The invention relates to an image segmentation and extraction method and solves the technical problems of low efficiency and poor effect during certificate image information collection in the prior art. The method comprises the following steps: a master control module obtains a color image and converts the color image into a gray image; the gray image is subjected to threshold filtering and converted into a binary image; a communicated region is calculated for the binary image; an edge point set of the communicated region is obtained; corner points of the communicated region are searched for; and according to the corner points, the long edge and the short edge of the communicated region are judged and an image of the communicated region is captured. The method is widely used in the technical fields of mode identification and image processing.