A method, system and product for image classification. The method comprising obtaining a set of encoding functions and signature values which corresponds to a set of class images, wherein each pair of an encoding function and a signature value corresponds to a class image of the set of class images, wherein the signature value is a value produced by applying the encoding function on the class image; obtaining an image to be classified to a class associated with a class image of the set of class images; with respect to each class image of the set of class images: determining a transformation from the image to the class image; and applying the encoding function using the transformation on the image to produce a value; and automatically determining a class to which the image is classified based on the values and the signature values.