kinow commented on a change in pull request #114:
URL: https://github.com/apache/commons-imaging/pull/114#discussion_r588951722
##########
File path: src/main/java/org/apache/commons/imaging/color/ColorConversions.java
##########
@@ -747,4 +679,147 @@ public static ColorXyz convertCIELuvtoXYZ(final double L,
final double u, final
return new ColorXyz(X, Y, Z);
}
+
+ public static ColorDIN99Lab convertCIELabToDIN99bLab(final ColorCieLab
cie) {
+ return convertCIELabToDIN99bLab(cie.L, cie.a, cie.b);
+ }
+
+ public static ColorDIN99Lab convertCIELabToDIN99bLab(final double L, final
double a, final double b) {
+ final double FAC_1 = 100.0 / Math.log(129.0 / 50.0); // = 105.51
+ final double kE = 1.0; // brightness factor, 1.0 for CIE reference
conditions
+ final double kCH = 1.0; // chroma and hue factor, 1.0 for CIE
reference conditions
+ final double ang = Math.toRadians(16.0);
+
+ final double L99 = kE * FAC_1 * Math.log(1. + 0.0158 * L);
+ double a99 = 0.0;
+ double b99 = 0.0;
+ if (a != 0.0 || b != 0.0) {
+ final double e = a * Math.cos(ang) + b * Math.sin(ang);
+ final double f = 0.7 * (b * Math.cos(ang) - a * Math.sin(ang));
+ final double G = Math.sqrt(e * e + f * f);
+ if (G != 0.) {
+ final double k = Math.log(1. + 0.045 * G) / (0.045 * kCH * kE
* G);
+ a99 = k * e;
+ b99 = k * f;
+ }
+ }
+ return new ColorDIN99Lab(L99, a99, b99);
+ }
+
+ public static ColorCieLab convertDIN99bLabToCIELab(final ColorDIN99Lab
dinb) {
+ return convertDIN99bLabToCIELab(dinb.L99, dinb.a99, dinb.b99);
+ }
+
+ public static ColorCieLab convertDIN99bLabToCIELab(final double L99b,
final double a99b, final double b99b) {
+ final double kE = 1.0; // brightness factor, 1.0 for CIE reference
conditions
+ final double kCH = 1.0; // chroma and hue factor, 1.0 for CIE
reference conditions
+ final double FAC_1 = 100.0 / Math.log(129.0 / 50.0); // L99 scaling
factor = 105.50867113783109
+ final double ang = Math.toRadians(16.0);
+
+ final double hef = Math.atan2(b99b, a99b);
+ final double C = Math.sqrt(a99b * a99b + b99b * b99b);
+ final double G = (Math.exp(0.045 * C * kCH * kE) - 1.0) / 0.045;
+ final double e = G * Math.cos(hef);
+ final double f = G * Math.sin(hef) / 0.7;
+
+ final double L = (Math.exp(L99b * kE / FAC_1) - 1.) / 0.0158;
+ final double a = e * Math.cos(ang) - f * Math.sin(ang);
+ final double b = e * Math.sin(ang) + f * Math.cos(ang);
+ return new ColorCieLab(L, a, b);
+ }
+
+ /** DIN99o, see:
https://de.wikipedia.org/w/index.php?title=Diskussion:DIN99-Farbraum */
+ public static ColorDIN99Lab convertCIELabToDIN99oLab(final ColorCieLab
cie) {
+ return convertCIELabToDIN99oLab(cie.L, cie.a, cie.b);
+ }
+
+ /** DIN99o, see:
https://de.wikipedia.org/w/index.php?title=Diskussion:DIN99-Farbraum */
+ public static ColorDIN99Lab convertCIELabToDIN99oLab(final double L, final
double a, final double b) {
+ final double kE = 1.0; // brightness factor, 1.0 for CIE reference
conditions
+ final double kCH = 1.0; // chroma and hue factor, 1.0 for CIE
reference conditions
+ final double FAC_1 = 100.0 / Math.log(139.0 / 100.0); // L99 scaling
