Demo/sgi/video/colorsys.py

   1 #
   2 # Module color - do color conversions
   3 #
   4
   5 ONE_THIRD=1.0/3.0
   6 ONE_SIXTH=1.0/6.0
   7 TWO_THIRD=2.0/3.0
   8
   9 def rgb_to_yiq(r,g,b):
  10     y = 0.3*r + 0.59*g + 0.11*b
  11     i = 0.6*r - 0.28*g - 0.32*b
  12     q = 0.21*r- 0.52*g + 0.31*b
  13     return (y,i,q)
  14 def yiq_to_rgb(y,i,q):
  15     r = y + 0.948262*i + 0.624013*q
  16     g = y - 0.276066*i - 0.639810*q
  17     b = y - 1.105450*i + 1.729860*q
  18     if r < 0.0: r = 0.0
  19     if g < 0.0: g = 0.0
  20     if b < 0.0: b = 0.0
  21     if r > 1.0: r = 1.0
  22     if g > 1.0: g = 1.0
  23     if b > 1.0: b = 1.0
  24     return (r,g,b)
  25
  26 def _v(m1,m2,hue):
  27     if hue >= 1.0: hue = hue - 1.0
  28     if hue <  0.0: hue = hue + 1.0
  29     if hue < ONE_SIXTH:
  30         return m1 + (m2-m1)*hue*6.0
  31     if hue < 0.5:
  32         return m2
  33     if hue < TWO_THIRD:
  34         return m1 + (m2-m1)*(TWO_THIRD-hue)*6.0
  35     return m1
  36
  37 def rgb_to_hls(r,g,b):
  38     maxc = max(r,g,b)
  39     minc = min(r,g,b)
  40     l = (minc+maxc)/2.0
  41     if minc == maxc:
  42         return 0.0, l, 0.0
  43     if l <= 0.5:
  44         s = (maxc-minc)/(maxc+minc)
  45     else:
  46         s = (maxc-minc)/(2-maxc-minc)
  47     rc = (maxc-r)/(maxc-minc)
  48     gc = (maxc-g)/(maxc-minc)
  49     bc = (maxc-b)/(maxc-minc)
  50     if r == maxc:
  51         h = bc-gc
  52     elif g == maxc:
  53         h = 2.0+rc-bc
  54     else:
  55         h = 4.0+gc-rc
  56     h = h/6.0
  57     if h < 0.0:
  58         h = h + 1.0
  59     return h,l,s
  60 def hls_to_rgb(h,l,s):
  61     if s == 0.0:
  62         return l,l,l
  63     if l <= 0.5:
  64         m2 = l * (1.0+s)
  65     else:
  66         m2 = l+s-(l*s)
  67     m1 = 2.0*l - m2
  68     return (_v(m1,m2,h+ONE_THIRD), _v(m1,m2,h), _v(m1,m2,h-ONE_THIRD))
  69
  70 def rgb_to_hsv(r,g,b):
  71     maxc = max(r,g,b)
  72     minc = min(r,g,b)
  73     v = maxc
  74     if minc == maxc:
  75         return 0.0, 0.0, v
  76     s = (maxc-minc)/maxc
  77     rc = (maxc-r)/(maxc-minc)
  78     gc = (maxc-g)/(maxc-minc)
  79     bc = (maxc-b)/(maxc-minc)
  80     if r == maxc:
  81         h = bc-gc
  82     elif g == maxc:
  83         h = 2.0+rc-bc
  84     else:
  85         h = 4.0+gc-rc
  86     h = h/6.0
  87     if h < 0.0:
  88         h = h + 1.0
  89     return h,s,v
  90 def hsv_to_rgb(h,s,v):
  91     if s == 0.0:
  92         return v,v,v
  93     i = int(h*6.0)
  94     f = (h*6.0)-i
  95     p = v*(1.0-s)
  96     q = v*(1.0-s*f)
  97     t = v*(1.0-s*(1.0-f))
  98     if i in (0,6): return v,t,p
  99     if i == 1: return q,v,p
 100     if i == 2: return p,v,t
 101     if i == 3: return p,q,v
 102     if i == 4: return t,p,v
 103     if i == 5: return v,p,q
 104     print i, h, f
 105     print h, s, v
 106     raise 'Bad color'