"High quality Zoom-out" lanczos-spline-bicubic filters don't work

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xmozg
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Joined: Fri Sep 24, 2021 3:31 pm

"High quality Zoom-out" lanczos-spline-bicubic filters don't work

Post by xmozg »

XnView: Version 0.99.1 64bits (Sep 23 2021) - thanks for new version with speed improvement.
OS: Windows 10 64bit

Bug: "High quality zoom-out" (image reduction) settings (settings -> view -> high quality zoom-out) for filters called lanczos, spline and bicubic don't work.

They all look like billinear. Only "High quality zoom-in" (image enlarge) works as expected.

This bug doesn't exist in Version 0.98.2 64bits (Feb 19 2021), before "2043: [New] Zoom out filter (Bicubic, Spline, Lanczos)" was introduced.

For some reason, Version 0.98.2 has "1958: [New] Zoom-in filter (Bicubic, Spline, Lanczos)" feature, but actually this feature is zoom-out (reduction).
Version 0.99.1 has "2043: [New] Zoom out filter (Bicubic, Spline, Lanczos)" feature, but actually this feature is zoom-in (enlarge).


Image compare lanczos4 algorithm for "zoom-out" at 99% level. Look only at 100% in image viewer. Version 0.99.1 at the right is blurry.
1xnview.png
2xnview.jpg

Test images from:
http://www.falklumo.com/lumolabs/articles/sharpness/
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xnview
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Re: "High quality Zoom-out" lanczos-spline-bicubic filters don't work

Post by xnview »

"High quality zoom-out" use always bilinear, the setting is for High quality zoom-in
Pierre.
xmozg
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Joined: Fri Sep 24, 2021 3:31 pm

Re: "High quality Zoom-out" lanczos-spline-bicubic filters don't work

Post by xmozg »

xnview wrote: Sat Sep 25, 2021 6:33 am "High quality zoom-out" use always bilinear, the setting is for High quality zoom-in
That's what I'm talking about. Just need to fix this bug, which in Xnview 0.98.2 was not and "High quality zoom-out" lanczos-spline-bicubic filters worked perfectly.
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xnview
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Re: "High quality Zoom-out" lanczos-spline-bicubic filters don't work

Post by xnview »

in 0.98.2, it was a bug
Pierre.
xmozg
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Joined: Fri Sep 24, 2021 3:31 pm

Re: "High quality Zoom-out" lanczos-spline-bicubic filters don't work

Post by xmozg »

xnview wrote: Sun Sep 26, 2021 7:55 am in 0.98.2, it was a bug
I dont know, how it is bug, if:
xn5.png
Version 0.98.1, where high quality lanczos-spline-bicubic filters was officially introduced, shows lanczos zoom out perfectly.

Only starting with 0.98.3, when high quality lanczos-spline-bicubic "zoom out" was introduced, also bug was introduced, which destroy ACTUAL high quality lanczos-spline-bicubic zoom out and replaced it with high quality lanczos-spline-bicubic zoom in. In photography sharp zoom out is much more important, than sharp zoom in. Bicubic-spline-lanczos algorithm recommended for zoom out. And billinear recommended for zoom in. Xnview not just has this bug, but works not as expected by image editors and in pro photo, using resource-cheap billinear zoom out as 1990-early 200X programs.

Please fix this bug, or return back destroyed "Bicubic-spline-lanczos zoom out", so xnview will have Bicubic-spline-lanczos algorithms for both zoom in and zoom out. Version 0.98.2 is latest, which I can use. 0.99.1 is blurry and ugly, it and newer versions will be abandoned by me and other users (to which high quality matter), until bug will be fixed.
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