It appears to be a grayscale version of an image likely called
Patterns in Nature. The largest version of it I could find is
located here, and I've attached the terrible reconstruction I performed to do the image search, leading me to the minuscule information I could find on it.
Perhaps you'd have better luck posting in the UI Customization sub-forum, so I've requested that this thread be moved there where photo wizards
Tiggger and
Firedept might be able to work some magic.