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v0.8.1
https://github.com/python/cpython
Revision 8497f0a85d97e1d9660bbb450ba9f2dc8b03f87d authored by Giampaolo Rodolà on 07 December 2010, 18:54:43 UTC, committed by Giampaolo Rodolà on 07 December 2010, 18:54:43 UTC
1 parent 1740947
Tip revision: 8497f0a85d97e1d9660bbb450ba9f2dc8b03f87d authored by Giampaolo Rodolà on 07 December 2010, 18:54:43 UTC
backporting security fix of issue 9129 (smtpd module vulnerable to DoS attacks in case of connection bashing)
backporting security fix of issue 9129 (smtpd module vulnerable to DoS attacks in case of connection bashing)
Tip revision: 8497f0a
colorsys.py
"""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
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