PSNR

PSNR is a lightweight, portable, handy, third-party software solution that was designed to provide you with an easy way to determine the peak signal-to-noise ratio (currently known as PSNR) between two different images on your computer.

In order to operate the application in the manner that was intended, the two loaded images must have the same dimension. After you load the two images that are identical in size, the application computes the PSNR ratio, which comes in handy for evaluating the picture quality after compression, and displays it for you to see and use as you want.

As specified above, this application is portable, meaning that you don't need to install it on the target computer, as simply launching the executable that you've downloaded grants you full access to its whole array of features. More so, you can launch it from removable storage media such as USB flash drives or external HDDs or SSDs without worrying about it creating additional files or folders on your PC or tampering with your Windows registry entries.

Its interface is quite simplistic and intuitive. As said above, all you have to do is load the first image by using the "Image 1" button, then load the second one by using the "Image 2" button, and you're all set.