http://www.cnitblog.com/edaiqingwa/archive/2007/12/11/35643.html
When developing bitmap programs, you often need to convert the color of Bitmap between the RGB and HSV color spaces. The color conversion is implemented by C ++:

RGB color space to HSV color value:

Void rgb2hsv (float R, float g, float B, float & H, float & S, float & V)
{
// R, G, B values are from 0 to 1
// H = [0,360], S = [], V = []
// If S = 0, then H =-1 (undefined)

Float min, Max, Delta, TMP;
TMP = min (R, G );
Min = min (TMP, B );
TMP = max (R, G );
Max = max (TMP, B );
V = max; // v

Delta = max-min;

If (max! = 0)
S = delta/max; // s
Else
{
// R = G = B = 0 // s = 0, V is undefined
S = 0;
H = undefinedcolor;
Return;
}
If (r = max)
H = (G-B)/delta; // between yellow & Magenta
Else if (G = max)
H = 2 + (B-r)/delta; // between cyan & yellow
Else
H = 4 + (r-g)/delta; // between magenta & cyan

H * = 60; // degrees
If (H <0)
H ++ = 360;
}

Convert the HSV color space to the RGB color value:

Void HSV 2rgb (float H, float S, float V, float & R, float & G, float & B)
{
Int I;
Float F, p, q, T;

If (S = 0)
{
// Achromatic (Gray)
R = G = B = V;
Return;
}

H/= 60; // sector 0 to 5
I = floor (h );
F = h-I; // factorial part of H
P = V * (1-S );
Q = V * (1-S * F );
T = V * (1-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;
Default: // case 5:
R = V;
G = P;
B = Q;
Break;
}
}