001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017package org.apache.commons.imaging.color;
018
019public final class ColorConversions {
020
021    // White reference
022    /** See: https://en.wikipedia.org/wiki/CIELAB_color_space#From_CIEXYZ_to_CIELAB[10] */
023    private static final double REF_X = 95.047; // Observer= 2°, Illuminant= D65
024
025    /** See: https://en.wikipedia.org/wiki/CIELAB_color_space#From_CIEXYZ_to_CIELAB[10] */
026    private static final double REF_Y = 100.000;
027
028    /** See: https://en.wikipedia.org/wiki/CIELAB_color_space#From_CIEXYZ_to_CIELAB[10] */
029    private static final double REF_Z = 108.883;
030
031    /** See: https://en.wikipedia.org/wiki/CIELAB_color_space#From_CIEXYZ_to_CIELAB[10] */
032    private static final double XYZ_m = 7.787037; // match in slope. Note commonly seen 7.787 gives worse results
033
034    /** See: https://en.wikipedia.org/wiki/CIELAB_color_space#From_CIEXYZ_to_CIELAB[10] */
035    private static final double XYZ_t0 = 0.008856;
036
037    public static int convertCieLabToArgbTest(final int cieL, final int cieA, final int cieB) {
038        final double x;
039        final double y;
040        final double z;
041        {
042
043            double varY = (cieL * 100.0 / 255.0 + 16.0) / 116.0;
044            double varX = cieA / 500.0 + varY;
045            double varZ = varY - cieB / 200.0;
046
047            varX = unPivotXyz(varX);
048            varY = unPivotXyz(varY);
049            varZ = unPivotXyz(varZ);
050
051            x = REF_X * varX; // REF_X = 95.047 Observer= 2°, Illuminant= D65
052            y = REF_Y * varY; // REF_Y = 100.000
053            z = REF_Z * varZ; // REF_Z = 108.883
054
055        }
056
057        final double r;
058        final double g;
059        final double b;
060        {
061            final double varX = x / 100; // X = From 0 to REF_X
062            final double varY = y / 100; // Y = From 0 to REF_Y
063            final double varZ = z / 100; // Z = From 0 to REF_Y
064
065            double varR = varX * 3.2406 + varY * -1.5372 + varZ * -0.4986;
066            double varG = varX * -0.9689 + varY * 1.8758 + varZ * 0.0415;
067            double varB = varX * 0.0557 + varY * -0.2040 + varZ * 1.0570;
068
069            varR = pivotRgb(varR);
070            varG = pivotRgb(varG);
071            varB = pivotRgb(varB);
072
073            r = varR * 255;
074            g = varG * 255;
075            b = varB * 255;
076        }
077
078        return convertRgbToRgb(r, g, b);
079    }
080
081    public static ColorCieLch convertCieLabToCieLch(final ColorCieLab cielab) {
082        return convertCieLabToCieLch(cielab.l, cielab.a, cielab.b);
083    }
084
085    public static ColorCieLch convertCieLabToCieLch(final double l, final double a, final double b) {
086        // atan2(y,x) returns atan(y/x)
087        final double atanba = Math.atan2(b, a); // Quadrant by signs
088
089        final double h = atanba > 0 //
090                ? Math.toDegrees(atanba) //
091                : Math.toDegrees(atanba) + 360;
092
093        // L = L;
094        final double C = Math.sqrt(square(a) + square(b));
095
096        return new ColorCieLch(l, C, h);
097    }
098
099    public static ColorDin99Lab convertCieLabToDin99bLab(final ColorCieLab cie) {
100        return convertCieLabToDin99bLab(cie.l, cie.a, cie.b);
101    }
102
103    public static ColorDin99Lab convertCieLabToDin99bLab(final double l, final double a, final double b) {
104        final double fac1 = 100.0 / Math.log(129.0 / 50.0); // = 105.51
105        final double kE = 1.0; // brightness factor, 1.0 for CIE reference conditions
106        final double kCH = 1.0; // chroma and hue factor, 1.0 for CIE reference conditions
107        final double ang = Math.toRadians(16.0);
108
109        final double l99 = kE * fac1 * Math.log(1. + 0.0158 * l);
110        double a99 = 0.0;
111        double b99 = 0.0;
112        if (a != 0.0 || b != 0.0) {
113            final double e = a * Math.cos(ang) + b * Math.sin(ang);
114            final double f = 0.7 * (b * Math.cos(ang) - a * Math.sin(ang));
115            final double G = Math.sqrt(e * e + f * f);
116            if (G != 0.) {
117                final double k = Math.log(1. + 0.045 * G) / (0.045 * kCH * kE * G);
118                a99 = k * e;
119                b99 = k * f;
120            }
121        }
122        return new ColorDin99Lab(l99, a99, b99);
123    }
124
125    /**
126     * DIN99o.
