colorsys.py :  » Language-Interface » ChinesePython » chinesepython2.1.3-0.4 » Lib » Python Open Source

Home
Python Open Source
1.3.1.2 Python
2.Ajax
3.Aspect Oriented
4.Blog
5.Build
6.Business Application
7.Chart Report
8.Content Management Systems
9.Cryptographic
10.Database
11.Development
12.Editor
13.Email
14.ERP
15.Game 2D 3D
16.GIS
17.GUI
18.IDE
19.Installer
20.IRC
21.Issue Tracker
22.Language Interface
23.Log
24.Math
25.Media Sound Audio
26.Mobile
27.Network
28.Parser
29.PDF
30.Project Management
31.RSS
32.Search
33.Security
34.Template Engines
35.Test
36.UML
37.USB Serial
38.Web Frameworks
39.Web Server
40.Web Services
41.Web Unit
42.Wiki
43.Windows
44.XML
Python Open Source » Language Interface » ChinesePython 
ChinesePython » chinesepython2.1.3 0.4 » Lib » 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].
Inputs outside this range may cause exceptions or invalid outputs.

Supported color systems:
RGB: Red, Green, Blue components
YIQ: used by composite video signals
HLS: Hue, Luminance, Saturation
HSV: Hue, Saturation, Value
"""
# References:
# XXX Where's the literature?

__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, S???
# H: position in the spectrum
# L: ???
# S: ???

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: ???
# V: ???

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))
    if i%6 == 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
www.java2java.com | Contact Us
Copyright 2009 - 12 Demo Source and Support. All rights reserved.
All other trademarks are property of their respective owners.