1. A method comprising: generating first and second pseudorandom numbers; extracting a first feature of an image based on the first and second pseudorandom numbers, wherein extracting the first feature of the image comprises: identifying a location of a region of the image based on the first and second pseudorandom numbers; and computing an average of pixels of the identified region; determining whether a classification for the image is known; and in response to a known classification of the image, updating a classification model used to classify a second image.