127     *
128     * @param cie CIE color.
129     * @return CIELab colors converted to DIN99oLab color space.
130     * @see <a href=
131     *      "https://de.wikipedia.org/w/index.php?title=Diskussion:DIN99-Farbraum">https://de.wikipedia.org/w/index.php?title=Diskussion:DIN99-Farbraum</a>
132     */
133    public static ColorDin99Lab convertCieLabToDin99oLab(final ColorCieLab cie) {
134        return convertCieLabToDin99oLab(cie.l, cie.a, cie.b);
135    }
136
137    /**
138     * DIN99o.
139     *
140     * @param l lightness of color.
141     * @param a position between red and green.
142     * @param b position between yellow and blue.
143     * @return CIBELab colors converted to DIN99oLab color space.
144     * @see <a href=
145     *      "https://de.wikipedia.org/w/index.php?title=Diskussion:DIN99-Farbraum">https://de.wikipedia.org/w/index.php?title=Diskussion:DIN99-Farbraum</a>
146     */
147    public static ColorDin99Lab convertCieLabToDin99oLab(final double l, final double a, final double b) {
148        final double kE = 1.0; // brightness factor, 1.0 for CIE reference conditions
149        final double kCH = 1.0; // chroma and hue factor, 1.0 for CIE reference conditions
150        final double fac1 = 100.0 / Math.log(139.0 / 100.0); // L99 scaling factor = 303.67100547050995
151        final double ang = Math.toRadians(26.0);
152
153        final double l99o = fac1 / kE * Math.log(1 + 0.0039 * l); // Lightness correction kE
154        double a99o = 0.0;
155        double b99o = 0.0;
156        if (a != 0.0 || b != 0.0) {
157            final double eo = a * Math.cos(ang) + b * Math.sin(ang); // a stretching
158            final double fo = 0.83 * (b * Math.cos(ang) - a * Math.sin(ang)); // b rotation/stretching
159            final double Go = Math.sqrt(eo * eo + fo * fo); // chroma
160            final double C99o = Math.log(1.0 + 0.075 * Go) / (0.0435 * kCH * kE); // factor for chroma compression and viewing conditions
161            final double heofo = Math.atan2(fo, eo); // arctan in four quadrants
162            final double h99o = heofo + ang; // hue rotation
163            a99o = C99o * Math.cos(h99o);
164            b99o = C99o * Math.sin(h99o);
165        }
166        return new ColorDin99Lab(l99o, a99o, b99o);
167    }
168
169    public static ColorXyz convertCieLabToXyz(final ColorCieLab cielab) {
170        return convertCieLabToXyz(cielab.l, cielab.a, cielab.b);
171    }
172
173    public static ColorXyz convertCieLabToXyz(final double l, final double a, final double b) {
174        double varY = (l + 16) / 116.0;
175        double varX = a / 500 + varY;
176        double varZ = varY - b / 200.0;
177
178        varY = unPivotXyz(varY);
179        varX = unPivotXyz(varX);
180        varZ = unPivotXyz(varZ);
181
182        final double x = REF_X * varX; // REF_X = 95.047 Observer= 2°, Illuminant=
183        // D65
184        final double y = REF_Y * varY; // REF_Y = 100.000
185        final double z = REF_Z * varZ; // REF_Z = 108.883
186
187        return new ColorXyz(x, y, z);
188    }
189
190    public static ColorCieLab convertCieLchToCieLab(final ColorCieLch cielch) {
191        return convertCieLchToCieLab(cielch.l, cielch.c, cielch.h);
192    }
193
194    public static ColorCieLab convertCieLchToCieLab(final double l, final double c, final double h) {
