1. A method for creating a sample image index table, the method comprising: extracting regional characteristics from a sample image; clustering the regional characteristics of the sample image into a plurality of nodes, respective regional characteristics of a respective node having a same degree of similarity, each node corresponding to a respective node identification; and establishing a sample image index table, the sample image index table storing a correlation between a first node identification of a first node of the plurality of nodes, an identification of the sample image, and a number of times that the respective regional characteristics of the first node appear in the sample image, the sample image index table further storing node identifications of the nodes of the sample image and a count of a number of the nodes in the sample image.