MP 1.11.7 opens images at slightly wrong size

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Just reporting
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Joined: Mon Oct 05, 2026 11:19 am

MP 1.11.7 opens images at slightly wrong size

Post by Just reporting »

Hello! I'm using XnView MP 1.11.7 on Windows 10. Could not update it recently due to either installer or the app complaining about some missing .dll, which never happened before (so I rolled back, that's beside the point for now, I'll retry, maybe with a newer version).
My settings are such that it opens in windowed mode, only reduces dimensions of large images, therefore should show anything fitting within the window unchanged. However, I accidentally pressed the key to see the image at at 100% zoom, which should have produced no effect, but it jumped a little. Turns out, newly opened images get slightly reduced in size by skipping a single column and/or row of pixels. Sometimes skipped rows/columns are in the middle of an image, sometimes it's at the leftmost column.
A key to show at 100% (pixel perfect) zoom jump resets it to a (possibly) correct size.

I tried this with either with no instance of the software running, other instance running, or by moving to the next image in the folder. Also, from browsing mode. I tried this with JPEG, PNG, WEBP and JXL. Happens each time.
There were a few exceptions though. The bug manifested on 829*918 and 1024*1024 pixels images. However, 1549*1774 and 520*362 did not produce this bug. Couldn't test all possible sizes, just some random I had at hand.
I'm on 4K screen resolution. No HiDPI settings were activated.

It may've been a little verbose, it's the first bug I'm reporting here.
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xnview
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Re: MP 1.11.7 opens images at slightly wrong size

Post by xnview »

Just reporting wrote: Mon Oct 05, 2026 12:01 pm Turns out, newly opened images get slightly reduced in size by skipping a single column and/or row of pixels. Sometimes skipped rows/columns are in the middle of an image, sometimes it's at the leftmost column.
could you send a screenshot
Just reporting
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Re: MP 1.11.7 opens images at slightly wrong size

Post by Just reporting »

It's one such example, this time not displaying final bottom row of pixels or so.

Important! I just found something else. I set small images to be upscaled using the bicubic filter, which I didn't do before, and which should not have affected small images in any way, since I selected to only downsize large images!
I did it just now, I never notices anything weird before. Also, it was a lucky accident that I pressed the wrong key.
So, I have had Bicubic resampling selected for both upscaling and downscaling. Once I leave Bicubic only for downscaling and nearest neighbor for upscaling, the bug disappears.

Sorry, didn't check all other up- and downscaling filter combinations filter.
Update: I tried each setting for upscaling filter. Only nearest neighbor and Bilinear do not cause the bug. Each one of the following do:
Bicubic, Spline 16, Spline 36, Lanczos 3, Lanczos 4

Attached are before, after and the "offending" image (there are many like this).
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user0
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Re: MP 1.11.7 opens images at slightly wrong size

Post by user0 »

Just reporting wrote: Mon Oct 05, 2026 12:01 pm I'm on 4K screen resolution. No HiDPI settings were activated.
No HiDPI settings in XnView? what is your win dpi scale?
Just reporting
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Re: MP 1.11.7 opens images at slightly wrong size

Post by Just reporting »

Can't give an exact figure now. It's 31.5'' @ 3840*2160, so you can get a rough estimate from it. I have 150% Windows scaling turned on, plus HDR enabled if that is relevant to reproducing the bug.
I mean, there's a HiDPI setting right there where you set scaling for XnView MP. What it seems to do is scale according to Windows scaling setting, so you never have 1:1 mapping to your actual screen pixels. I want to be able to have as tiny pixels as possible, so this settings is disabled.
Maybe I'm getting it wrong. But it appears that it blows up pixels and makes small images 150% times bigger, and any images have blown up pixels with that setting on, including downsized huge images. That all it does for me. I don't wanna be switching my Windows scaling settings back and forth to be sure of all possible side effects, I got this set up exactly the way I want, and some apps didn't catch on with Windows scaling immediately for whatever reason.
The whole point upgrading to 4K was to have finer details, so this setting negates all the gains in resolution. To have small pictures larger, I enabled auto upscaling of small images for a while, selected Bicubic, then disabled auto upscaling (and left Bicubic selected, it shouldn't have affected any small images ). And discovered this anomaly. Hardly noticeable in 4K, but still.
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user0
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Re: MP 1.11.7 opens images at slightly wrong size

Post by user0 »

Just reporting
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Re: MP 1.11.7 opens images at slightly wrong size

Post by Just reporting »

user0 wrote: Mon Oct 05, 2026 7:06 pm same issue as here:
1.8.0 - viewer - antialiasing - issue with dpi scaling
Not the same. I have zero issues with upscale being set as bilinear or none. I have 1:1 image pixels to screen correspondence, as expected, a long as it fits in the window - precisely to my settings. Also, if I press the key to view in 100% zoom with other upscale filters enabled, images snap to perfect 1:1 size.
Any of the upscale filters should do nothing, as long as the image fits in the window (or fullscreen), as was selected (I chose only to downsize larger images).

Update: fullscreen mode is affected the same way by the bug. Having HiDPI checkbox checked seems to negate the effect (didn't check many images though).
Just reporting
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Re: MP 1.11.7 opens images at slightly wrong size

Post by Just reporting »

Here's a more explicit example. 1 pixel thick central horizontal line disappears. Both are denoted as being at 100% zoom. Both are freshly opened (no instance of the app running). The only difference is that in the "before" I had upscaling set as Buicubic, and in the "after" it's set to none (nearest neighbor).
It can happen in the vertical or horizontal dimension, or both.
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