195        // Where CIE-H° = 0 ÷ 360°
196
197        // CIE-L* = CIE-L;
198        final double a = Math.cos(degree2radian(h)) * c;
199        final double b = Math.sin(degree2radian(h)) * c;
200
201        return new ColorCieLab(l, a, b);
202    }
203
204    public static ColorXyz convertCieLuvToXyz(final ColorCieLuv cielch) {
205        return convertCieLuvToXyz(cielch.l, cielch.u, cielch.v);
206    }
207
208    public static ColorXyz convertCieLuvToXyz(final double l, final double u, final double v) {
209        // problems here with div by zero
210
211        final double varY = unPivotXyz((l + 16) / 116.0);
212
213        final double refU = 4 * REF_X / (REF_X + 15 * REF_Y + 3 * REF_Z);
214        final double refV = 9 * REF_Y / (REF_X + 15 * REF_Y + 3 * REF_Z);
215        final double varU = u / (13 * l) + refU;
216        final double varV = v / (13 * l) + refV;
217
218        final double y = varY * 100;
219        final double x = -(9 * y * varU) / ((varU - 4) * varV - varU * varV);
220        final double z = (9 * y - 15 * varV * y - varV * x) / (3 * varV);
221
222        return new ColorXyz(x, y, z);
223    }
224
225    public static ColorCmy convertCmykToCmy(final ColorCmyk cmyk) {
226        return convertCmykToCmy(cmyk.c, cmyk.m, cmyk.y, cmyk.k);
227    }
228
229    public static ColorCmy convertCmykToCmy(double c, double m, double y, final double k) {
230        // Where CMYK and CMY values = 0 ÷ 1
231
232        c = c * (1 - k) + k;
233        m = m * (1 - k) + k;
234        y = y * (1 - k) + k;
235
236        return new ColorCmy(c, m, y);
237    }
238
239    public static int convertCmykToRgb(final int c, final int m, final int y, final int k) {
240        final double C = c / 255.0;
241        final double M = m / 255.0;
242        final double Y = y / 255.0;
243        final double K = k / 255.0;
244
245        return convertCmyToRgb(convertCmykToCmy(C, M, Y, K));
246    }
247
248    public static int convertCmykToRgbAdobe(final int sc, final int sm, final int sy, final int sk) {
249        final int red = 255 - (sc + sk);
250        final int green = 255 - (sm + sk);
251        final int blue = 255 - (sy + sk);
252
253        return convertRgbToRgb(red, green, blue);
254    }
255
256    public static ColorCmyk convertCmyToCmyk(final ColorCmy cmy) {
257        // Where CMYK and CMY values = 0 ÷ 1
258
259        double c = cmy.c;
260        double m = cmy.m;
261        double y = cmy.y;
262
263        double varK = 1.0;
264
265        if (c < varK) {
266            varK = c;
267        }
268        if (m < varK) {
269            varK = m;
270        }
271        if (y < varK) {
272            varK = y;
273        }
274        if (varK == 1) { // Black
275            c = 0;
276            m = 0;
277            y = 0;
278        } else {
279            c = (c - varK) / (1 - varK);
280            m = (m - varK) / (1 - varK);
281            y = (y - varK) / (1 - varK);
282        }
283        return new ColorCmyk(c, m, y, varK);
284    }
285
286    public static int convertCmyToRgb(final ColorCmy cmy) {
287        // From Ghostscript's gdevcdj.c:
288        // * Ghostscript: R = (1.0 - C) * (1.0 - K)
289        // * Adobe: R = 1.0 - min(1.0, C + K)
290        // and similarly for G and B.
291        // This is Ghostscript's formula with K = 0.
