Python code coverage for Lib/colorsys.py

#	count	content
1	n/a	"""Conversion functions between RGB and other color systems.
2	n/a
3	n/a	This modules provides two functions for each color system ABC:
4	n/a
5	n/a	rgb_to_abc(r, g, b) --> a, b, c
6	n/a	abc_to_rgb(a, b, c) --> r, g, b
7	n/a
8	n/a	All inputs and outputs are triples of floats in the range [0.0...1.0]
9	n/a	(with the exception of I and Q, which covers a slightly larger range).
10	n/a	Inputs outside the valid range may cause exceptions or invalid outputs.
11	n/a
12	n/a	Supported color systems:
13	n/a	RGB: Red, Green, Blue components
14	n/a	YIQ: Luminance, Chrominance (used by composite video signals)
15	n/a	HLS: Hue, Luminance, Saturation
16	n/a	HSV: Hue, Saturation, Value
17	n/a	"""
18	n/a
19	n/a	# References:
20	n/a	# http://en.wikipedia.org/wiki/YIQ
21	n/a	# http://en.wikipedia.org/wiki/HLS_color_space
22	n/a	# http://en.wikipedia.org/wiki/HSV_color_space
23	n/a
24	n/a	__all__ = ["rgb_to_yiq","yiq_to_rgb","rgb_to_hls","hls_to_rgb",
25	n/a	"rgb_to_hsv","hsv_to_rgb"]
26	n/a
27	n/a	# Some floating point constants
28	n/a
29	n/a	ONE_THIRD = 1.0/3.0
30	n/a	ONE_SIXTH = 1.0/6.0
31	n/a	TWO_THIRD = 2.0/3.0
32	n/a
33	n/a	# YIQ: used by composite video signals (linear combinations of RGB)
34	n/a	# Y: perceived grey level (0.0 == black, 1.0 == white)
35	n/a	# I, Q: color components
36	n/a	#
37	n/a	# There are a great many versions of the constants used in these formulae.
38	n/a	# The ones in this library uses constants from the FCC version of NTSC.
39	n/a
40	n/a	def rgb_to_yiq(r, g, b):
41	n/a	y = 0.30r + 0.59g + 0.11*b
42	n/a	i = 0.74(r-y) - 0.27(b-y)
43	n/a	q = 0.48(r-y) + 0.41(b-y)
44	n/a	return (y, i, q)
45	n/a
46	n/a	def yiq_to_rgb(y, i, q):
47	n/a	# r = y + (0.27q + 0.41i) / (0.740.41 + 0.270.48)
48	n/a	# b = y + (0.74q - 0.48i) / (0.740.41 + 0.270.48)
49	n/a	# g = y - (0.30(r-y) + 0.11(b-y)) / 0.59
50	n/a
51	n/a	r = y + 0.9468822170900693i + 0.6235565819861433q
52	n/a	g = y - 0.27478764629897834i - 0.6356910791873801q
53	n/a	b = y - 1.1085450346420322i + 1.7090069284064666q
54	n/a
55	n/a	if r < 0.0:
56	n/a	r = 0.0
57	n/a	if g < 0.0:
58	n/a	g = 0.0
59	n/a	if b < 0.0:
60	n/a	b = 0.0
61	n/a	if r > 1.0:
62	n/a	r = 1.0
63	n/a	if g > 1.0:
64	n/a	g = 1.0
65	n/a	if b > 1.0:
66	n/a	b = 1.0
67	n/a	return (r, g, b)
68	n/a
69	n/a
70	n/a	# HLS: Hue, Luminance, Saturation
71	n/a	# H: position in the spectrum
72	n/a	# L: color lightness
73	n/a	# S: color saturation
74	n/a
75	n/a	def rgb_to_hls(r, g, b):
76	n/a	maxc = max(r, g, b)
77	n/a	minc = min(r, g, b)
78	n/a	# XXX Can optimize (maxc+minc) and (maxc-minc)
79	n/a	l = (minc+maxc)/2.0
80	n/a	if minc == maxc:
81	n/a	return 0.0, l, 0.0
82	n/a	if l <= 0.5:
83	n/a	s = (maxc-minc) / (maxc+minc)
84	n/a	else:
85	n/a	s = (maxc-minc) / (2.0-maxc-minc)
86	n/a	rc = (maxc-r) / (maxc-minc)
87	n/a	gc = (maxc-g) / (maxc-minc)
88	n/a	bc = (maxc-b) / (maxc-minc)
89	n/a	if r == maxc:
90	n/a	h = bc-gc
91	n/a	elif g == maxc:
92	n/a	h = 2.0+rc-bc
93	n/a	else:
94	n/a	h = 4.0+gc-rc
95	n/a	h = (h/6.0) % 1.0
96	n/a	return h, l, s
97	n/a
98	n/a	def hls_to_rgb(h, l, s):
99	n/a	if s == 0.0:
100	n/a	return l, l, l
101	n/a	if l <= 0.5:
102	n/a	m2 = l * (1.0+s)
103	n/a	else:
104	n/a	m2 = l+s-(l*s)
105	n/a	m1 = 2.0*l - m2
106	n/a	return (_v(m1, m2, h+ONE_THIRD), _v(m1, m2, h), _v(m1, m2, h-ONE_THIRD))
107	n/a
108	n/a	def _v(m1, m2, hue):
109	n/a	hue = hue % 1.0
110	n/a	if hue < ONE_SIXTH:
111	n/a	return m1 + (m2-m1)hue6.0
112	n/a	if hue < 0.5:
113	n/a	return m2
114	n/a	if hue < TWO_THIRD:
115	n/a	return m1 + (m2-m1)(TWO_THIRD-hue)6.0
116	n/a	return m1
117	n/a
118	n/a
119	n/a	# HSV: Hue, Saturation, Value
120	n/a	# H: position in the spectrum
121	n/a	# S: color saturation ("purity")
122	n/a	# V: color brightness
123	n/a
124	n/a	def rgb_to_hsv(r, g, b):
125	n/a	maxc = max(r, g, b)
126	n/a	minc = min(r, g, b)
127	n/a	v = maxc
128	n/a	if minc == maxc:
129	n/a	return 0.0, 0.0, v
130	n/a	s = (maxc-minc) / maxc
131	n/a	rc = (maxc-r) / (maxc-minc)
132	n/a	gc = (maxc-g) / (maxc-minc)
133	n/a	bc = (maxc-b) / (maxc-minc)
134	n/a	if r == maxc:
135	n/a	h = bc-gc
136	n/a	elif g == maxc:
137	n/a	h = 2.0+rc-bc
138	n/a	else:
139	n/a	h = 4.0+gc-rc
140	n/a	h = (h/6.0) % 1.0
141	n/a	return h, s, v
142	n/a
143	n/a	def hsv_to_rgb(h, s, v):
144	n/a	if s == 0.0:
145	n/a	return v, v, v
146	n/a	i = int(h*6.0) # XXX assume int() truncates!
147	n/a	f = (h*6.0) - i
148	n/a	p = v*(1.0 - s)
149	n/a	q = v(1.0 - sf)
150	n/a	t = v(1.0 - s(1.0-f))
151	n/a	i = i%6
152	n/a	if i == 0:
153	n/a	return v, t, p
154	n/a	if i == 1:
155	n/a	return q, v, p
156	n/a	if i == 2:
157	n/a	return p, v, t
158	n/a	if i == 3:
159	n/a	return p, q, v
160	n/a	if i == 4:
161	n/a	return t, p, v
162	n/a	if i == 5:
163	n/a	return v, p, q
164	n/a	# Cannot get here