A Canvas Made of Pixels
>> A fun (but impractical and frustrating) variant of this feature is to have the image change as soon as the viewer looks away. So you’re looking at a painting, glance away to another room, and look back to find a new painting hanging on the wall.Re this comment. There is this thing called "saccadic masking", the gist of which is that we are effectively blind while our eyes move from focusing on one position to the next. Depending on the "distance" (angle) traveled by the eye, this can last up to tens of milliseconds. Enough time to do some cool stuff!One of the studies that conclusively showed this effect, a fairly long time ago, had participants wear some elaborate headgear that allowed the researchers to track where the eyes of their participants were looking at. They had them look at a standard sentence like"the quick brown fox jumped over the lazy dog",but with a twist! Every word in the sentence was masked, except for the word the participant would be focusing on at that moment. So if he focused on the word fox, the screen would show"xxx xxxxx xxxxx fox xxxxxx xxxx xxx xxxx xxx".Whenever the system detected a saccade by the eyes, they would recalculate which word the participant would be looking at (e.g. switch to dog), and changed the display of the screen accordingly, now showing"xxx xxxxx xxxxx xxx xxxxxx xxxx xxx xxxx dog"Participants were asked if they noticed anything strange about the sentence, but they reported there was nothing strange about it! (Disregarding having a heavy set of mirrors strapped to your head).My point: If you were able to detect saccades of the eyes, and relatively accurately calculate their position, you could  have the region of the image that's unattended be colourful noise, the theory says that your visitors would be none the wiser (of course this would break down with multiple people looking at the same image)Even cooler: procedurally re-generate parts of the image that are unattended, so that you're looking at an ever shifting image, but wouldn't quite be able to pin down what's happening. Similar to this video: https://www.youtube.com/watch?v=ubNF9QNEQLA