Basically I compress images to reduce sizes, but for JPEG this will lead to quality loss.

For now, I open Windows photo viewer twice, one for original images and one for compressed one, maximize the windows and switch between them by Alt + tab shortcut.

But this is quite inconvenient, in that I must first zoom in on both images in the same scale, and drag them so both images are showing exactly the same position to make it easier to compare same part.

Is there a Windows application for comparing two images the easier way?

Maybe something like this: Run the app and open multiple images in the same window, and two images are overlapped one over another. and I can toggle between before & after images by clicking some icon or keyboard shortcut.

So obviously I am not looking for an app that calculates the difference mathematically, but I just want to see if the compressed images are visually in good enough quality by looking right at it.

  • Are you resizing as well, or just compressing ? Mar 23, 2023 at 13:18
  • IMHO the definition of "visually in good enough quality" is very personal, and quite hard to find some software that agrees with your visual - and any software will use a mathematical model to do that
    – LuC
    Mar 24, 2023 at 13:15
  • How about you use PNG or TIFF with a loss-less compression type. Will the files be as small probably not, but they will be reduced in size. A number of pictures type support multiple compress types, although I don't have a list handy. Then you don't have to compare anything. LZW is loss-less.
    – cybernard
    May 1, 2023 at 16:48

3 Answers 3


XnView MP kind of does what you need, but not 100% as you descibed.

You can select few images with Ctrl, then select Tools -> Compare.... Then you can either view them side by side by default (they're in sync when it comes to zoom etc.) or select Use tabs at the bottom and switch between each tab, which is kind of like our overlap requirement, but not fully.

In general many of Windows gallery apps have this a kind of feature, so may be worth to check some other ones out and compare to see which one lets you work in the fastest way.

  • That's a good app but in my use case, a bit overkill since it is focused on editing photography like adobe photoshop or lightroom by the look of it which I never do. but the zoom sync is very useful feature, I will look for an alternative but if nothing better is found, I will consider using this :) thanks
    – medukia
    Mar 23, 2023 at 2:33
  • It's not focused on editing, it's a typical image gallery app. It has some editing and other options, but they're rather basic. The main focus is image management though.
    – Destroy666
    Mar 24, 2023 at 19:28

I think Beyond Compare might work for you. It is reasonably cheap and is a comprehensive folder/file comparer.

If you have the files in different folders with the same names then you can use the folder view and double click on the image you want to examine.

Image comparison example

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Folder compare example where I am comparing original images with compressed ones.

enter image description here

  • I think this app is of different use. my primary concern is not what the actual difference is, but how different they look to the naked eye :)
    – medukia
    Mar 24, 2023 at 10:36
  • It does both, and I am using it for exactly the same purpose. To compare the compressed version with the original, to see if I should recompress it with different parameters. Mar 25, 2023 at 6:18

Maybe you can try FastStone Image Viewer. It has a compare option:

Compare images side-by-side (up to 4 at a time) to easily cull those forgettable shots

You select two images and click the Compare option (on the toolbar, right-click menu, or the keyboard shortcut p) and it opens the two full screen (with auto-fit option for the images.)

  • this is almost a perfect match for my use case. it even supports layering by clicking on green left arrow icon between two images. maybe it would be better if It supports custom context menu, so I can just select two images from windows explorer and directly jump to compare window.
    – medukia
    Mar 25, 2023 at 2:41

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