The goal of an edge detection algorithm is identifying pixels that
belong to an edge of an object in an image …
The rest of the sentence should say something along the lines of "and point them out by …" – but "point out" seems too informal.
Pointing out is also the wrong phrase because the pixels don't need to actually be "displayed" to some user at all, and most likely will just be used as information for some next step.
So the word/phrase I am looking for should not imply something visual, but informative.
Best Answer
Flag might be useful. It's a bit of an 'old skool' programming term but seems appropriate.