1. A method for generating a thumbnail of an image, comprising: filtering an image to obtain an edge intensity value for each pixel point in the image; sliding a preset rectangular box on the image to perform a search and, at each searched position, calculating a distribution value of information amount in the rectangular box according to the edge intensity values of the pixel points therein; and selecting the rectangular box with the largest distribution value of information amount, and intercepting content of the image corresponding to the selected rectangular box to obtain a thumbnail of the image.