Finding repeating patterns/images in images

A number of methods come to mind:

• Fourier Transformation of the image
• Wavelet Analysis
• Autocorrelation

I'd start with fourier analysis: Any shape repeating in a regular pattern in the image creates a very distinct spatial frequency spectrum: One major frequency and some harmonics.

I'm not sure if this is what you're looking for, but I suggest searching for "Texture based segmentation". Take a look at this bibliography, for example: http://www.visionbib.com/bibliography/segment366.html