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1 ;;; color.el --- Color manipulation library -*- coding: utf-8; lexical-binding:t -*-
2
3 ;; Copyright (C) 2010-2012 Free Software Foundation, Inc.
4
5 ;; Authors: Julien Danjou <julien@danjou.info>
6 ;; Drew Adams <drew.adams@oracle.com>
7 ;; Keywords: lisp, faces, color, hex, rgb, hsv, hsl, cie-lab, background
8
9 ;; This file is part of GNU Emacs.
10
11 ;; GNU Emacs is free software: you can redistribute it and/or modify
12 ;; it under the terms of the GNU General Public License as published by
13 ;; the Free Software Foundation, either version 3 of the License, or
14 ;; (at your option) any later version.
15
16 ;; GNU Emacs is distributed in the hope that it will be useful,
17 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
18 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
19 ;; GNU General Public License for more details.
20
21 ;; You should have received a copy of the GNU General Public License
22 ;; along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>.
23
24 ;;; Commentary:
25
26 ;; This package provides functions for manipulating colors, including
27 ;; converting between color representations, computing color
28 ;; complements, and computing CIEDE2000 color distances.
29 ;;
30 ;; Supported color representations include RGB (red, green, blue), HSV
31 ;; (hue, saturation, value), HSL (hue, saturation, luminance), sRGB,
32 ;; CIE XYZ, and CIE L*a*b* color components.
33
34 ;;; Code:
35
36 (eval-when-compile
37 (require 'cl))
38
39 ;; Emacs < 23.3
40 (eval-and-compile
41 (unless (boundp 'float-pi)
42 (defconst float-pi (* 4 (atan 1)) "The value of Pi (3.1415926...).")))
43
44 ;;;###autoload
45 (defun color-name-to-rgb (color &optional frame)
46 "Convert COLOR string to a list of normalized RGB components.
47 COLOR should be a color name (e.g. \"white\") or an RGB triplet
48 string (e.g. \"#ff12ec\").
49
50 Normally the return value is a list of three floating-point
51 numbers, (RED GREEN BLUE), each between 0.0 and 1.0 inclusive.
52
53 Optional arg FRAME specifies the frame where the color is to be
54 displayed. If FRAME is omitted or nil, use the selected frame.
55 If FRAME cannot display COLOR, return nil."
56 ;; `colors-values' maximum value is either 65535 or 65280 depending on the
57 ;; display system. So we use a white conversion to get the max value.
58 (let ((valmax (float (car (color-values "#ffffff")))))
59 (mapcar (lambda (x) (/ x valmax)) (color-values color frame))))
60
61 (defun color-rgb-to-hex (red green blue)
62 "Return hexadecimal notation for the color RED GREEN BLUE.
63 RED GREEN BLUE must be numbers between 0.0 and 1.0 inclusive."
64 (format "#%02x%02x%02x"
65 (* red 255) (* green 255) (* blue 255)))
66
67 (defun color-complement (color-name)
68 "Return the color that is the complement of COLOR-NAME.
69 COLOR-NAME should be a string naming a color (e.g. \"white\"), or
70 a string specifying a color's RGB components (e.g. \"#ff12ec\")."
71 (let ((color (color-name-to-rgb color-name)))
72 (list (- 1.0 (car color))
73 (- 1.0 (cadr color))
74 (- 1.0 (caddr color)))))
75
76 (defun color-gradient (start stop step-number)
77 "Return a list with STEP-NUMBER colors from START to STOP.
78 The color list builds a color gradient starting at color START to
79 color STOP. It does not include the START and STOP color in the
80 resulting list."
81 (let* ((r (nth 0 start))
82 (g (nth 1 start))
83 (b (nth 2 start))
84 (r-step (/ (- (nth 0 stop) r) (1+ step-number)))
85 (g-step (/ (- (nth 1 stop) g) (1+ step-number)))
86 (b-step (/ (- (nth 2 stop) b) (1+ step-number)))
87 result)
88 (dotimes (_ step-number)
89 (push (list (setq r (+ r r-step))
90 (setq g (+ g g-step))
91 (setq b (+ b b-step)))
92 result))
93 (nreverse result)))
94
95 (defun color-hue-to-rgb (v1 v2 h)
96 "Compute hue from V1 and V2 H. Internally used by
97 `color-hsl-to-rgb'."