factor = 303.67100547050995
+ final double ang = Math.toRadians(26.0);
+
+ final double L99o = FAC_1 / kE * Math.log(1 + 0.0039 * L); //
Lightness correction kE
+ double a99o = 0.0;
+ double b99o = 0.0;
+ if (a != 0.0 || b != 0.0) {
+ final double eo = a * Math.cos(ang) + b * Math.sin(ang); // a
stretching
+ final double fo = 0.83 * (b * Math.cos(ang) - a * Math.sin(ang));
// b rotation/stretching
+ final double Go = Math.sqrt(eo * eo + fo * fo); // chroma
+ final double C99o = Math.log(1.0 + 0.075 * Go) / (0.0435 * kCH *
kE); // factor for chroma compression and viewing conditions
+ final double heofo = Math.atan2(fo, eo); // arctan in four
quadrants
+ final double h99o = heofo + ang; // hue rotation
+ a99o = C99o * Math.cos(h99o);
+ b99o = C99o * Math.sin(h99o);
+ }
+ return new ColorDIN99Lab(L99o, a99o, b99o);
+ }
+
+ /** DIN99o, see:
https://de.wikipedia.org/w/index.php?title=Diskussion:DIN99-Farbraum */
+ public static ColorCieLab convertDIN99oLabToCIELab(final ColorDIN99Lab
dino) {
+ return convertDIN99oLabToCIELab(dino.L99, dino.a99, dino.b99);
+ }
+
+ /** DIN99o, see:
https://de.wikipedia.org/w/index.php?title=Diskussion:DIN99-Farbraum */
+ public static ColorCieLab convertDIN99oLabToCIELab(final double L99o,
final double a99o, final double b99o) {
+ final double kE = 1.0; // brightness factor, 1.0 for CIE reference
conditions
+ final double kCH = 1.0; // chroma and hue factor, 1.0 for CIE
reference conditions
+ final double FAC_1 = 100.0 / Math.log(139.0 / 100.0); // L99 scaling
factor = 303.67100547050995
+ final double ang = Math.toRadians(26.0);
+
+ final double L = (Math.exp(L99o * kE / FAC_1) - 1.0) / 0.0039;
+
+ final double h99ef = Math.atan2(b99o, a99o); // arctan in four
quadrants
+
+ final double heofo = h99ef - ang; // backwards hue rotation
+
+ final double C99 = Math.sqrt(a99o * a99o + b99o * b99o); // DIN99
chroma
+ final double G = (Math.exp(0.0435 * kE * kCH * C99) - 1.0) / 0.075; //
factor for chroma decompression and viewing conditions
+ final double e = G * Math.cos(heofo);
+ final double f = G * Math.sin(heofo);
+
+ final double a = e * Math.cos(ang) - f / 0.83 * Math.sin(ang); //
rotation by 26 degrees
+ final double b = e * Math.sin(ang) + f / 0.83 * Math.cos(ang); //
rotation by 26 degrees
+
+ return new ColorCieLab(L, a, b);
+ }
+
+ private static double pivotRGB(double n) {
+ if (n > 0.0031308) {
+ n = 1.055 * Math.pow(n, 1 / 2.4) - 0.055;
+ } else {
+ n = 12.92 * n;
+ }
+ return n;
+ }
+
+ private static double unPivotRGB(double n) {
+ if (n > 0.04045) {
+ n = Math.pow((n + 0.055) / 1.055, 2.4);
+ } else {
+ n = n / 12.92;
+ }
+ return n;
+ }
+
+ private static double pivotXYZ(double n) {
+ if (n > XYZ_t0) {
+ n = Math.pow(n, 1 / 3.0);
+ } else {
+ n = XYZ_m * n + 16 / 116.0;
+ }
+ return n;
+ }
+
+ private static double unPivotXYZ(double n) {
+ final double nCube = Math.pow(n, 3);
+ if (nCube > XYZ_t0) {
+ n = nCube;
+ } else {
+ n = (n - 16 / 116.0) / XYZ_m;
+ }
+ return n;
Review comment:
These functions here are removing **a lot** of duplicate code. Thanks
for tidying it up.
