A method of inspecting a liquid crystal panel and determining the type of defect. Each part of the liquid crystal panel is extracted and inspected by comparison with an extracted reference part. The parts to be inspected may be found based on the location of previously found parts or by examining a plot of the density in the image. Vector data from a part that is known to be defectless is used to extract the reference part. Alternatively, the contour of a reference part may be determined by analyzing the vector data which was obtained for the parts to be inspected. The type of defect is determined by classifying the defective part according to characteristics of the part's image (e.g., brightness of the pixels) as compared with parts having known defects.