HSP color space was created Darel Rex Finley http://alienryderflex.com/hsp.html

tohsp.py

#!/usr/bin/python

import math
import sys

print sys.argv[1]
print sys.argv[2]
print sys.argv[3]

R = float(sys.argv[1])
G = float(sys.argv[2])
B = float(sys.argv[3])

Pr = 0.299
Pg = 0.587
Pb = 0.114

R = (R+1)/256
G = (G+1)/256
B = (B+1)/256

P = math.sqrt(R*R*Pr + G*G*Pg + B*B*Pb)

if R == G and R == B:
    H = 0
    S = 0
else:
    if R >= G and R >= B:  # R is largest
        if B >= G:
            H = 6./6. - 1./6.*(B-G)/(R-G)
            S = 1. - G/R
        else:
            H = 0./6. + 1./6.*(G-B)/(R-B)
            S = 1. - B/R
    else:
        if G >= R and G >= B:  # G is largest
            if R >= B:
                H = 2./6. - 1./6.*(R-B)/(G-B)
                S = 1. - B/G
            else:
                H = 2./6. + 1./6.*(B-R)/(G-R)
                S = 1. - R/G
        else:  # B is largest
            if G >= R:
                H = 4./6. - 1./6.*(G-R)/(B-R)
                S = 1. - R/B
            else:
                H = 4./6. + 1./6.*(R-G)/(B-G)
                S = 1. - G/B

print 'h: ' + str(H*360)
print 's: ' + str(S*100)
print 'p: ' + str(P*100)