[GitHub] [commons-imaging] Brixomatic commented on a change in pull request #114: imaging.color extension. More precision and DIN99b + DIN99o added to ColorConversion.

[GitBox <gi...@apache.org>]

Brixomatic commented on a change in pull request #114:
URL: https://github.com/apache/commons-imaging/pull/114#discussion_r548983060



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File path: src/main/java/org/apache/commons/imaging/color/ColorConversions.java
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@@ -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:
       If Y == 0.0 (as with black color) "a" and "b" would become "NaN", this the same fix that colormine uses (see [HunterLabConverter.cs](https://github.com/muak/ColorMine/blob/master/ColorMine/ColorSpaces/Conversions/HunterLabConverter.cs) )




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