98 (cond
99 ((< h (/ 1.0 6)) (+ v1 (* (- v2 v1) h 6.0)))
100 ((< h 0.5) v2)
101 ((< h (/ 2.0 3)) (+ v1 (* (- v2 v1) (- (/ 2.0 3) h) 6.0)))
102 (t v1)))
103
104 (defun color-hsl-to-rgb (H S L)
105 "Convert H S L (HUE, SATURATION, LUMINANCE) , where HUE is in
106 radians and both SATURATION and LUMINANCE are between 0.0 and
107 1.0, inclusive to their RGB representation.
108
109 Return a list (RED, GREEN, BLUE) which each be numbers between
110 0.0 and 1.0, inclusive."
111
112 (if (= S 0.0)
113 (list L L L)
114 (let* ((m2 (if (<= L 0.5)
115 (* L (+ 1.0 S))
116 (- (+ L S) (* L S))))
117 (m1 (- (* 2.0 L) m2)))
118 (list
119 (color-hue-to-rgb m1 m2 (+ H (/ 1.0 3)))
120 (color-hue-to-rgb m1 m2 H)
121 (color-hue-to-rgb m1 m2 (- H (/ 1.0 3)))))))
122
123 (defun color-complement-hex (color)
124 "Return the color that is the complement of COLOR, in hexadecimal format."
125 (apply 'color-rgb-to-hex (color-complement color)))
126
127 (defun color-rgb-to-hsv (red green blue)
128 "Convert RED, GREEN, and BLUE color components to HSV.
129 RED, GREEN, and BLUE should each be numbers between 0.0 and 1.0,
130 inclusive. Return a list (HUE, SATURATION, VALUE), where HUE is
131 in radians and both SATURATION and VALUE are between 0.0 and 1.0,
132 inclusive."
133 (let* ((r (float red))
134 (g (float green))
135 (b (float blue))
136 (max (max r g b))
137 (min (min r g b)))
138 (if (< (- max min) 1e-8)
139 (list 0.0 0.0 0.0)
140 (list
141 (/ (* 2 float-pi
142 (cond ((and (= r g) (= g b)) 0)
143 ((and (= r max)
144 (>= g b))
145 (* 60 (/ (- g b) (- max min))))
146 ((and (= r max)
147 (< g b))
148 (+ 360 (* 60 (/ (- g b) (- max min)))))
149 ((= max g)
150 (+ 120 (* 60 (/ (- b r) (- max min)))))
151 ((= max b)
152 (+ 240 (* 60 (/ (- r g) (- max min)))))))
153 360)
154 (if (= max 0) 0 (- 1 (/ min max)))
155 (/ max 255.0)))))
156
157 (defun color-rgb-to-hsl (red green blue)
158 "Convert RED GREEN BLUE colors to their HSL representation.
159 RED, GREEN, and BLUE should each be numbers between 0.0 and 1.0,
160 inclusive.
161
162 Return a list (HUE, SATURATION, LUMINANCE), where HUE is in radians
163 and both SATURATION and LUMINANCE are between 0.0 and 1.0,
164 inclusive."
165 (let* ((r red)
166 (g green)
167 (b blue)
168 (max (max r g b))
169 (min (min r g b))
170 (delta (- max min))
171 (l (/ (+ max min) 2.0)))
172 (if (= delta 0)
173 (list 0.0 0.0 l)
174 (let* ((s (if (<= l 0.5) (/ delta (+ max min))
175 (/ delta (- 2.0 max min))))
176 (rc (/ (- max r) delta))
177 (gc (/ (- max g) delta))
178 (bc (/ (- max b) delta))
179 (h (mod
180 (/
181 (cond
182 ((= r max) (- bc gc))
183 ((= g max) (+ 2.0 rc (- bc)))
184 (t (+ 4.0 gc (- rc))))
185 6.0) 1.0)))
186 (list h s l)))))
187
188 (defun color-srgb-to-xyz (red green blue)
189 "Convert RED GREEN BLUE colors from the sRGB color space to CIE XYZ.
