lisp/color.el

   1 ;;; color.el --- Color manipulation laboratory routines -*- coding: utf-8; -*-
   2
   3 ;; Copyright (C) 2010-2011 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 (eval-when-compile
  30   (require 'cl))
  31
  32 ;; Emacs < 23.3
  33 (eval-and-compile
  34   (unless (boundp 'float-pi)
  35     (defconst float-pi (* 4 (atan 1)) "The value of Pi (3.1415926...).")))
  36
  37 (defun color-rgb->hex  (red green blue)
  38   "Return hexadecimal notation for RED GREEN BLUE color.
  39 RED GREEN BLUE must be values between 0 and 1 inclusively."
  40   (format "#%02x%02x%02x"
  41           (* red 255) (* green 255) (* blue 255)))
  42
  43 (defun color-complement (color)
  44   "Return the color that is the complement of COLOR."
  45   (let ((color (color-rgb->normalize color)))
  46     (list (- 1.0 (car color))
  47           (- 1.0 (cadr color))
  48           (- 1.0 (caddr color)))))
  49
  50 (defun color-complement-hex (color)
  51   "Return the color that is the complement of COLOR, in hexadecimal format."
  52   (apply 'color-rgb->hex (color-complement color)))
  53
  54 (defun color-rgb->hsv (red green blue)
  55   "Convert RED GREEN BLUE values to HSV representation.
  56 Hue is in radians. Saturation and values are between 0 and 1
  57 inclusively."
  58    (let* ((r (float red))
  59          (g (float green))
  60          (b (float blue))
  61          (max (max r g b))
  62          (min (min r g b)))
  63      (list
  64       (/ (* 2 float-pi
  65             (cond ((and (= r g) (= g b)) 0)
  66                   ((and (= r max)
  67                         (>= g b))
  68                    (* 60 (/ (- g b) (- max min))))
  69                   ((and (= r max)
  70                         (< g b))
  71                    (+ 360 (* 60 (/ (- g b) (- max min)))))
  72                   ((= max g)
  73                    (+ 120 (* 60 (/ (- b r) (- max min)))))
  74                   ((= max b)
  75                        (+ 240 (* 60 (/ (- r g) (- max min)))))))
  76          360)
  77       (if (= max 0)
  78           0
  79         (- 1 (/ min max)))
  80       (/ max 255.0))))
  81
  82 (defun color-rgb->hsl (red green blue)
  83   "Convert RED GREEN BLUE colors to their HSL representation.
  84 RED, GREEN and BLUE must be between 0 and 1 inclusively."
  85   (let* ((r red)
  86          (g green)
  87          (b blue)
  88          (max (max r g b))
  89          (min (min r g b))
  90          (delta (- max min))
  91          (l (/ (+ max min) 2.0)))
  92     (list
  93      (if (= max min)
  94          0
  95        (* 2 float-pi
  96           (/ (cond ((= max r)
  97                     (+ (/ (- g b) delta) (if (< g b) 6 0)))
  98                    ((= max g)
  99                  (+ (/ (- b r) delta) 2))
 100                    (t
 101                     (+ (/ (- r g) delta) 4)))
 102              6)))
 103      (if (= max min)
 104          0
 105        (if (> l 0.5)
 106            (/ delta (- 2 (+ max min)))
 107          (/ delta (+ max min))))
 108      l)))
 109
 110 (defun color-srgb->xyz (red green blue)
 111   "Converts RED GREEN BLUE colors from the sRGB color space to CIE XYZ.
 112 RED, BLUE and GREEN must be between 0 and 1 inclusively."
 113   (let ((r (if (<= red 0.04045)
 114                (/ red 12.95)
 115              (expt (/ (+ red 0.055) 1.055) 2.4)))
 116         (g (if (<= green 0.04045)
 117                (/ green 12.95)
 118              (expt (/ (+ green 0.055) 1.055) 2.4)))
 119         (b (if (<= blue 0.04045)
 120                (/ blue 12.95)
 121              (expt (/ (+ blue 0.055) 1.055) 2.4))))
 122     (list (+ (* 0.4124564 r) (* 0.3575761 g) (* 0.1804375 b))
 123           (+ (* 0.21266729 r) (* 0.7151522 g) (* 0.0721750 b))
 124           (+ (* 0.0193339 r) (* 0.1191920 g) (* 0.9503041 b)))))
 125
 126 (defun color-xyz->srgb (X Y Z)
 127   "Converts CIE X Y Z colors to sRGB color space."
