Systems and methods herein provide for reduced computations in image processing and a more efficient way of computing distances between patches in patch-based image denoising. One method is operable within a processing system to remove noise from a digital image by generating a plurality of lookup tables of pixel values based on a plurality of comparisons of the digital image to offsets of the digital image, generating integral images from the lookup tables, and computing distances between patches of pixels in the digital image from the integral images. The method also includes computing weights for the patches of pixels in the digital image based on the computed distances and applying the weights to pixels in the digital image on a patch-by-patch basis to restore values of the pixels.