Phase scrambling is typically used to retain the low-level image properties of images, but to make the content of the image less visible. This can serve as a baseline condition for localizers of object-selective brain regions. It can also be used in experiments where the visibility of stimuli is reduced. Here, the Matlab image Mandrill is partially phase scrambled. The code is found here.
Using a similar approach, nice clouds can be created. These clouds can serve as a basis for the Anderson & Winaver illusion. Here, both Kermits have the same luminance, but they look completely different. The code for making clouds and such illusions is found here.