292
293        // CMY values = 0 ÷ 1
294        // RGB values = 0 ÷ 255
295
296        final double r = (1 - cmy.c) * 255.0;
297        final double g = (1 - cmy.m) * 255.0;
298        final double b = (1 - cmy.y) * 255.0;
299
300        return convertRgbToRgb(r, g, b);
301    }
302
303    public static ColorCieLab convertDin99bLabToCieLab(final ColorDin99Lab dinb) {
304        return convertDin99bLabToCieLab(dinb.l99, dinb.a99, dinb.b99);
305    }
306
307    public static ColorCieLab convertDin99bLabToCieLab(final double L99b, final double a99b, final double b99b) {
308        final double kE = 1.0; // brightness factor, 1.0 for CIE reference conditions
309        final double kCH = 1.0; // chroma and hue factor, 1.0 for CIE reference conditions
310        final double fac1 = 100.0 / Math.log(129.0 / 50.0); // L99 scaling factor = 105.50867113783109
311        final double ang = Math.toRadians(16.0);
312
313        final double hef = Math.atan2(b99b, a99b);
314        final double c = Math.sqrt(a99b * a99b + b99b * b99b);
315        final double g = (Math.exp(0.045 * c * kCH * kE) - 1.0) / 0.045;
316        final double e = g * Math.cos(hef);
317        final double f = g * Math.sin(hef) / 0.7;
318
319        final double l = (Math.exp(L99b * kE / fac1) - 1.) / 0.0158;
320        final double a = e * Math.cos(ang) - f * Math.sin(ang);
321        final double b = e * Math.sin(ang) + f * Math.cos(ang);
322        return new ColorCieLab(l, a, b);
323    }
324
325    /**
326     * DIN99o.
327     *
328     * @param dino color in the DIN99 color space.
329     * @return DIN99o colors converted to CIELab color space.
330     * @see <a href=
331     *      "https://de.wikipedia.org/w/index.php?title=Diskussion:DIN99-Farbraum">https://de.wikipedia.org/w/index.php?title=Diskussion:DIN99-Farbraum</a>
332     */
333    public static ColorCieLab convertDin99oLabToCieLab(final ColorDin99Lab dino) {
334        return convertDin99oLabToCieLab(dino.l99, dino.a99, dino.b99);
335    }
336
337    /**
338     * DIN99o.
339     *
340     * @param l99o lightness of color.
341     * @param a99o position between red and green.
342     * @param b99o position between yellow and blue.
343     * @return DIN99o colors converted to CIELab color space.
344     * @see <a href=
345     *      "https://de.wikipedia.org/w/index.php?title=Diskussion:DIN99-Farbraum">https://de.wikipedia.org/w/index.php?title=Diskussion:DIN99-Farbraum</a>
346     */
347    public static ColorCieLab convertDin99oLabToCieLab(final double l99o, final double a99o, final double b99o) {
348        final double kE = 1.0; // brightness factor, 1.0 for CIE reference conditions
349        final double kCH = 1.0; // chroma and hue factor, 1.0 for CIE reference conditions
350        final double fac1 = 100.0 / Math.log(139.0 / 100.0); // L99 scaling factor = 303.67100547050995
351        final double ang = Math.toRadians(26.0);
352
353        final double l = (Math.exp(l99o * kE / fac1) - 1.0) / 0.0039;
354
355        final double h99ef = Math.atan2(b99o, a99o); // arctan in four quadrants
356
357        final double heofo = h99ef - ang; // backwards hue rotation
358
359        final double c99 = Math.sqrt(a99o * a99o + b99o * b99o); // DIN99 chroma
360        final double g = (Math.exp(0.0435 * kE * kCH * c99) - 1.0) / 0.075; // factor for chroma decompression and viewing conditions
361        final double e = g * Math.cos(heofo);
362        final double f = g * Math.sin(heofo);
363
364        final double a = e * Math.cos(ang) - f / 0.83 * Math.sin(ang); // rotation by 26 degrees
365        final double b = e * Math.sin(ang) + f / 0.83 * Math.cos(ang); // rotation by 26 degrees
366
367        return new ColorCieLab(l, a, b);
368    }
369
370    public static int convertHslToRgb(final ColorHsl hsl) {
371        return convertHslToRgb(hsl.h, hsl.s, hsl.l);
372    }
373
374    public static int convertHslToRgb(final double h, final double s, final double l) {
375        final double r;
376        final double g;
377        final double b;
378        if (s == 0) {
379            // HSL values = 0 ÷ 1
380            r = l * 255; // RGB results = 0 ÷ 255
381            g = l * 255;
382            b = l * 255;
383        } else {
384            final double var2;
385
386            if (l < 0.5) {
387                var2 = l * (1 + s);
388            } else {
389                var2 = l + s - s * l;
390            }
391
392            final double var1 = 2 * l - var2;
393
394            r = 255 * convertHueToRgb(var1, var2, h + 1 / 3.0);
395            g = 255 * convertHueToRgb(var1, var2, h);
396            b = 255 * convertHueToRgb(var1, var2, h - 1 / 3.0);
397        }
398
399        return convertRgbToRgb(r, g, b);
