0
0
mirror of https://github.com/python/cpython.git synced 2024-11-25 09:39:56 +01:00
cpython/Lib/colorsys.py
Benjamin Peterson c4bbc8d7dc Merged revisions 68884,68973,68978,69003,69083,69112-69113 via svnmerge from
svn+ssh://pythondev@svn.python.org/python/trunk

........
  r68884 | kristjan.jonsson | 2009-01-24 04:52:26 -0600 (Sat, 24 Jan 2009) | 1 line

  Add a test for UNC import paths, see issue 3677
........
  r68973 | georg.brandl | 2009-01-26 15:29:38 -0600 (Mon, 26 Jan 2009) | 2 lines

  Copy over docs on advanced role features from Sphinx docs.
........
  r68978 | mark.dickinson | 2009-01-26 15:51:56 -0600 (Mon, 26 Jan 2009) | 3 lines

  Issue #5073: Fix occasional failure of bsddb/test/test_lock.py.  Thanks
  Hirokazu Yamamoto for the patch.
........
  r69003 | benjamin.peterson | 2009-01-26 21:07:53 -0600 (Mon, 26 Jan 2009) | 1 line

  excellent place to use a set() #5069
........
  r69083 | benjamin.peterson | 2009-01-28 21:03:00 -0600 (Wed, 28 Jan 2009) | 1 line

  fix download url
........
  r69112 | benjamin.peterson | 2009-01-29 20:02:25 -0600 (Thu, 29 Jan 2009) | 1 line

  pep8tify conditionals
........
  r69113 | benjamin.peterson | 2009-01-29 20:24:39 -0600 (Thu, 29 Jan 2009) | 1 line

  make _tkinter._flatten check the result of PySequence_Size for errors #3880
........
2009-01-30 03:39:35 +00:00

157 lines
3.6 KiB
Python

"""Conversion functions between RGB and other color systems.
This modules provides two functions for each color system ABC:
rgb_to_abc(r, g, b) --> a, b, c
abc_to_rgb(a, b, c) --> r, g, b
All inputs and outputs are triples of floats in the range [0.0...1.0]
(with the exception of I and Q, which covers a slightly larger range).
Inputs outside the valid range may cause exceptions or invalid outputs.
Supported color systems:
RGB: Red, Green, Blue components
YIQ: Luminance, Chrominance (used by composite video signals)
HLS: Hue, Luminance, Saturation
HSV: Hue, Saturation, Value
"""
# References:
# http://en.wikipedia.org/wiki/YIQ
# http://en.wikipedia.org/wiki/HLS_color_space
# http://en.wikipedia.org/wiki/HSV_color_space
__all__ = ["rgb_to_yiq","yiq_to_rgb","rgb_to_hls","hls_to_rgb",
"rgb_to_hsv","hsv_to_rgb"]
# Some floating point constants
ONE_THIRD = 1.0/3.0
ONE_SIXTH = 1.0/6.0
TWO_THIRD = 2.0/3.0
# YIQ: used by composite video signals (linear combinations of RGB)
# Y: perceived grey level (0.0 == black, 1.0 == white)
# I, Q: color components
def rgb_to_yiq(r, g, b):
y = 0.30*r + 0.59*g + 0.11*b
i = 0.60*r - 0.28*g - 0.32*b
q = 0.21*r - 0.52*g + 0.31*b
return (y, i, q)
def yiq_to_rgb(y, i, q):
r = y + 0.948262*i + 0.624013*q
g = y - 0.276066*i - 0.639810*q
b = y - 1.105450*i + 1.729860*q
if r < 0.0:
r = 0.0
if g < 0.0:
g = 0.0
if b < 0.0:
b = 0.0
if r > 1.0:
r = 1.0
if g > 1.0:
g = 1.0
if b > 1.0:
b = 1.0
return (r, g, b)
# HLS: Hue, Luminance, Saturation
# H: position in the spectrum
# L: color lightness
# S: color saturation
def rgb_to_hls(r, g, b):
maxc = max(r, g, b)
minc = min(r, g, b)
# XXX Can optimize (maxc+minc) and (maxc-minc)
l = (minc+maxc)/2.0
if minc == maxc:
return 0.0, l, 0.0
if l <= 0.5:
s = (maxc-minc) / (maxc+minc)
else:
s = (maxc-minc) / (2.0-maxc-minc)
rc = (maxc-r) / (maxc-minc)
gc = (maxc-g) / (maxc-minc)
bc = (maxc-b) / (maxc-minc)
if r == maxc:
h = bc-gc
elif g == maxc:
h = 2.0+rc-bc
else:
h = 4.0+gc-rc
h = (h/6.0) % 1.0
return h, l, s
def hls_to_rgb(h, l, s):
if s == 0.0:
return l, l, l
if l <= 0.5:
m2 = l * (1.0+s)
else:
m2 = l+s-(l*s)
m1 = 2.0*l - m2
return (_v(m1, m2, h+ONE_THIRD), _v(m1, m2, h), _v(m1, m2, h-ONE_THIRD))
def _v(m1, m2, hue):
hue = hue % 1.0
if hue < ONE_SIXTH:
return m1 + (m2-m1)*hue*6.0
if hue < 0.5:
return m2
if hue < TWO_THIRD:
return m1 + (m2-m1)*(TWO_THIRD-hue)*6.0
return m1
# HSV: Hue, Saturation, Value
# H: position in the spectrum
# S: color saturation ("purity")
# V: color brightness
def rgb_to_hsv(r, g, b):
maxc = max(r, g, b)
minc = min(r, g, b)
v = maxc
if minc == maxc:
return 0.0, 0.0, v
s = (maxc-minc) / maxc
rc = (maxc-r) / (maxc-minc)
gc = (maxc-g) / (maxc-minc)
bc = (maxc-b) / (maxc-minc)
if r == maxc:
h = bc-gc
elif g == maxc:
h = 2.0+rc-bc
else:
h = 4.0+gc-rc
h = (h/6.0) % 1.0
return h, s, v
def hsv_to_rgb(h, s, v):
if s == 0.0:
return v, v, v
i = int(h*6.0) # XXX assume int() truncates!
f = (h*6.0) - i
p = v*(1.0 - s)
q = v*(1.0 - s*f)
t = v*(1.0 - s*(1.0-f))
i = i%6
if i == 0:
return v, t, p
if i == 1:
return q, v, p
if i == 2:
return p, v, t
if i == 3:
return p, q, v
if i == 4:
return t, p, v
if i == 5:
return v, p, q
# Cannot get here