##########
File path: src/main/java/org/apache/commons/imaging/color/ColorConversions.java
##########
@@ -99,8 +89,8 @@ public static ColorHunterLab convertXYZtoHunterLab(final
ColorXyz xyz) {
public static ColorHunterLab convertXYZtoHunterLab(final double X,
final double Y, final double Z) {
final double L = 10 * Math.sqrt(Y);
- final double a = 17.5 * (((1.02 * X) - Y) / Math.sqrt(Y));
- final double b = 7 * ((Y - (0.847 * Z)) / Math.sqrt(Y));
+ final double a = Y == 0.0 ? 0.0 : 17.5 * (((1.02 * X) - Y) /
Math.sqrt(Y));
+ final double b = Y == 0.0 ? 0.0 : 7 * ((Y - (0.847 * Z)) /
Math.sqrt(Y));
Review comment:
Oh, good catch! :clap:
##########
File path: src/main/java/org/apache/commons/imaging/color/ColorConversions.java
##########
@@ -747,4 +679,147 @@ public static ColorXyz convertCIELuvtoXYZ(final double L,
final double u, final
return new ColorXyz(X, Y, Z);
}
+
+ public static ColorDIN99Lab convertCIELabToDIN99bLab(final ColorCieLab
cie) {
+ return convertCIELabToDIN99bLab(cie.L, cie.a, cie.b);
+ }
+
+ public static ColorDIN99Lab convertCIELabToDIN99bLab(final double L, final
double a, final double b) {
+ final double FAC_1 = 100.0 / Math.log(129.0 / 50.0); // = 105.51
+ final double kE = 1.0; // brightness factor, 1.0 for CIE reference
conditions
+ final double kCH = 1.0; // chroma and hue factor, 1.0 for CIE
reference conditions
+ final double ang = Math.toRadians(16.0);
+
+ final double L99 = kE * FAC_1 * Math.log(1. + 0.0158 * L);
+ double a99 = 0.0;
+ double b99 = 0.0;
+ if (a != 0.0 || b != 0.0) {
+ final double e = a * Math.cos(ang) + b * Math.sin(ang);
+ final double f = 0.7 * (b * Math.cos(ang) - a * Math.sin(ang));
+ final double G = Math.sqrt(e * e + f * f);
+ if (G != 0.) {
+ final double k = Math.log(1. + 0.045 * G) / (0.045 * kCH * kE
* G);
+ a99 = k * e;
+ b99 = k * f;
+ }
+ }
+ return new ColorDIN99Lab(L99, a99, b99);
+ }
+
+ public static ColorCieLab convertDIN99bLabToCIELab(final ColorDIN99Lab
dinb) {
+ return convertDIN99bLabToCIELab(dinb.L99, dinb.a99, dinb.b99);
+ }
+
+ public static ColorCieLab convertDIN99bLabToCIELab(final double L99b,
final double a99b, final double b99b) {
+ final double kE = 1.0; // brightness factor, 1.0 for CIE reference
conditions
+ final double kCH = 1.0; // chroma and hue factor, 1.0 for CIE
reference conditions
+ final double FAC_1 = 100.0 / Math.log(129.0 / 50.0); // L99 scaling
factor = 105.50867113783109
+ final double ang = Math.toRadians(16.0);
+
+ final double hef = Math.atan2(b99b, a99b);
+ final double C = Math.sqrt(a99b * a99b + b99b * b99b);
+ final double G = (Math.exp(0.045 * C * kCH * kE) - 1.0) / 0.045;
+ final double e = G * Math.cos(hef);
+ final double f = G * Math.sin(hef) / 0.7;
+
+ final double L = (Math.exp(L99b * kE / FAC_1) - 1.) / 0.0158;
+ final double a = e * Math.cos(ang) - f * Math.sin(ang);
+ final double b = e * Math.sin(ang) + f * Math.cos(ang);
+ return new ColorCieLab(L, a, b);
+ }
+
+ /** DIN99o, see:
https://de.wikipedia.org/w/index.php?title=Diskussion:DIN99-Farbraum */
Review comment:
:+1:
Thanks for keeping variables similar to the original text. With some machine
translation from German to English, and following your code, I think I've
managed to review these functions :-)
##########
File path: src/main/java/org/apache/commons/imaging/color/ColorConversions.java
##########
@@ -168,30 +152,24 @@ public static ColorXyz convertRGBtoXYZ(final int rgb) {
double var_G = g / 255.0; // Where G = 0 ÷ 255
double var_B = b / 255.0; // Where B = 0 ÷ 255
