Abstract
A new image processing technique to apply an approximate plane of brightness has been proposed for inspecting defects of irregular pixels in a CCD image captured in proximate front of a LCD panel. The technique is capable of making automatic and speedy detection of defects, by reciprocally comparing the gradient of an approximate plane, which is derived from the brightness of each pixel in a small area divided into the identical section with a reference image. By exploiting the difference of the gradients in distinguishing the section associated with defects, there are a few characteristics as compared with the typical image processing techniques such as the differential and the template method. One is robust to noises that have effect upon the captured image from electric circuits constructing a camera itself. The other need not perform the template processing by a particular operator to emphasize a kind of defect in implementing image processing. Another is able to reduce the processing time because a captured image can be treated at a stretch without regard to kinds of defect. In this paper, we experimentally make it clear that the technique is able to detect not only a dot and a line defect of high variation, but also non-uniformity defects of comparatively low variation in brightness of pixels. Experiments with pseudo-defects represented in an actual LCD panel demonstrate that from the results obtained in 3colors×0.12seconds of processing time, the technique is able to be applied to a system for implementing defect-inspection of a certain uniformity level in real time.
