saturation increase makes pixelated colours

[quapurna]

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xnviewmp: XnView MP Linux, Ver. 0.93.1 64bits (Mar 7 2019)
gimp: 2.8.22
OS: Ubuntu Mate, 18.04.2 (KL 4.15.0-48-generic x86_64)
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If I use xnviewmp to increase the saturation of an image, it is very frequent that some pixelated colours appear.
However, it never happens if I use gimp. The colours spread smoothly.

Please, see the (jpg) images below.

Is there any setting in xnviewmp I should change ?

Thank you.



image 1: original image

duck1-original.jpg

image 2: xnviewmp, saturation increased to 50

duck2-xnviewmp-sat50.jpg

image 3: xnviewmp, saturation increased to 100

duck3-xnviewmp-sat100.jpg

image 4: gimp, saturation increased to 50

duck4-gimp-sat50.jpg

image 5: gimp, saturation increased to 100

duck5-gimp-sat100.jpg

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[xnview]

Thanks to your detailed description I can reproduce

[quapurna]

While waiting for the fix, is there any work-around a user can do to avoid this problem so that I dont have to use another application?

[quapurna]

I am very sorry Pierre, may I know the status of this issue?
Thank you.

[xnview]

currently not fixed