Effect of Defocused Image on Area Measurement and Error Amendment
离焦成像对面积测量的影响及误差修正

Phenomenon of defocus in machine vision, the effect of defocused image on aTo therea measurement was analyzed by the method of theory and experiment.The results of experiment show that the relative error is 31.3% when the object plane deviates 10 mm from conjugate plane.A method of amendment error was developed according to the relation between maximal image gradient and defocusing amount.The relation between maximal image gradient and defocusing amount was calibrated.The maximal gradient of image was calculated.The defocusing amount was deduced.And,the area of defocused image was amended according to the defocusing amount.After amendment,the relative error of image area is less than 3.8%,when the defocusing amount is within 10 mm.