The Droste Effect is when an image recursively includes itself. The basic method is to insert a scaled copy of the image, but more interesting results can be acheived via conformal mapping.
Use Wiener deconvolution to deblur images. Wiener deconvolution can be useful when the point-spread function and noise level are either known or estimated.
Use the Lucy-Richardson algorithm to deblur images. It can be used effectively when the point-spread function PSF (blurring operator) is known, but little or no information is available
Use regularized deconvolution to deblur images. Regularized deconvolution can be used effectively when constraints are applied on the recovered image (e.g., smoothness) and limited