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1 | ;;; color-lab.el --- Color manipulation laboratory routines |
2 | ||
3 | ;; Copyright (C) 2010 Free Software Foundation, Inc. | |
4 | ||
5 | ;; Author: Julien Danjou <julien@danjou.info> | |
6 | ;; Keywords: html | |
7 | ||
8 | ;; This file is part of GNU Emacs. | |
9 | ||
10 | ;; GNU Emacs is free software: you can redistribute it and/or modify | |
11 | ;; it under the terms of the GNU General Public License as published by | |
12 | ;; the Free Software Foundation, either version 3 of the License, or | |
13 | ;; (at your option) any later version. | |
14 | ||
15 | ;; GNU Emacs is distributed in the hope that it will be useful, | |
16 | ;; but WITHOUT ANY WARRANTY; without even the implied warranty of | |
17 | ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
18 | ;; GNU General Public License for more details. | |
19 | ||
20 | ;; You should have received a copy of the GNU General Public License | |
21 | ;; along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>. | |
22 | ||
23 | ;;; Commentary: | |
24 | ||
25 | ;; This package provides color manipulation functions. | |
26 | ||
27 | ;;; Code: | |
28 | ||
29 | (defun rgb->hsv (red green blue) | |
30 | "Convert RED GREEN BLUE values to HSV representation. | |
31 | Hue is in radian. Saturation and values are between 0 and 1." | |
32 | (let* ((r (float red)) | |
33 | (g (float green)) | |
34 | (b (float blue)) | |
35 | (max (max r g b)) | |
36 | (min (min r g b))) | |
37 | (list | |
38 | (/ (* 2 float-pi | |
39 | (cond ((and (= r g) (= g b)) 0) | |
40 | ((and (= r max) | |
41 | (>= g b)) | |
42 | (* 60 (/ (- g b) (- max min)))) | |
43 | ((and (= r max) | |
44 | (< g b)) | |
45 | (+ 360 (* 60 (/ (- g b) (- max min))))) | |
46 | ((= max g) | |
47 | (+ 120 (* 60 (/ (- b r) (- max min))))) | |
48 | ((= max b) | |
49 | (+ 240 (* 60 (/ (- r g) (- max min))))))) | |
50 | 360) | |
51 | (if (= max 0) | |
52 | 0 | |
53 | (- 1 (/ min max))) | |
54 | (/ max 255.0)))) | |
55 | ||
56 | (defun rgb->hsl (red green blue) | |
57 | "Convert RED GREEN BLUE colors to their HSL representation. | |
58 | RED, GREEN and BLUE must be between 0 and 255." | |
59 | (let* ((r (/ red 255.0)) | |
60 | (g (/ green 255.0)) | |
61 | (b (/ blue 255.0)) | |
62 | (max (max r g b)) | |
63 | (min (min r g b)) | |
64 | (delta (- max min)) | |
65 | (l (/ (+ max min) 2.0))) | |
66 | (list | |
67 | (if (= max min) | |
68 | 0 | |
69 | (* 2 float-pi | |
70 | (/ (cond ((= max r) | |
71 | (+ (/ (- g b) delta) (if (< g b) 6 0))) | |
72 | ((= max g) | |
73 | (+ (/ (- b r) delta) 2)) | |
74 | (t | |
75 | (+ (/ (- r g) delta) 4))) | |
76 | 6))) | |
77 | (if (= max min) | |
78 | 0 | |
79 | (if (> l 0.5) | |
80 | (/ delta (- 2 (+ max min))) | |
81 | (/ delta (+ max min)))) | |
82 | l))) | |
83 | ||
84 | (defun rgb->xyz (red green blue) | |
85 | "Converts RED GREEN BLUE colors to CIE XYZ representation. | |
86 | RED, BLUE and GREEN must be between 0 and 1." | |
87 | (let ((r (if (<= red 0.04045) | |
88 | (/ red 12.95) | |
89 | (expt (/ (+ red 0.055) 1.055) 2.4))) | |
