The creator of the image is the copyright owner. But, there are a few tricks.
- If a program can be used to create the image, and does so in a completely automatic manner, then the creator of the program owns the copyright.
- If some work is needed to create the artwork, then the person who did the work to create the image owns it. (Think, if a person draws a picture in photoshop, they own it). In this case, if a person creates a cool formula to create the image, then they would own it.
- If a person can generate an image on their own that looks similar, they they own it.
Of the two images, I'd say the first one is generic enough that many people no doubt have created a similar image, and it would be fairly safe to use.
The second shows some real creativity. Anyone who could create the right formula could own the copyright to the image they generated. If a person finds a similar formula, then they own the copyright to produce their new image.