I can’t do it with my glasses on. So, that means I need to get close to the monitor because I’m near-sighted, which means I need to make the image smaller. Once I do all that, I can see them.

I don’t know what’s changed, because the first time I saw one was as a print displayed at a mall, probably 35+ years ago.

Some are easier to see than others. I find the ones with a bigger pattern image like wallpaper, rather than the small dots are easier.