90 | (g (if (<= green 0.04045) | |
91 | (/ green 12.95) | |
92 | (expt (/ (+ green 0.055) 1.055) 2.4))) | |
93 | (b (if (<= blue 0.04045) | |
94 | (/ blue 12.95) | |
95 | (expt (/ (+ blue 0.055) 1.055) 2.4)))) | |
96 | (list (+ (* 0.4124564 r) (* 0.3575761 g) (* 0.1804375 b)) | |
97 | (+ (* 0.21266729 r) (* 0.7151522 g) (* 0.0721750 b)) | |
98 | (+ (* 0.0193339 r) (* 0.1191920 g) (* 0.9503041 b))))) | |
99 | ||
100 | (defun xyz->rgb (X Y Z) | |
101 | "Converts CIE XYZ colors to RGB." | |
102 | (let ((r (+ (* 3.2404542 X) (* -1.5371385 Y) (* -0.4985314 Z))) | |
103 | (g (+ (* -0.9692660 X) (* 1.8760108 Y) (* 0.0415560 Z))) | |
104 | (b (+ (* 0.0556434 X) (* -0.2040259 Y) (* 1.0572252 Z)))) | |
105 | (list (if (<= r 0.0031308) | |
106 | (* 12.92 r) | |
107 | (- (* 1.055 (expt r (/ 1 2.4))) 0.055)) | |
108 | (if (<= g 0.0031308) | |
109 | (* 12.92 g) | |
110 | (- (* 1.055 (expt g (/ 1 2.4))) 0.055)) | |
111 | (if (<= b 0.0031308) | |
112 | (* 12.92 b) | |
113 | (- (* 1.055 (expt b (/ 1 2.4))) 0.055))))) | |
114 | ||
115 | (defconst color-lab-d65-xyz '(0.950455 1.0 1.088753) | |
116 | "D65 white point in CIE XYZ.") | |
117 | ||
118 | (defconst color-lab-ε (/ 216 24389.0)) | |
119 | (defconst color-lab-κ (/ 24389 27.0)) | |
120 | ||
121 | (defun xyz->lab (X Y Z &optional white-point) | |
122 | "Converts CIE XYZ to CIE L*a*b*. | |
123 | WHITE-POINT can be specified as (X Y Z) white point to use. If | |
124 | none is set, `color-lab-d65-xyz' is used." | |
125 | (destructuring-bind (Xr Yr Zr) (or white-point color-lab-d65-xyz) | |
126 | (let* ((xr (/ X Xr)) | |
127 | (yr (/ Y Yr)) | |
128 | (zr (/ Z Zr)) | |
129 | (fx (if (> xr color-lab-ε) | |
130 | (expt xr (/ 1 3.0)) | |
131 | (/ (+ (* color-lab-κ xr) 16) 116.0))) | |
132 | (fy (if (> yr color-lab-ε) | |
133 | (expt yr (/ 1 3.0)) | |
134 | (/ (+ (* color-lab-κ yr) 16) 116.0))) | |
135 | (fz (if (> zr color-lab-ε) | |
136 | (expt zr (/ 1 3.0)) | |
137 | (/ (+ (* color-lab-κ zr) 16) 116.0)))) | |
138 | (list | |
139 | (- (* 116 fy) 16) ; L | |
140 | (* 500 (- fx fy)) ; a | |
141 | (* 200 (- fy fz)))))) ; b | |
142 | ||
143 | (defun lab->xyz (L a b &optional white-point) | |
144 | "Converts CIE L*a*b* to CIE XYZ. | |
145 | WHITE-POINT can be specified as (X Y Z) white point to use. If | |
146 | none is set, `color-lab-d65-xyz' is used." | |
147 | (destructuring-bind (Xr Yr Zr) (or white-point color-lab-d65-xyz) | |
148 | (let* ((fy (/ (+ L 16) 116.0)) | |
149 | (fz (- fy (/ b 200.0))) | |
150 | (fx (+ (/ a 500.0) fy)) | |
151 | (xr (if (> (expt fx 3) color-lab-ε) | |
152 | (expt fx 3) | |
153 | (/ (- (* fx 116) 16) color-lab-κ))) | |
154 | (yr (if (> L (* color-lab-κ color-lab-ε)) | |
155 | (expt (/ (+ L 16) 116.0) 3) | |
156 | (/ L color-lab-κ))) | |
157 | (zr (if (> (expt fz 3) color-lab-ε) | |
158 | (expt fz 3) | |
159 | (/ (- (* 116 fz) 16) color-lab-κ)))) | |
160 | (list (* xr Xr) ; X | |
161 | (* yr Yr) ; Y | |
162 | (* zr Zr))))) ; Z | |
163 | ||
164 | (defun rgb->lab (red green blue) | |
165 | "Converts RGB to CIE L*a*b*." | |