- if (var_R > 0.04045) {
- var_R = Math.pow((var_R + 0.055) / 1.055, 2.4);
- } else {
- var_R = var_R / 12.92;
- }
- if (var_G > 0.04045) {
- var_G = Math.pow((var_G + 0.055) / 1.055, 2.4);
- } else {
- var_G = var_G / 12.92;
- }
- if (var_B > 0.04045) {
- var_B = Math.pow((var_B + 0.055) / 1.055, 2.4);
- } else {
- var_B = var_B / 12.92;
- }
+ // Pivot RGB:
+ var_R = unPivotRGB(var_R);
+ var_G = unPivotRGB(var_G);
+ var_B = unPivotRGB(var_B);
- var_R = var_R * 100;
- var_G = var_G * 100;
- var_B = var_B * 100;
+ var_R *= 100;
+ var_G *= 100;
+ var_B *= 100;
// Observer. = 2°, Illuminant = D65
- final double X = var_R * 0.4124 + var_G * 0.3576 + var_B * 0.1805;
- final double Y = var_R * 0.2126 + var_G * 0.7152 + var_B * 0.0722;
- final double Z = var_R * 0.0193 + var_G * 0.1192 + var_B * 0.9505;
+ // see:
https://github.com/StanfordHCI/c3/blob/master/java/src/edu/stanford/vis/color/LAB.java
+ final double X = var_R * 0.4124564 + var_G * 0.3575761 + var_B *
0.1804375;
+ final double Y = var_R * 0.2126729 + var_G * 0.7151522 + var_B *
0.0721750;
+ final double Z = var_R * 0.0193339 + var_G * 0.1191920 + var_B *
0.9503041;
+
+ // final double X = var_R * 0.4124 + var_G * 0.3576 + var_B * 0.1805;
+ // final double Y = var_R * 0.2126 + var_G * 0.7152 + var_B * 0.0722;
+ // final double Z = var_R * 0.0193 + var_G * 0.1192 + var_B * 0.9505;
Review comment:
Was it intentionally commented, or left-overs from the
development/testing?
##########
File path: src/main/java/org/apache/commons/imaging/color/ColorConversions.java
##########
@@ -747,4 +700,147 @@ public static ColorXyz convertCIELuvtoXYZ(final double L,
final double u, final
return new ColorXyz(X, Y, Z);
}
+
+ public static ColorDIN99Lab convertCIELabToDIN99bLab(final ColorCieLab
cie) {
+ return convertCIELabToDIN99bLab(cie.L, cie.a, cie.b);
+ }
+
+ public static ColorDIN99Lab convertCIELabToDIN99bLab(final double L, final
double a, final double b) {
+ final double FAC_1 = 100.0 / Math.log(129.0 / 50.0); // = 105.51
+ final double kE = 1.0; // brightness factor, 1.0 for CIE reference
conditions
+ final double kCH = 1.0; // chroma and hue factor, 1.0 for CIE
reference conditions
+ final double ang = Math.toRadians(16.0);
+
+ final double L99 = kE * FAC_1 * Math.log(1. + 0.0158 * L);
+ double a99 = 0.0;
+ double b99 = 0.0;
+ if (a != 0.0 || b != 0.0) {
+ final double e = a * Math.cos(ang) + b * Math.sin(ang);
+ final double f = 0.7 * (b * Math.cos(ang) - a * Math.sin(ang));
+ final double G = Math.sqrt(e * e + f * f);
+ if (G != 0.) {
+ final double k = Math.log(1. + 0.045 * G) / (0.045 * kCH * kE
* G);
+ a99 = k * e;
+ b99 = k * f;
+ }
+ }
+ return new ColorDIN99Lab(L99, a99, b99);
+ }
+
+ public static ColorCieLab convertDIN99bLabToCIELab(final ColorDIN99Lab
dinb) {
+ return convertDIN99bLabToCIELab(dinb.L99, dinb.a99, dinb.b99);
+ }
+
+ public static ColorCieLab convertDIN99bLabToCIELab(final double L99b,
final double a99b, final double b99b) {
+ final double kE = 1.0; // brightness factor, 1.0 for CIE reference
conditions
+ final double kCH = 1.0; // chroma and hue factor, 1.0 for CIE
reference conditions
+ final double FAC_1 = 100.0 / Math.log(129.0 / 50.0); // L99 scaling
factor = 105.50867113783109
+ final double ang = Math.toRadians(16.0);
+
+ final double hef = Math.atan2(b99b, a99b);
+ final double C = Math.sqrt(a99b * a99b + b99b * b99b);
+ final double G = (Math.exp(0.045 * C * kCH * kE) - 1.0) / 0.045;
+ final double e = G * Math.cos(hef);
