Compare images - zoom at fixed place (do not reset images position when zooming)

[tol]

The only thing I'm missing from FastStone image compare is that XnView resets image adjustment position when we change zoom. For example, if we zoom 2 images a lot to see one object that is positioned in different places, we use right mouse click to position the object on both images to the center. and then compare it. Now if we zoom in/out even slightly, our adjustment is reset and we have to adjust again, and it takes very long at higher zoom. Faststone keeps adjustment, so if you move the image so that the object is in the middle on both images, you can zoom in and zoom out, and the object will always remain in the middle. This helps very much to zoom a lot and see what photo has better focus and less blurring.

[Gwenael Q.]

Hello,

I strongly support this request !

Thanks for listening

[tol]

I think it would also be useful to print zoom level for each image in comparison window when zoom is not equal 100%, because when comparing several images made with different focal length, it is useful to zoom every image separately so that the compared object would be approximately the same size on all images. Now when we zoom images in compare window, it is not possible to understand what extent of digital zoom was applied to every image. I think it would be easy to add a checkbox like "zoom level" after Grid/Info//CRC/H-stogram, and when we check this checkbox, a label showing the level of software zoom in percents appears in the corner of every image.

[xnview]

Thanks to your detailed description I can reproduce the problem.

[xnview]

This problem is supposed to be fixed in XnView MP 1.5.0 beta. Please check and confirm the bug fix here.

[tol]

I cannot test because the link goes to Windows download page and I use Linux version. I will be able to test it when there appears AppImage 64 bit, and here https://www.xnview.com/en/xnviewmp/#downloads we have XnView MP 1.4.5 only.

[tol]

So, I installed 1.5.5. 64 bit (Linux) 8-sep-2023. The problem doesn't seem to be fixed. How to reproduce:
1) take 2 similar images with some shift in view (attached test1 and test2).
2) compare them
3) zoom both images to some extent to see the train (for example)
4) move one image so that a selected object would be in the same place as in the other photo:

5) zoom in or out. the alignment fails, you need to reposition the image with every zoom in and out:

Test images:

[xnview]

you need to use CTRL to change behavior

[tol]

CTRL is for zooming one image only. But SHIFT-MOUSE WHEEL seems to work as it should. It is not obvious and not convenient. Maybe change behavior so that WHEEL should work the way the SHIFT-WHEEL works now? Not sure that anyone is happy by resetting the alignment position as it happens by default without pressing shift when zooming. I think if you want to keep the unaligned zoom, let it be SHIFT-WHEEL and aligned zoom only WHEEL. IMHO

[xnview]

CTRL is for zooming one image only. But SHIFT-MOUSE WHEEL seems to work as it should. It is not obvious and not convenient. Maybe change behavior so that WHEEL should work the way the SHIFT-WHEEL works now? Not sure that anyone is happy by resetting the alignment position as it happens by default without pressing shift when zooming. I think if you want to keep the unaligned zoom, let it be SHIFT-WHEEL and aligned zoom only WHEEL. IMHO

Sorry SHIFT. I can't change the behavior, many users had complaint about this...

[tol]

If some users want it the old way, maybe make it customizable in settings so that everyone will decide what default zoom method he prefers?