Mutual conversion between RGB and HSV Color Space Modes

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;
}
}