One of the readers (thank you, Peter!) reminded me that there is a version of a blink comparator that all of us are exposed to perhaps every day: many photo editing apps – Apple Photos, Darkroom, Aphera, I imagine others – allow you to quickly compare the photo as-shot and with your edits. Sometimes it’s a tap, sometimes an onscreen button, and in the case of Lightroom it is a backslash key. Here’s that feature on a color graded photo with some dust removed:

But these blink comparators are smart. If you e.g. rotate the photo, the comparison will be with the original also rotated so the pixels still map to each other 1:1 – even if you rotated the photo as the last step in your editing process:

I think this is a brilliant example of understanding the spirit of a feature rather than its letter. A naïve blink comparator would show an unrotated photo, but in this way it would cease being a blink comparator.