1. A computer-implemented method for merging separated pixel blocks into an integral image of an object, the method comprising: obtaining an image captured by an image obtaining device from a storage device; performing binary image processing on the obtained image to obtain a binary image; finding each pixel block in the binary image whose area is greater than a first preset value; recording a position and a size of each found pixel block, and storing the position and the size of each found pixel block in a data structure; and calculating a distance between every two pixel blocks in the data structure in sequence, and merging the two pixel blocks if the distance between the two pixel blocks is less than a second preset value, so as to generate the integral image of the object.