1. A method for extracting a region of interest from a digital image, the method comprising: from a set of training images, each training image in the set having a respective identified region of interest, with a processor, identifying a subset of similar training images, based on a measure of similarity between the digital image and the images in the set of training images, the identifying of the subset of similar training images comprising identifying the K nearest neighboring images, wherein K has a value of at least 10; and extracting a region of interest for the digital image based on the identified regions of interest in the subset of training images.