 128   (let ((r (+ (* 3.2404542 X) (* -1.5371385 Y) (* -0.4985314 Z)))
 129         (g (+ (* -0.9692660 X) (* 1.8760108 Y) (* 0.0415560 Z)))
 130         (b (+ (* 0.0556434 X) (* -0.2040259 Y) (* 1.0572252 Z))))
 131     (list (if (<= r 0.0031308)
 132               (* 12.92 r)
 133             (- (* 1.055 (expt r (/ 1 2.4))) 0.055))
 134           (if (<= g 0.0031308)
 135               (* 12.92 g)
 136             (- (* 1.055 (expt g (/ 1 2.4))) 0.055))
 137           (if (<= b 0.0031308)
 138               (* 12.92 b)
 139             (- (* 1.055 (expt b (/ 1 2.4))) 0.055)))))
 140
 141 (defconst color-d65-xyz '(0.950455 1.0 1.088753)
 142   "D65 white point in CIE XYZ.")
 143
 144 (defconst color-cie-ε (/ 216 24389.0))
 145 (defconst color-cie-κ (/ 24389 27.0))
 146
 147 (defun color-xyz->lab (X Y Z &optional white-point)
 148   "Converts CIE XYZ to CIE L*a*b*.
 149 WHITE-POINT can be specified as (X Y Z) white point to use. If
 150 none is set, `color-d65-xyz' is used."
 151   (destructuring-bind (Xr Yr Zr) (or white-point color-d65-xyz)
 152       (let* ((xr (/ X Xr))
 153              (yr (/ Y Yr))
 154              (zr (/ Z Zr))
 155              (fx (if (> xr color-cie-ε)
 156                      (expt xr (/ 1 3.0))
 157                    (/ (+ (* color-cie-κ xr) 16) 116.0)))
 158              (fy (if (> yr color-cie-ε)
 159                      (expt yr (/ 1 3.0))
 160                    (/ (+ (* color-cie-κ yr) 16) 116.0)))
 161              (fz (if (> zr color-cie-ε)
 162                      (expt zr (/ 1 3.0))
 163                    (/ (+ (* color-cie-κ zr) 16) 116.0))))
 164         (list
 165          (- (* 116 fy) 16)                  ; L
 166          (* 500 (- fx fy))                  ; a
 167          (* 200 (- fy fz))))))              ; b
 168
 169 (defun color-lab->xyz (L a b &optional white-point)
 170   "Converts CIE L*a*b* to CIE XYZ.
 171 WHITE-POINT can be specified as (X Y Z) white point to use. If
 172 none is set, `color-d65-xyz' is used."
 173   (destructuring-bind (Xr Yr Zr) (or white-point color-d65-xyz)
 174       (let* ((fy (/ (+ L 16) 116.0))
 175              (fz (- fy (/ b 200.0)))
 176              (fx (+ (/ a 500.0) fy))
 177              (xr (if (> (expt fx 3.0) color-cie-ε)
 178                      (expt fx 3.0)
 179                (/ (- (* fx 116) 16) color-cie-κ)))
 180              (yr (if (> L (* color-cie-κ color-cie-ε))
 181                      (expt (/ (+ L 16) 116.0) 3.0)
 182                    (/ L color-cie-κ)))
 183              (zr (if (> (expt fz 3) color-cie-ε)
 184                      (expt fz 3.0)
 185                    (/ (- (* 116 fz) 16) color-cie-κ))))
 186         (list (* xr Xr)                 ; X
 187               (* yr Yr)                 ; Y
 188               (* zr Zr)))))             ; Z
 189
 190 (defun color-srgb->lab (red green blue)
 191   "Converts RGB to CIE L*a*b*."
 192   (apply 'color-xyz->lab (color-srgb->xyz red green blue)))
 193
 194 (defun color-rgb->normalize (color)
 195   "Normalize a RGB color to values between 0 and 1 inclusively."
 196   (mapcar (lambda (x) (/ x 65535.0)) (x-color-values color)))
 197
 198 (defun color-lab->srgb (L a b)
 199   "Converts CIE L*a*b* to RGB."
 200   (apply 'color-xyz->srgb (color-lab->xyz L a b)))
 201
 202 (defun color-cie-de2000 (color1 color2 &optional kL kC kH)
 203   "Computes the CIEDE2000 color distance between COLOR1 and COLOR2.