400    }
401
402    public static int convertHsvToRgb(final ColorHsv HSV) {
403        return convertHsvToRgb(HSV.h, HSV.s, HSV.v);
404    }
405
406    public static int convertHsvToRgb(final double h, final double s, final double v) {
407        final double r;
408        final double g;
409        final double b;
410        if (s == 0) {
411            // HSV values = 0 ÷ 1
412            r = v * 255;
413            g = v * 255;
414            b = v * 255;
415        } else {
416            double varH = h * 6;
417            if (varH == 6) {
418                varH = 0; // H must be < 1
419            }
420            final double varI = Math.floor(varH); // Or ... varI = floor( varH )
421            final double var1 = v * (1 - s);
422            final double var2 = v * (1 - s * (varH - varI));
423            final double var3 = v * (1 - s * (1 - (varH - varI)));
424
425            final double varR;
426            final double varG;
427            final double varB;
428
429            if (varI == 0) {
430                varR = v;
431                varG = var3;
432                varB = var1;
433            } else if (varI == 1) {
434                varR = var2;
435                varG = v;
436                varB = var1;
437            } else if (varI == 2) {
438                varR = var1;
439                varG = v;
440                varB = var3;
441            } else if (varI == 3) {
442                varR = var1;
443                varG = var2;
444                varB = v;
445            } else if (varI == 4) {
446                varR = var3;
447                varG = var1;
448                varB = v;
449            } else {
450                varR = v;
451                varG = var1;
452                varB = var2;
453            }
454
455            r = varR * 255; // RGB results = 0 ÷ 255
456            g = varG * 255;
457            b = varB * 255;
458        }
459
460        return convertRgbToRgb(r, g, b);
461    }
462
463    private static double convertHueToRgb(final double v1, final double v2, double vH) {
464        if (vH < 0) {
465            vH += 1;
466        }
467        if (vH > 1) {
468            vH -= 1;
469        }
470        if (6 * vH < 1) {
471            return v1 + (v2 - v1) * 6 * vH;
472        }
473        if (2 * vH < 1) {
474            return v2;
475        }
476        if (3 * vH < 2) {
477            return v1 + (v2 - v1) * (2 / 3.0 - vH) * 6;
478        }
479        return v1;
480    }
481
482    public static ColorXyz convertHunterLabToXyz(final ColorHunterLab cielab) {
483        return convertHunterLabToXyz(cielab.l, cielab.a, cielab.b);
484    }
485
486    public static ColorXyz convertHunterLabToXyz(final double l, final double a, final double b) {
487        final double varY = l / 10;
488        final double varX = a / 17.5 * l / 10;
489        final double varZ = b / 7 * l / 10;
490
491        final double y = Math.pow(varY, 2);
492        final double x = (varX + y) / 1.02;
493        final double z = -(varZ - y) / 0.847;
494
495        return new ColorXyz(x, y, z);
496    }
497
498    public static ColorCmy convertRgbToCmy(final int rgb) {
499        final int r = 0xff & rgb >> 16;
500        final int g = 0xff & rgb >> 8;
501        final int b = 0xff & rgb >> 0;
502
503        // RGB values = 0 ÷ 255
504        // CMY values = 0 ÷ 1
505
506        final double c = 1 - r / 255.0;
507        final double m = 1 - g / 255.0;
508        final double y = 1 - b / 255.0;
509
510        return new ColorCmy(c, m, y);
511    }
512
513    public static ColorHsl convertRgbToHsl(final int rgb) {
514
515        final int r = 0xff & rgb >> 16;
516        final int g = 0xff & rgb >> 8;
517        final int b = 0xff & rgb >> 0;
518
519        final double varR = r / 255.0; // Where RGB values = 0 ÷ 255
520        final double varG = g / 255.0;
521        final double varB = b / 255.0;
522
523        final double varMin = Math.min(varR, Math.min(varG, varB)); // Min. value
524                                                                    // of RGB
525        final double varMax;
526        boolean maxIsR = false;
527        boolean maxIsG = false;
528        if (varR >= varG && varR >= varB) {
529            varMax = varR;
530            maxIsR = true;
531        } else if (varG > varB) {
532            varMax = varG;
533            maxIsG = true;
534        } else {
535            varMax = varB;
536        }
537        final double delMax = varMax - varMin; // Delta RGB value
538
539        final double l = (varMax + varMin) / 2.0;
540
541        double h;
542        final double s;
543        // Debug.debug("del_Max", del_Max);
544        if (delMax == 0) {
545            // This is a gray, no chroma...
