1. A method for image comparison, comprising: reading from a memory in a computerized image processor a source image and a target image; segmenting the source and target images, using the image processor, into respective pluralities of source and target arrays, respectively comprising source and target array elements, each array element comprising a matrix of one or more pixels from a respective image, each of the source arrays having a respective position in the source image, and each of the target arrays corresponding respectively to one of the source arrays based on the respective position; applying an asymmetric warping process between each of the source arrays and each of the respectively corresponding target arrays so as to compute respective array similarity scores; and combining the respective array similarity scores so as to compute an image similarity score of the target image with respect to the source image.