In the process of industrial inspection,the collected images can be divided into clear processed texture and blurred according to the resolution.A vernier caliper jaw gap detection method based on the improved Otsu algorithm was proposed.Based on the quadtree theory,the problem that the Otsu algorithm did not work well when there were fewer target pixels was solved.The surface texture of the vernier caliper under the high-resolution image is clear,it is difficult to distinguish the texture feature and the gap feature.To resolve this problem,the collected gap images were preprocessed,and their thresholds were calculated by using the improved Otsu,and the edge detection,gap feature extraction and straight line fitting were performed to complete the automatic detection and accurate identification of the vernier caliper gaps.A set of experimental equipment was established,and the gap detection method with clear texture was used to verify the effectiveness of the gap detection method.The results show that the by using the proposed algorithm,the accurate automatic extraction and detection of the gap edge can be realized,and the detection time of a single picture is about 400 ms,which meets the requirements of industrial real-time detection.