546
547            h = 0; // HSL results = 0 ÷ 1
548            s = 0;
549        } else {
550            // Chromatic data...
551
552            // Debug.debug("L", L);
553
554            if (l < 0.5) {
555                s = delMax / (varMax + varMin);
556            } else {
557                s = delMax / (2 - varMax - varMin);
558            }
559
560            // Debug.debug("S", S);
561
562            final double delR = ((varMax - varR) / 6 + delMax / 2) / delMax;
563            final double delG = ((varMax - varG) / 6 + delMax / 2) / delMax;
564            final double delB = ((varMax - varB) / 6 + delMax / 2) / delMax;
565
566            if (maxIsR) {
567                h = delB - delG;
568            } else if (maxIsG) {
569                h = 1 / 3.0 + delR - delB;
570            } else {
571                h = 2 / 3.0 + delG - delR;
572            }
573
574            // Debug.debug("H1", H);
575
576            if (h < 0) {
577                h += 1;
578            }
579            if (h > 1) {
580                h -= 1;
581            }
582
583            // Debug.debug("H2", H);
584        }
585
586        return new ColorHsl(h, s, l);
587    }
588
589    public static ColorHsv convertRgbToHsv(final int rgb) {
590        final int r = 0xff & rgb >> 16;
591        final int g = 0xff & rgb >> 8;
592        final int b = 0xff & rgb >> 0;
593
594        final double varR = r / 255.0; // RGB values = 0 ÷ 255
595        final double varG = g / 255.0;
596        final double varB = b / 255.0;
597
598        final double varMin = Math.min(varR, Math.min(varG, varB)); // Min. value
599                                                                    // of RGB
600        boolean maxIsR = false;
601        boolean maxIsG = false;
602        final double varMax;
603        if (varR >= varG && varR >= varB) {
604            varMax = varR;
605            maxIsR = true;
606        } else if (varG > varB) {
607            varMax = varG;
608            maxIsG = true;
609        } else {
610            varMax = varB;
611        }
612        final double delMax = varMax - varMin; // Delta RGB value
613
614        final double v = varMax;
615
616        double h;
617        final double s;
618        if (delMax == 0) {
619            // This is a gray, no chroma...
620            h = 0; // HSV results = 0 ÷ 1
621            s = 0;
622        } else {
623            // Chromatic data...
