Method of circle detection in PCB optics image based on improved point Hough transform

The cause and method of pre-treatment of PCB optics image in the optics image detection were given at firstly; The method of circle detection based on traditional Hough transform (THT) was analyzed, and it's shortcomings were given; To overcome these shortcomings, a method which calls piont Hough transform (PHT) to evaluate the parameters of the circle was adopted, and it's basic principle was analyzed in detail., It has some advantages such as small amount of data, high precision and fast speed, but it has some shortcomings also. Accordingly, a method for evaluating the parameters of the circle based on improved PHT (IPHT) was proposed, which features smaller amount of data and faster speed than the method of the circle detection of the PHT; At last, the result of experiment for the circle detection of PCB optics image verified the superiority of the method.