Pixel perfect diff
We use a custom algorithm to compare screenshots. It allows detecting vertical shifts so you won't get the whole page highlighted because of a little shift in the header.
Meanwhile, we still do diffs with pixel by pixel comparison tool ImageMagick. You can see results in the UI by using the toggle.
![Diffy Pixel Perfect toggle](/sites/default/files/2022-06/diffy-toggle-pixel-perfect.png)