Abstract: A method of inspecting a flat panel display including inputting an image data signal into the flat panel display, obtaining an image displayed on the flat panel display in response to the input image data signal with a camera, extracting a raw brightness information corresponding to each location from the obtained image, calculating a fitting brightness information corresponding to each location through the curve fitting based on the raw brightness information, calculating a brightness difference corresponding to each location between the raw brightness information and the fitting brightness information, and detecting stain locations with the brightness difference beyond a predetermined permitted limit.