+ final double f = G * Math.sin(hef) / 0.7;
+
+ final double L = (Math.exp(L99b * kE / FAC_1) - 1.) / 0.0158;
+ final double a = e * Math.cos(ang) - f * Math.sin(ang);
+ final double b = e * Math.sin(ang) + f * Math.cos(ang);
+ return new ColorCieLab(L, a, b);
+ }
+
+ /** DIN99o, see:
https://de.wikipedia.org/w/index.php?title=Diskussion:DIN99-Farbraum */
+ public static ColorDIN99Lab convertCIELabToDIN99oLab(final ColorCieLab
cie) {
+ return convertCIELabToDIN99oLab(cie.L, cie.a, cie.b);
+ }
+
+ /** DIN99o, see:
https://de.wikipedia.org/w/index.php?title=Diskussion:DIN99-Farbraum */
+ public static ColorDIN99Lab convertCIELabToDIN99oLab(final double L, final
double a, final double b) {
+ final double kE = 1.0; // brightness factor, 1.0 for CIE reference
conditions
+ final double kCH = 1.0; // chroma and hue factor, 1.0 for CIE
reference conditions
+ final double FAC_1 = 100.0 / Math.log(139.0 / 100.0); // L99 scaling
factor = 303.67100547050995
+ final double ang = Math.toRadians(26.0);
+
+ final double L99o = FAC_1 / kE * Math.log(1 + 0.0039 * L); //
Lightness correction kE
+ double a99o = 0.0;
+ double b99o = 0.0;
+ if (a != 0.0 || b != 0.0) {
+ final double eo = a * Math.cos(ang) + b * Math.sin(ang); // a
stretching
+ final double fo = 0.83 * (b * Math.cos(ang) - a * Math.sin(ang));
// b rotation/stretching
+ final double Go = Math.sqrt(eo * eo + fo * fo); // chroma
+ final double C99o = Math.log(1.0 + 0.075 * Go) / (0.0435 * kCH *
kE); // factor for chroma compression and viewing conditions
+ final double heofo = Math.atan2(fo, eo); // arctan in four
quadrants
+ final double h99o = heofo + ang; // hue rotation
+ a99o = C99o * Math.cos(h99o);
+ b99o = C99o * Math.sin(h99o);
+ }
+ return new ColorDIN99Lab(L99o, a99o, b99o);
+ }
+
+ /** DIN99o, see:
https://de.wikipedia.org/w/index.php?title=Diskussion:DIN99-Farbraum */
+ public static ColorCieLab convertDIN99oLabToCIELab(final ColorDIN99Lab
dino) {
+ return convertDIN99oLabToCIELab(dino.L99, dino.a99, dino.b99);
+ }
+
+ /** DIN99o, see:
https://de.wikipedia.org/w/index.php?title=Diskussion:DIN99-Farbraum */
+ public static ColorCieLab convertDIN99oLabToCIELab(final double L99o,
final double a99o, final double b99o) {
+ final double kE = 1.0; // brightness factor, 1.0 for CIE reference
conditions
+ final double kCH = 1.0; // chroma and hue factor, 1.0 for CIE
reference conditions
+ final double FAC_1 = 100.0 / Math.log(139.0 / 100.0); // L99 scaling
factor = 303.67100547050995
+ final double ang = Math.toRadians(26.0);
+
+ final double L = (Math.exp(L99o * kE / FAC_1) - 1.0) / 0.0039;
+
+ final double h99ef = Math.atan2(b99o, a99o); // arctan in four
quadrants
+
+ final double heofo = h99ef - ang; // backwards hue rotation
+
+ final double C99 = Math.sqrt(a99o * a99o + b99o * b99o); // DIN99
chroma
+ final double G = (Math.exp(0.0435 * kE * kCH * C99) - 1.0) / 0.075; //
factor for chroma decompression and viewing conditions
+ final double e = G * Math.cos(heofo);
+ final double f = G * Math.sin(heofo);
+
+ final double a = e * Math.cos(ang) - f / 0.83 * Math.sin(ang); //
rotation by 26 degrees
+ final double b = e * Math.sin(ang) + f / 0.83 * Math.cos(ang); //
rotation by 26 degrees
+
+ return new ColorCieLab(L, a, b);
+ }
Review comment:
Even though the sources are in German, you've done an excellent job
maintaining this new code as similar as possible to the Wikipedia text, and
also added some comments :+1: Looks good to me.
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