Cosine integral images for fast spatial and range filtering
Elhanan Elboher, Michael Werman · 2011
Non uniform kernels is important for many image processing algorithms. However, for large kernel sizes the filtering can become computationally expensive. We introduce cosine integral images (CII) which represent a large set of spatial and range filters, based on their frequency decomposition. The filtering requires a constant number of operations per image pixel, independent of filter size. We make use of CII to compute the Gabor filters, whose complexity is for the first time a constant O(l) operations per image pixel. We also improve previous constant time approximations of spatial Gaussian smoothing and bilateral filtering.