190 RED, BLUE and GREEN must be between 0 and 1, inclusive."
191 (let ((r (if (<= red 0.04045)
192 (/ red 12.95)
193 (expt (/ (+ red 0.055) 1.055) 2.4)))
194 (g (if (<= green 0.04045)
195 (/ green 12.95)
196 (expt (/ (+ green 0.055) 1.055) 2.4)))
197 (b (if (<= blue 0.04045)
198 (/ blue 12.95)
199 (expt (/ (+ blue 0.055) 1.055) 2.4))))
200 (list (+ (* 0.4124564 r) (* 0.3575761 g) (* 0.1804375 b))
201 (+ (* 0.21266729 r) (* 0.7151522 g) (* 0.0721750 b))
202 (+ (* 0.0193339 r) (* 0.1191920 g) (* 0.9503041 b)))))
203
204 (defun color-xyz-to-srgb (X Y Z)
205 "Convert CIE X Y Z colors to sRGB color space."
206 (let ((r (+ (* 3.2404542 X) (* -1.5371385 Y) (* -0.4985314 Z)))
207 (g (+ (* -0.9692660 X) (* 1.8760108 Y) (* 0.0415560 Z)))
208 (b (+ (* 0.0556434 X) (* -0.2040259 Y) (* 1.0572252 Z))))
209 (list (if (<= r 0.0031308)
210 (* 12.92 r)
211 (- (* 1.055 (expt r (/ 1 2.4))) 0.055))
212 (if (<= g 0.0031308)
213 (* 12.92 g)
214 (- (* 1.055 (expt g (/ 1 2.4))) 0.055))
215 (if (<= b 0.0031308)
216 (* 12.92 b)
217 (- (* 1.055 (expt b (/ 1 2.4))) 0.055)))))
218
219 (defconst color-d65-xyz '(0.950455 1.0 1.088753)
220 "D65 white point in CIE XYZ.")
221
222 (defconst color-cie-ε (/ 216 24389.0))
223 (defconst color-cie-κ (/ 24389 27.0))
224
225 (defun color-xyz-to-lab (X Y Z &optional white-point)
226 "Convert CIE XYZ to CIE L*a*b*.
227 WHITE-POINT specifies the (X Y Z) white point for the
228 conversion. If omitted or nil, use `color-d65-xyz'."
229 (pcase-let* ((`(,Xr ,Yr ,Zr) (or white-point color-d65-xyz))
230 (xr (/ X Xr))
231 (yr (/ Y Yr))
232 (zr (/ Z Zr))
233 (fx (if (> xr color-cie-ε)
234 (expt xr (/ 1 3.0))
235 (/ (+ (* color-cie-κ xr) 16) 116.0)))
236 (fy (if (> yr color-cie-ε)
237 (expt yr (/ 1 3.0))
238 (/ (+ (* color-cie-κ yr) 16) 116.0)))
239 (fz (if (> zr color-cie-ε)
240 (expt zr (/ 1 3.0))
241 (/ (+ (* color-cie-κ zr) 16) 116.0))))
242 (list
243 (- (* 116 fy) 16) ; L
244 (* 500 (- fx fy)) ; a
245 (* 200 (- fy fz))))) ; b
246
247 (defun color-lab-to-xyz (L a b &optional white-point)
248 "Convert CIE L*a*b* to CIE XYZ.
249 WHITE-POINT specifies the (X Y Z) white point for the
250 conversion. If omitted or nil, use `color-d65-xyz'."
251 (pcase-let* ((`(,Xr ,Yr ,Zr) (or white-point color-d65-xyz))
252 (fy (/ (+ L 16) 116.0))
253 (fz (- fy (/ b 200.0)))
254 (fx (+ (/ a 500.0) fy))
255 (xr (if (> (expt fx 3.0) color-cie-ε)
256 (expt fx 3.0)
257 (/ (- (* fx 116) 16) color-cie-κ)))
258 (yr (if (> L (* color-cie-κ color-cie-ε))
259 (expt (/ (+ L 16) 116.0) 3.0)
260 (/ L color-cie-κ)))
261 (zr (if (> (expt fz 3) color-cie-ε)
262 (expt fz 3.0)
263 (/ (- (* 116 fz) 16) color-cie-κ))))
264 (list (* xr Xr) ; X
265 (* yr Yr) ; Y
266 (* zr Zr)))) ; Z
267
268 (defun color-srgb-to-lab (red green blue)
269 "Convert RGB to CIE L*a*b*."
