In order to resolve conflict of measuring speed and precision

a novel measurement was proposed to detect approximate defect positions by image recognition and to measure accurately the three-dimension profile by laser displacement sensor.The image capture and data acquisition equipment for scanning measure was designed for spherical surface.The image background noises were reduced by low-pass filtering algorithm based on analyzing image features.According to the difference between high and low envelope curve constructed by maxima and minima on the current processing image

the approximate defect positions and region were determined.The defect edge was approached iteratively based on Snake model.The data processing and defect representations of the three-dimension profile were discussed.This method outperforms traditional image segment methods at self-adaptation to complicated background images.Moreover

the measuring system can measure automatically and reliably to detect surface defects.