0.96: Resizing images w/ "Use gamma correction" reduces image quality

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LimitCrown
Posts: 2
Joined: Fri Apr 07, 2017 7:22 am

0.96: Resizing images w/ "Use gamma correction" reduces image quality

Post by LimitCrown »

XnView: MP 0.96 - 64-bit
OS: Windows 10 - 64-bit

While I was resizing a couple of images in order to compare different resampling methods, I noticed that checking "Use gamma correction" caused things like hue changes mainly for some darker colors in the scaled image. Even if Nearest Neighbor is selected as a resampling method, the same issue will occur.

Step 1: Click "Resize".
Step 2: Choose any different width or height amount and check "Use gamma correction".
Step 3: Click "OK".

I'm thinking that when XnView MP converts the image to linear rgb values, before it performs the resampling and then reapplies the gamma compression, it may still be trying to use only 8 bits of precision for the linear rgb values instead of using a higher amount or using floating point values for the calculations. 8-bit precision isn't enough to represent the linear rgb values, so resizing images with the gamma correction option makes them less detailed than they were originally.
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