270 (apply 'color-xyz-to-lab (color-srgb-to-xyz red green blue)))
271
272 (defun color-lab-to-srgb (L a b)
273 "Convert CIE L*a*b* to RGB."
274 (apply 'color-xyz-to-srgb (color-lab-to-xyz L a b)))
275
276 (defun color-cie-de2000 (color1 color2 &optional kL kC kH)
277 "Return the CIEDE2000 color distance between COLOR1 and COLOR2.
278 Both COLOR1 and COLOR2 should be in CIE L*a*b* format, as
279 returned by `color-srgb-to-lab' or `color-xyz-to-lab'."
280 (pcase-let*
281 ((`(,L₁ ,a₁ ,b₁) color1)
282 (`(,L₂ ,a₂ ,b₂) color2)
283 (kL (or kL 1))
284 (kC (or kC 1))
285 (kH (or kH 1))
286 (C₁ (sqrt (+ (expt a₁ 2.0) (expt b₁ 2.0))))
287 (C₂ (sqrt (+ (expt a₂ 2.0) (expt b₂ 2.0))))
288 (C̄ (/ (+ C₁ C₂) 2.0))
289 (G (* 0.5 (- 1 (sqrt (/ (expt C̄ 7.0)
290 (+ (expt C̄ 7.0) (expt 25 7.0)))))))
291 (a′₁ (* (+ 1 G) a₁))
292 (a′₂ (* (+ 1 G) a₂))
293 (C′₁ (sqrt (+ (expt a′₁ 2.0) (expt b₁ 2.0))))
294 (C′₂ (sqrt (+ (expt a′₂ 2.0) (expt b₂ 2.0))))
295 (h′₁ (if (and (= b₁ 0) (= a′₁ 0))
296 0
297 (let ((v (atan b₁ a′₁)))
298 (if (< v 0)
299 (+ v (* 2 float-pi))
300 v))))
301 (h′₂ (if (and (= b₂ 0) (= a′₂ 0))
302 0
303 (let ((v (atan b₂ a′₂)))
304 (if (< v 0)
305 (+ v (* 2 float-pi))
306 v))))
307 (ΔL′ (- L₂ L₁))
308 (ΔC′ (- C′₂ C′₁))
309 (Δh′ (cond ((= (* C′₁ C′₂) 0)
310 0)
311 ((<= (abs (- h′₂ h′₁)) float-pi)
312 (- h′₂ h′₁))
313 ((> (- h′₂ h′₁) float-pi)
314 (- (- h′₂ h′₁) (* 2 float-pi)))
315 ((< (- h′₂ h′₁) (- float-pi))
316 (+ (- h′₂ h′₁) (* 2 float-pi)))))
317 (ΔH′ (* 2 (sqrt (* C′₁ C′₂)) (sin (/ Δh′ 2.0))))
318 (L̄′ (/ (+ L₁ L₂) 2.0))
319 (C̄′ (/ (+ C′₁ C′₂) 2.0))
320 (h̄′ (cond ((= (* C′₁ C′₂) 0)
321 (+ h′₁ h′₂))
322 ((<= (abs (- h′₁ h′₂)) float-pi)
323 (/ (+ h′₁ h′₂) 2.0))
324 ((< (+ h′₁ h′₂) (* 2 float-pi))
325 (/ (+ h′₁ h′₂ (* 2 float-pi)) 2.0))
326 ((>= (+ h′₁ h′₂) (* 2 float-pi))
327 (/ (+ h′₁ h′₂ (* -2 float-pi)) 2.0))))
328 (T (+ 1
329 (- (* 0.17 (cos (- h̄′ (degrees-to-radians 30)))))
330 (* 0.24 (cos (* h̄′ 2)))
331 (* 0.32 (cos (+ (* h̄′ 3) (degrees-to-radians 6))))
332 (- (* 0.20 (cos (- (* h̄′ 4) (degrees-to-radians 63)))))))
333 (Δθ (* (degrees-to-radians 30)
334 (exp (- (expt (/ (- h̄′ (degrees-to-radians 275))
335 (degrees-to-radians 25)) 2.0)))))
336 (Rc (* 2 (sqrt (/ (expt C̄′ 7.0) (+ (expt C̄′ 7.0) (expt 25.0 7.0))))))
337 (Sl (+ 1 (/ (* 0.015 (expt (- L̄′ 50) 2.0))
338 (sqrt (+ 20 (expt (- L̄′ 50) 2.0))))))
339 (Sc (+ 1 (* C̄′ 0.045)))
340 (Sh (+ 1 (* 0.015 C̄′ T)))
341 (Rt (- (* (sin (* Δθ 2)) Rc))))
342 (sqrt (+ (expt (/ ΔL′ (* Sl kL)) 2.0)
343 (expt (/ ΔC′ (* Sc kC)) 2.0)
344 (expt (/ ΔH′ (* Sh kH)) 2.0)