 204 Colors must be in CIE L*a*b* format."
 205   (destructuring-bind (L₁ a₁ b₁) color1
 206     (destructuring-bind (L₂ a₂ b₂) color2
 207       (let* ((kL (or kL 1))
 208              (kC (or kC 1))
 209              (kH (or kH 1))
 210              (C₁ (sqrt (+ (expt a₁ 2.0) (expt b₁ 2.0))))
 211              (C₂ (sqrt (+ (expt a₂ 2.0) (expt b₂ 2.0))))
 212              (C̄ (/ (+ C₁ C₂) 2.0))
 213              (G (* 0.5 (- 1 (sqrt (/ (expt C̄ 7.0) (+ (expt C̄ 7.0) (expt 25 7.0)))))))
 214              (a′₁ (* (+ 1 G) a₁))
 215              (a′₂ (* (+ 1 G) a₂))
 216              (C′₁ (sqrt (+ (expt a′₁ 2.0) (expt b₁ 2.0))))
 217              (C′₂ (sqrt (+ (expt a′₂ 2.0) (expt b₂ 2.0))))
 218              (h′₁ (if (and (= b₁ 0) (= a′₁ 0))
 219                       0
 220                     (let ((v (atan b₁ a′₁)))
 221                       (if (< v 0)
 222                           (+ v (* 2 float-pi))
 223                         v))))
 224              (h′₂ (if (and (= b₂ 0) (= a′₂ 0))
 225                       0
 226                     (let ((v (atan b₂ a′₂)))
 227                       (if (< v 0)
 228                           (+ v (* 2 float-pi))
 229                         v))))
 230              (ΔL′ (- L₂ L₁))
 231              (ΔC′ (- C′₂ C′₁))
 232              (Δh′ (cond ((= (* C′₁ C′₂) 0)
 233                          0)
 234                         ((<= (abs (- h′₂ h′₁)) float-pi)
 235                          (- h′₂ h′₁))
 236                         ((> (- h′₂ h′₁) float-pi)
 237                          (- (- h′₂ h′₁) (* 2 float-pi)))
 238                         ((< (- h′₂ h′₁) (- float-pi))
 239                          (+ (- h′₂ h′₁) (* 2 float-pi)))))
 240              (ΔH′ (* 2 (sqrt (* C′₁ C′₂)) (sin (/ Δh′ 2.0))))
 241              (L̄′ (/ (+ L₁ L₂) 2.0))
 242              (C̄′ (/ (+ C′₁ C′₂) 2.0))
 243              (h̄′ (cond ((= (* C′₁ C′₂) 0)
 244                         (+ h′₁ h′₂))
 245                        ((<= (abs (- h′₁ h′₂)) float-pi)
 246                         (/ (+ h′₁ h′₂) 2.0))
 247                        ((< (+ h′₁ h′₂) (* 2 float-pi))
 248                         (/ (+ h′₁ h′₂ (* 2 float-pi)) 2.0))
 249                        ((>= (+ h′₁ h′₂) (* 2 float-pi))
 250                         (/ (+ h′₁ h′₂ (* -2 float-pi)) 2.0))))
 251              (T (+ 1
 252                    (- (* 0.17 (cos (- h̄′ (degrees-to-radians 30)))))
 253                    (* 0.24 (cos (* h̄′ 2)))
 254                    (* 0.32 (cos (+ (* h̄′ 3) (degrees-to-radians 6))))
 255                    (- (* 0.20 (cos (- (* h̄′ 4) (degrees-to-radians 63)))))))
 256              (Δθ (* (degrees-to-radians 30) (exp (- (expt (/ (- h̄′ (degrees-to-radians 275)) (degrees-to-radians 25)) 2.0)))))
 257              (Rc (* 2 (sqrt (/ (expt C̄′ 7.0) (+ (expt C̄′ 7.0) (expt 25.0 7.0))))))
 258              (Sl (+ 1 (/ (* 0.015 (expt (- L̄′ 50) 2.0)) (sqrt (+ 20 (expt (- L̄′ 50) 2.0))))))
 259              (Sc (+ 1 (* C̄′ 0.045)))
 260              (Sh (+ 1 (* 0.015 C̄′ T)))
 261              (Rt (- (* (sin (* Δθ 2)) Rc))))
 262         (sqrt (+ (expt (/ ΔL′ (* Sl kL)) 2.0)
 263                  (expt (/ ΔC′ (* Sc kC)) 2.0)
 264                  (expt (/ ΔH′ (* Sh kH)) 2.0)
 265                  (* Rt (/ ΔC′ (* Sc kC)) (/ ΔH′ (* Sh kH)))))))))
 266
 267 (provide 'color)
 268
 269 ;;; color.el ends here