166 | (apply 'xyz->lab (rgb->xyz red green blue))) | |
167 | ||
168 | (defun rgb->normalize (color) | |
169 | "Normalize a RGB color to values between [0,1]." | |
170 | (mapcar (lambda (x) (/ x 65535.0)) (x-color-values color))) | |
171 | ||
172 | (defun lab->rgb (L a b) | |
173 | "Converts CIE L*a*b* to RGB." | |
174 | (apply 'xyz->rgb (lab->xyz L a b))) | |
175 | ||
176 | (defun color-lab-ciede2000 (color1 color2 &optional kL kC kH) | |
177 | "Computes the CIEDE2000 color distance between COLOR1 and COLOR2. | |
178 | Colors must be in CIE L*a*b* format." | |
179 | (destructuring-bind (L₁ a₁ b₁) color1 | |
180 | (destructuring-bind (L₂ a₂ b₂) color2 | |
181 | (let* ((kL (or kL 1)) | |
182 | (kC (or kC 1)) | |
183 | (kH (or kH 1)) | |
184 | (C₁ (sqrt (+ (expt a₁ 2) (expt b₁ 2)))) | |
185 | (C₂ (sqrt (+ (expt a₂ 2) (expt b₂ 2)))) | |
186 | (C̄ (/ (+ C₁ C₂) 2.0)) | |
187 | (G (* 0.5 (- 1 (sqrt (/ (expt C̄ 7) (+ (expt C̄ 7) (expt 25 7))))))) | |
188 | (a′₁ (* (+ 1 G) a₁)) | |
189 | (a′₂ (* (+ 1 G) a₂)) | |
190 | (C′₁ (sqrt (+ (expt a′₁ 2) (expt b₁ 2)))) | |
191 | (C′₂ (sqrt (+ (expt a′₂ 2) (expt b₂ 2)))) | |
192 | (h′₁ (if (and (= b₁ 0) (= a′₁ 0)) | |
193 | 0 | |
194 | (let ((v (atan b₁ a′₁))) | |
195 | (if (< v 0) | |
196 | (+ v (* 2 float-pi)) | |
197 | v)))) | |
198 | (h′₂ (if (and (= b₂ 0) (= a′₂ 0)) | |
199 | 0 | |
200 | (let ((v (atan b₂ a′₂))) | |
201 | (if (< v 0) | |
202 | (+ v (* 2 float-pi)) | |
203 | v)))) | |
204 | (ΔL′ (- L₂ L₁)) | |
205 | (ΔC′ (- C′₂ C′₁)) | |
206 | (Δh′ (cond ((= (* C′₁ C′₂) 0) | |
207 | 0) | |
208 | ((<= (abs (- h′₂ h′₁)) float-pi) | |
209 | (- h′₂ h′₁)) | |
210 | ((> (- h′₂ h′₁) float-pi) | |
211 | (- (- h′₂ h′₁) (* 2 float-pi))) | |
212 | ((< (- h′₂ h′₁) (- float-pi)) | |
213 | (+ (- h′₂ h′₁) (* 2 float-pi))))) | |
214 | (ΔH′ (* 2 (sqrt (* C′₁ C′₂)) (sin (/ Δh′ 2.0)))) | |
215 | (L̄′ (/ (+ L₁ L₂) 2.0)) | |
216 | (C̄′ (/ (+ C′₁ C′₂) 2.0)) | |
217 | (h̄′ (cond ((= (* C′₁ C′₂) 0) | |
218 | (+ h′₁ h′₂)) | |
219 | ((<= (abs (- h′₁ h′₂)) float-pi) | |
220 | (/ (+ h′₁ h′₂) 2.0)) | |
221 | ((< (+ h′₁ h′₂) (* 2 float-pi)) | |
222 | (/ (+ h′₁ h′₂ (* 2 float-pi)) 2.0)) | |
223 | ((>= (+ h′₁ h′₂) (* 2 float-pi)) | |
224 | (/ (+ h′₁ h′₂ (* -2 float-pi)) 2.0)))) | |
225 | (T (+ 1 | |
226 | (- (* 0.17 (cos (- h̄′ (degrees-to-radians 30))))) | |
227 | (* 0.24 (cos (* h̄′ 2))) | |
228 | (* 0.32 (cos (+ (* h̄′ 3) (degrees-to-radians 6)))) | |
229 | (- (* 0.20 (cos (- (* h̄′ 4) (degrees-to-radians 63))))))) | |
230 | (Δθ (* (degrees-to-radians 30) (exp (- (expt (/ (- h̄′ (degrees-to-radians 275)) (degrees-to-radians 25)) 2))))) | |
231 | (Rc (* 2 (sqrt (/ (expt C̄′ 7) (+ (expt C̄′ 7) (expt 25 7)))))) | |
232 | (Sl (+ 1 (/ (* 0.015 (expt (- L̄′ 50) 2)) (sqrt (+ 20 (expt (- L̄′ 50) 2)))))) | |
233 | (Sc (+ 1 (* C̄′ 0.045))) | |
234 | (Sh (+ 1 (* 0.015 C̄′ T))) | |
235 | (Rt (- (* (sin (* Δθ 2)) Rc)))) | |
236 | (sqrt (+ (expt (/ ΔL′ (* Sl kL)) 2) | |
237 | (expt (/ ΔC′ (* Sc kC)) 2) | |
238 | (expt (/ ΔH′ (* Sh kH)) 2) | |
239 | (* Rt (/ ΔC′ (* Sc kC)) (/ ΔH′ (* Sh kH))))))))) | |
240 | ||
241 | (provide 'color-lab) |