624            s = delMax / varMax;
625
626            final double delR = ((varMax - varR) / 6 + delMax / 2) / delMax;
627            final double delG = ((varMax - varG) / 6 + delMax / 2) / delMax;
628            final double delB = ((varMax - varB) / 6 + delMax / 2) / delMax;
629
630            if (maxIsR) {
631                h = delB - delG;
632            } else if (maxIsG) {
633                h = 1 / 3.0 + delR - delB;
634            } else {
635                h = 2 / 3.0 + delG - delR;
636            }
637
638            if (h < 0) {
639                h += 1;
640            }
641            if (h > 1) {
642                h -= 1;
643            }
644        }
645
646        return new ColorHsv(h, s, v);
647    }
648
649    private static int convertRgbToRgb(final double r, final double g, final double b) {
650        int red = (int) Math.round(r);
651        int green = (int) Math.round(g);
652        int blue = (int) Math.round(b);
653
654        red = Math.min(255, Math.max(0, red));
655        green = Math.min(255, Math.max(0, green));
656        blue = Math.min(255, Math.max(0, blue));
657
658        final int alpha = 0xff;
659
660        return alpha << 24 | red << 16 | green << 8 | blue << 0;
661    }
662
663    private static int convertRgbToRgb(int red, int green, int blue) {
664        red = Math.min(255, Math.max(0, red));
665        green = Math.min(255, Math.max(0, green));
666        blue = Math.min(255, Math.max(0, blue));
667
668        final int alpha = 0xff;
669
670        return alpha << 24 | red << 16 | green << 8 | blue << 0;
671    }
672
673    // See also c# implementation:
674    // https://github.com/muak/ColorMinePortable/blob/master/ColorMinePortable/ColorSpaces/Conversions/XyzConverter.cs
675    public static ColorXyz convertRgbToXyz(final int rgb) {
676        final int r = 0xff & rgb >> 16;
677        final int g = 0xff & rgb >> 8;
678        final int b = 0xff & rgb >> 0;
679
680        double varR = r / 255.0; // Where R = 0 ÷ 255
681        double varG = g / 255.0; // Where G = 0 ÷ 255
682        double varB = b / 255.0; // Where B = 0 ÷ 255
683
684        // Pivot RGB:
685        varR = unPivotRgb(varR);
686        varG = unPivotRgb(varG);
687        varB = unPivotRgb(varB);
688
689        varR *= 100;
690        varG *= 100;
691        varB *= 100;
692
693        // Observer. = 2°, Illuminant = D65
694        // see: https://github.com/StanfordHCI/c3/blob/master/java/src/edu/stanford/vis/color/LAB.java
695        final double X = varR * 0.4124564 + varG * 0.3575761 + varB * 0.1804375;
696        final double Y = varR * 0.2126729 + varG * 0.7151522 + varB * 0.0721750;
697        final double Z = varR * 0.0193339 + varG * 0.1191920 + varB * 0.9503041;
698
699        // Attention: A lot of sources do list these values with less precision. But it makes a visual difference:
700        // final double X = var_R * 0.4124 + var_G * 0.3576 + var_B * 0.1805;
701        // final double Y = var_R * 0.2126 + var_G * 0.7152 + var_B * 0.0722;
702        // final double Z = var_R * 0.0193 + var_G * 0.1192 + var_B * 0.9505;
703
704        return new ColorXyz(X, Y, Z);
705    }
706
707    public static ColorCieLuv convertXuzToCieLuv(final double x, final double y, final double z) {
708        // problems here with div by zero
709
710        final double varU = 4 * x / (x + 15 * y + 3 * z);
711        final double varV = 9 * y / (x + 15 * y + 3 * z);
712
713        // Debug.debug("var_U", var_U);
714        // Debug.debug("var_V", var_V);
715
716        double varY = y / 100.0;
717        // Debug.debug("var_Y", var_Y);
718
719        varY = pivotXyz(varY);
720
721        // Debug.debug("var_Y", var_Y);
722
723        final double refU = 4 * REF_X / (REF_X + 15 * REF_Y + 3 * REF_Z);
724        final double refV = 9 * REF_Y / (REF_X + 15 * REF_Y + 3 * REF_Z);
725
726        // Debug.debug("ref_U", ref_U);
727        // Debug.debug("ref_V", ref_V);
728
729        final double l = 116 * varY - 16;
730        final double u = 13 * l * (varU - refU);
731        final double v = 13 * l * (varV - refV);
732
733        return new ColorCieLuv(l, u, v);
734    }
735
736    public static ColorCieLab convertXyzToCieLab(final ColorXyz xyz) {
737        return convertXyzToCieLab(xyz.x, xyz.y, xyz.z);
738    }
739
