Ranking structural ten pre- - to matching manner

摘要

PURPOSE:To shorten an operating time and to reduce the number of operations by using a template area in terms of a hierarchized structure to set a threshold value for each matching step and detecting all candidate points having coincidence degrees larger than the threshold value in a matching state of each step to select the candidate point of the next step based on the positions of said candidate points. CONSTITUTION:The sampling rate of a template image is set one image element for every 2N-M image elements in the X and Y directions for a template area M. Then the area M is shifted by an image element within a candidate point area and at the same time template matching is carried out with a template image itself. The coincidence degree is calculated at each position and the minimum coincidence degree is defined as the threshold value TM. If a genuine coincident point is included in an rectangular area close to + or -2N-M-1 image elements in both X and Y directions of a certain candidate point, it is considered that the coincidence degree of said candidate point is larger than the threshold value TM. When the coincidence degree of the candidate point is smaller than the value TM, it is decided that the genuine coincident point is not included in said rectangular area. Thus it is decided that the candidate point whose coincidence degree is maximum in the final step is equal to a genuine coincident point.