This thesis is concerned with the problem of determining pixel size for automated visual inspection(AVI) system. Pixel, an acronym for picture element, is a finite-sized cell partitioning the image. Three independent error sources - digitizing error, illumination error, and positional error - which have a close relationship with the performance of the AVI system, are considered. Assuming that digitizing error is uniformly distributed and illumination and positional errors are normally distributed, the distribution function for the error of measured lengths is derived when the length of a product is measured by the AVI system. Given the variances of the distributions for illumination and positional errors, the maximum pixel size, which makes it possible to inspect the length of a product with significance level α, is determined for two cases: ⅰ) a product is parallel to either the vertical or the horizontal, and ⅱ) a product is not parallel. The validity of proposed model is investigated by experiment. The literatures for applications of AVI system, mainly printed circuit board(PCB), IC wafer, and surface inspection etc., are also surveyed.