740    public static ColorCieLab convertXyzToCieLab(final double x, final double y, final double z) {
741
742        double varX = x / REF_X; // REF_X = 95.047 Observer= 2°, Illuminant= D65
743        double varY = y / REF_Y; // REF_Y = 100.000
744        double varZ = z / REF_Z; // REF_Z = 108.883
745
746        // Pivot XÝZ:
747        varX = pivotXyz(varX);
748        varY = pivotXyz(varY);
749        varZ = pivotXyz(varZ);
750
751        // Math.max added from https://github.com/muak/ColorMinePortable/blob/master/ColorMinePortable/ColorSpaces/Conversions/LabConverter.cs
752        final double l = Math.max(0, 116 * varY - 16);
753        final double a = 500 * (varX - varY);
754        final double b = 200 * (varY - varZ);
755        return new ColorCieLab(l, a, b);
756    }
757
758    public static ColorCieLuv convertXyzToCieLuv(final ColorXyz xyz) {
759        return convertXuzToCieLuv(xyz.x, xyz.y, xyz.z);
760    }
761
762    public static ColorHunterLab convertXyzToHunterLab(final ColorXyz xyz) {
763        return convertXyzToHunterLab(xyz.x, xyz.y, xyz.z);
764    }
765
766    public static ColorHunterLab convertXyzToHunterLab(final double x, final double y, final double z) {
767        final double l = 10 * Math.sqrt(y);
768        final double a = y == 0.0 ? 0.0 : 17.5 * ((1.02 * x - y) / Math.sqrt(y));
769        final double b = y == 0.0 ? 0.0 : 7 * ((y - 0.847 * z) / Math.sqrt(y));
770
771        return new ColorHunterLab(l, a, b);
772    }
773
774    public static int convertXyzToRgb(final ColorXyz xyz) {
775        return convertXyzToRgb(xyz.x, xyz.y, xyz.z);
776    }
777
778    public static int convertXyzToRgb(final double x, final double y, final double z) {
779        // Observer = 2°, Illuminant = D65
780        final double varX = x / 100.0; // Where X = 0 ÷ 95.047
781        final double varY = y / 100.0; // Where Y = 0 ÷ 100.000
782        final double varZ = z / 100.0; // Where Z = 0 ÷ 108.883
783
784        // see: https://github.com/StanfordHCI/c3/blob/master/java/src/edu/stanford/vis/color/LAB.java
785        double varR = varX * 3.2404542 + varY * -1.5371385 + varZ * -0.4985314;
786        double varG = varX * -0.9692660 + varY * 1.8760108 + varZ * 0.0415560;
787        double varB = varX * 0.0556434 + varY * -0.2040259 + varZ * 1.0572252;
788
789        // Attention: A lot of sources do list these values with less precision. But it makes a visual difference:
790        // double var_R = var_X * 3.2406 + var_Y * -1.5372 + var_Z * -0.4986;
791        // double var_G = var_X * -0.9689 + var_Y * 1.8758 + var_Z * 0.0415;
792        // double var_B = var_X * 0.0557 + var_Y * -0.2040 + var_Z * 1.0570;
793
794        varR = pivotRgb(varR);
795        varG = pivotRgb(varG);
796        varB = pivotRgb(varB);
797
798        final double r = varR * 255;
799        final double g = varG * 255;
800        final double b = varB * 255;
801        return convertRgbToRgb(r, g, b);
802    }
803
804    public static double degree2radian(final double degree) {
805        return degree * Math.PI / 180.0;
806    }
807
808    private static double pivotRgb(double n) {
809        if (n > 0.0031308) {
810            n = 1.055 * Math.pow(n, 1 / 2.4) - 0.055;
811        } else {
812            n = 12.92 * n;
813        }
814        return n;
815    }
816
817    private static double pivotXyz(double n) {
818        if (n > XYZ_t0) {
819            n = Math.pow(n, 1 / 3.0);
820        } else {
821            n = XYZ_m * n + 16 / 116.0;
822        }
823        return n;
824    }
825
826    public static double radian2degree(final double radian) {
827        return radian * 180.0 / Math.PI;
828    }
829
830    private static double square(final double f) {
831        return f * f;
832    }
833
834    private static double unPivotRgb(double n) {
835        if (n > 0.04045) {
836            n = Math.pow((n + 0.055) / 1.055, 2.4);
837        } else {
838            n /= 12.92;
839        }
840        return n;
841    }
842
843    private static double unPivotXyz(double n) {
844        final double nCube = Math.pow(n, 3);
845        if (nCube > XYZ_t0) {
846            n = nCube;
847        } else {
848            n = (n - 16 / 116.0) / XYZ_m;
849        }
850        return n;
851    }
852
853    private ColorConversions() {
854    }
855
856}