github.com/grumpyhome/grumpy@v0.3.1-0.20201208125205-7b775405bdf1/grumpy-runtime-src/third_party/stdlib/colorsys.py (about) 1 """Conversion functions between RGB and other color systems. 2 This modules provides two functions for each color system ABC: 3 rgb_to_abc(r, g, b) --> a, b, c 4 abc_to_rgb(a, b, c) --> r, g, b 5 All inputs and outputs are triples of floats in the range [0.0...1.0] 6 (with the exception of I and Q, which covers a slightly larger range). 7 Inputs outside the valid range may cause exceptions or invalid outputs. 8 Supported color systems: 9 RGB: Red, Green, Blue components 10 YIQ: Luminance, Chrominance (used by composite video signals) 11 HLS: Hue, Luminance, Saturation 12 HSV: Hue, Saturation, Value 13 """ 14 15 # References: 16 # http://en.wikipedia.org/wiki/YIQ 17 # http://en.wikipedia.org/wiki/HLS_color_space 18 # http://en.wikipedia.org/wiki/HSV_color_space 19 20 __all__ = ["rgb_to_yiq","yiq_to_rgb","rgb_to_hls","hls_to_rgb", 21 "rgb_to_hsv","hsv_to_rgb"] 22 23 # Some floating point constants 24 25 ONE_THIRD = 1.0/3.0 26 ONE_SIXTH = 1.0/6.0 27 TWO_THIRD = 2.0/3.0 28 29 # YIQ: used by composite video signals (linear combinations of RGB) 30 # Y: perceived grey level (0.0 == black, 1.0 == white) 31 # I, Q: color components 32 # 33 # There are a great many versions of the constants used in these formulae. 34 # The ones in this library uses constants from the FCC version of NTSC. 35 36 def rgb_to_yiq(r, g, b): 37 y = 0.30*r + 0.59*g + 0.11*b 38 i = 0.74*(r-y) - 0.27*(b-y) 39 q = 0.48*(r-y) + 0.41*(b-y) 40 return (y, i, q) 41 42 def yiq_to_rgb(y, i, q): 43 # r = y + (0.27*q + 0.41*i) / (0.74*0.41 + 0.27*0.48) 44 # b = y + (0.74*q - 0.48*i) / (0.74*0.41 + 0.27*0.48) 45 # g = y - (0.30*(r-y) + 0.11*(b-y)) / 0.59 46 47 r = y + 0.9468822170900693*i + 0.6235565819861433*q 48 g = y - 0.27478764629897834*i - 0.6356910791873801*q 49 b = y - 1.1085450346420322*i + 1.7090069284064666*q 50 51 if r < 0.0: 52 r = 0.0 53 if g < 0.0: 54 g = 0.0 55 if b < 0.0: 56 b = 0.0 57 if r > 1.0: 58 r = 1.0 59 if g > 1.0: 60 g = 1.0 61 if b > 1.0: 62 b = 1.0 63 return (r, g, b) 64 65 66 # HLS: Hue, Luminance, Saturation 67 # H: position in the spectrum 68 # L: color lightness 69 # S: color saturation 70 71 def rgb_to_hls(r, g, b): 72 maxc = max(r, g, b) 73 minc = min(r, g, b) 74 # XXX Can optimize (maxc+minc) and (maxc-minc) 75 l = (minc+maxc)/2.0 76 if minc == maxc: 77 return 0.0, l, 0.0 78 if l <= 0.5: 79 s = (maxc-minc) / (maxc+minc) 80 else: 81 s = (maxc-minc) / (2.0-maxc-minc) 82 rc = (maxc-r) / (maxc-minc) 83 gc = (maxc-g) / (maxc-minc) 84 bc = (maxc-b) / (maxc-minc) 85 if r == maxc: 86 h = bc-gc 87 elif g == maxc: 88 h = 2.0+rc-bc 89 else: 90 h = 4.0+gc-rc 91 h = (h/6.0) % 1.0 92 return h, l, s 93 94 def hls_to_rgb(h, l, s): 95 if s == 0.0: 96 return l, l, l 97 if l <= 0.5: 98 m2 = l * (1.0+s) 99 else: 100 m2 = l+s-(l*s) 101 m1 = 2.0*l - m2 102 return (_v(m1, m2, h+ONE_THIRD), _v(m1, m2, h), _v(m1, m2, h-ONE_THIRD)) 103 104 def _v(m1, m2, hue): 105 hue = hue % 1.0 106 if hue < ONE_SIXTH: 107 return m1 + (m2-m1)*hue*6.0 108 if hue < 0.5: 109 return m2 110 if hue < TWO_THIRD: 111 return m1 + (m2-m1)*(TWO_THIRD-hue)*6.0 112 return m1 113 114 115 # HSV: Hue, Saturation, Value 116 # H: position in the spectrum 117 # S: color saturation ("purity") 118 # V: color brightness 119 120 def rgb_to_hsv(r, g, b): 121 maxc = max(r, g, b) 122 minc = min(r, g, b) 123 v = maxc 124 if minc == maxc: 125 return 0.0, 0.0, v 126 s = (maxc-minc) / maxc 127 rc = (maxc-r) / (maxc-minc) 128 gc = (maxc-g) / (maxc-minc) 129 bc = (maxc-b) / (maxc-minc) 130 if r == maxc: 131 h = bc-gc 132 elif g == maxc: 133 h = 2.0+rc-bc 134 else: 135 h = 4.0+gc-rc 136 h = (h/6.0) % 1.0 137 return h, s, v 138 139 def hsv_to_rgb(h, s, v): 140 if s == 0.0: 141 return v, v, v 142 i = int(h*6.0) # XXX assume int() truncates! 143 f = (h*6.0) - i 144 p = v*(1.0 - s) 145 q = v*(1.0 - s*f) 146 t = v*(1.0 - s*(1.0-f)) 147 i = i%6 148 if i == 0: 149 return v, t, p 150 if i == 1: 151 return q, v, p 152 if i == 2: 153 return p, v, t 154 if i == 3: 155 return p, q, v 156 if i == 4: 157 return t, p, v 158 if i == 5: 159 return v, p, q