It’s just one of the many tricks that Kandid, the funky java program does. This one was pulled from its Affine IFS Grayscale magic hat. If you look at enough of these they start to get irritating, but sometimes they are very startling and surreal like this glowing cloud in a black sky.
Here’s another that has no particular feature of interest but has a strange ghostlike, appartion appearance. To me it looked like some Roman galley with oars sticking out and military banners held up. But it also has a passing resemblance to a building filled with scaffolding and rebar and about to have concrete poured into its forms — in a nightmarish sense.
And everywhere –the mysterious vapours.
It gets crazier. You can “breed” the images and mix their “chromosomes” together! It’s called Genetic Art. I call it The Island of Dr. Moreau.jar (Java ARchive).