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.