| 摘要 |
PURPOSE:To exclude a false zero crossover, and to realize perfect edge detection by obtaining a zero crossover previously by using a <2>G filter, and using the output value of a G filter at this point. CONSTITUTION:In an edge detecting part 13, the zero crossover is obtained from the <2>G (Gaussian Laplaciian operator, <2>: second order differential operator, G:Gauss function) filter, and simultaneously, the result of a G ( : first order differential operator) filter at the zero crossover is obtained and compared with the result of the <2>G so that a true zero crossover is discriminat ed. Namely, all the output values of the G filter at the true zero crossover become positive or negative large values, and are different from the output value of the G filter immediately before in their signs. On the other hand, the output value of the G filter at the false zero crossover becomes the value approximately near to zero, and besides, is different from the output value of the G filter immediately before in its sign. Thus, the false zero crossover can be excluded, and only the true edge exiting in a picture can be detected, and in addition, each of the pictures with different intensity characteristics can be expressed separately. |
