finallywe can combine the two images to have the center in sharp focus and the edges softer ringed mh stretch(im* ( - )*im now that you know some of the basic techniques of filtering imagesyou can build upon this to generate new filters it is more of an art than science after this point pattern recognition when classifying imageswe start with large rectangular array of numbers (pixel valuesnowadaysmillions of pixels are common we could try to feed all these numbers as features into the learning algorithm this is not very good idea this is because the relationship of each pixel (or even each small group of pixelsto the final result is very indirect insteada traditional approach is to compute features from the image and use those features for classification there are few methods that do work directly from the pixel values they have feature computation submodules inside them they may even attempt to learn what good features are automatically these are the topics of current research