| 1 |
greg |
2.1 |
{ RCSid $Id: hsv_rgb.cal,v 1.1 2019/07/24 21:36:28 greg Exp $ } |
| 2 |
|
|
{ |
| 3 |
|
|
Convert between HSV (hue, saturation, value) and RGB |
| 4 |
|
|
Hue angles are in degrees, from 0 to 360. |
| 5 |
|
|
|
| 6 |
|
|
From Wikipedia July 2019 |
| 7 |
|
|
} |
| 8 |
|
|
|
| 9 |
|
|
eq(a,b) : if(a-b+1e-6, b-a+1e-6, -1); |
| 10 |
|
|
mod(n,d) : n - floor(n/d)*d; |
| 11 |
|
|
|
| 12 |
|
|
Hprime(M,m, R,G,B) : if(m-M+.001, 0, |
| 13 |
|
|
if(eq(M,R), mod((G-B)/(M-m),6), |
| 14 |
|
|
if(eq(M,G), (B-R)/(M-m) + 2, |
| 15 |
|
|
(R-G)/(M-m) + 4))); |
| 16 |
|
|
|
| 17 |
|
|
Sprime(M,m) : if(M-1e-4, (M-m)/M, 0); |
| 18 |
|
|
|
| 19 |
|
|
H(R,G,B) : 60*Hprime(max(R,G,B),min(R,G,B), R,G,B); |
| 20 |
|
|
S(R,G,B) : Sprime(max(R,G,B),min(R,G,B)); |
| 21 |
|
|
V(R,G,B) : max(R,G,B); |
| 22 |
|
|
|
| 23 |
|
|
frevprime(S,V,k) : V - V*S*max(min(k,4-k,1),0); |
| 24 |
|
|
frev(H,S,V, n) : frevprime(S,V, mod(n+H/60,6)); |
| 25 |
|
|
|
| 26 |
|
|
R(H,S,V) : frev(H,S,V,5); |
| 27 |
|
|
G(H,S,V) : frev(H,S,V,3); |
| 28 |
|
|
B(H,S,V) : frev(H,S,V,1); |
