1. A method of bright spot defect detection for a polarizer, said method to be performed by an inspection device and comprising the steps of: a) obtaining gray values for pixels of an image of a detected region, that contains a target spot, on the polarizer; b) obtaining a gray value variation score from the gray values obtained for the detected region, the gray value variation score being indicative of gray value variation among the pixels of the image of the detected region; and c) comparing the gray value variation score obtained for the detected region with a threshold value to obtain a comparison result, and determining whether the target spot is a bright spot according to the comparison result.