{ RCSid $Id: hsv_rgb.cal,v 2.1 2022/06/01 17:22:31 greg Exp $ } { Convert between HSV (hue, saturation, value) and RGB Hue angles are in degrees, from 0 to 360. From Wikipedia July 2019 } eq(a,b) : if(a-b+1e-6, b-a+1e-6, -1); mod(n,d) : n - floor(n/d)*d; Hprime(M,m, R,G,B) : if(m-M+.001, 0, if(eq(M,R), mod((G-B)/(M-m),6), if(eq(M,G), (B-R)/(M-m) + 2, (R-G)/(M-m) + 4))); Sprime(M,m) : if(M-1e-4, (M-m)/M, 0); H(R,G,B) : 60*Hprime(max(R,G,B),min(R,G,B), R,G,B); S(R,G,B) : Sprime(max(R,G,B),min(R,G,B)); V(R,G,B) : max(R,G,B); frevprime(S,V,k) : V - V*S*max(min(k,4-k,1),0); frev(H,S,V, n) : frevprime(S,V, mod(n+H/60,6)); R(H,S,V) : frev(H,S,V,5); G(H,S,V) : frev(H,S,V,3); B(H,S,V) : frev(H,S,V,1);