345 (* Rt (/ ΔC′ (* Sc kC)) (/ ΔH′ (* Sh kH)))))))
346
347 (defun color-clamp (value)
348 "Make sure VALUE is a number between 0.0 and 1.0 inclusive."
349 (min 1.0 (max 0.0 value)))
350
351 (defun color-saturate-hsl (H S L percent)
352 "Return a color PERCENT more saturated than the one defined in
353 H S L color-space.
354
355 Return a list (HUE, SATURATION, LUMINANCE), where HUE is in radians
356 and both SATURATION and LUMINANCE are between 0.0 and 1.0,
357 inclusive."
358 (list H (color-clamp (+ S (/ percent 100.0))) L))
359
360 (defun color-saturate-name (name percent)
361 "Short hand to saturate COLOR by PERCENT.
362
363 See `color-saturate-hsl'."
364 (apply 'color-rgb-to-hex
365 (apply 'color-hsl-to-rgb
366 (apply 'color-saturate-hsl
367 (append
368 (apply 'color-rgb-to-hsl
369 (color-name-to-rgb name))
370 (list percent))))))
371
372 (defun color-desaturate-hsl (H S L percent)
373 "Return a color PERCENT less saturated than the one defined in
374 H S L color-space.
375
376 Return a list (HUE, SATURATION, LUMINANCE), where HUE is in radians
377 and both SATURATION and LUMINANCE are between 0.0 and 1.0,
378 inclusive."
379 (color-saturate-hsl H S L (- percent)))
380
381 (defun color-desaturate-name (name percent)
382 "Short hand to desaturate COLOR by PERCENT.
383
384 See `color-desaturate-hsl'."
385 (color-saturate-name name (- percent)))
386
387 (defun color-lighten-hsl (H S L percent)
388 "Return a color PERCENT lighter than the one defined in
389 H S L color-space.
390
391 Return a list (HUE, SATURATION, LUMINANCE), where HUE is in radians
392 and both SATURATION and LUMINANCE are between 0.0 and 1.0,
393 inclusive."
394 (list H S (color-clamp (+ L (/ percent 100.0)))))
395
396 (defun color-lighten-name (name percent)
397 "Short hand to saturate COLOR by PERCENT.
398
399 See `color-lighten-hsl'."
400 (apply 'color-rgb-to-hex
401 (apply 'color-hsl-to-rgb
402 (apply 'color-lighten-hsl
403 (append
404 (apply 'color-rgb-to-hsl
405 (color-name-to-rgb name))
406 (list percent))))))
407
408 (defun color-darken-hsl (H S L percent)
409 "Return a color PERCENT darker than the one defined in
410 H S L color-space.
411
412 Return a list (HUE, SATURATION, LUMINANCE), where HUE is in radians
413 and both SATURATION and LUMINANCE are between 0.0 and 1.0,
414 inclusive."
415 (color-lighten-hsl H S L (- percent)))
416
417 (defun color-darken-name (name percent)
418 "Short hand to saturate COLOR by PERCENT.
419
420 See `color-darken-hsl'."
421 (color-lighten-name name (- percent)))
422
423 (provide 'color)
424
425 ;;; color.el ends here