Brixomatic commented on a change in pull request #114:
URL: https://github.com/apache/commons-imaging/pull/114#discussion_r588994104
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File path: src/main/java/org/apache/commons/imaging/color/ColorConversions.java
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@@ -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:
I left them over to make the change more apparent, since most sources
just list the shorter value. If you like I will remove them. For the time
being, I'll add a line of explanation.
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