Digital Image Processing Technology Applied Research, Testing Of Dimensional Tolerances

Study to determine the dimension and tolerance of the measured object by using computer image processing technology was done.For the collected matter image processing was divided in steps: firstly, methods including Histogram Equilibrium, Wavelet Transform etc. were used to eliminate the noise in the image; secondly methods including Threshold Division, Mathematic Morphology, Edge Extraction were used to obtain division matter image; thirdly Hough Transform was used to detect the line or circle in the brim of the measured matter and finally the dimensions and tolerances could be calculated based on the line or circle equations.Glass medicine bottle and electric motor frame were chosen to be studied as they are typical representatives in industry. For bottle image, lines in the matter brim was detected by means of Hough Transform and then dimensions and perpendicularity tolerance were obtained. For motor frame, circles in the matter brim was detected by means of Hough Transform and then concentricity tolerance was determined.A novel no touch measuring method for traditional products was put forward and a precise model of Direct Linear Transform (DLT) was presented for the aberration in the images occurred at every turn. Rectangle mark tag and location parameter are no longer needed in this algorithms. A method of tolerance reckon by curve equation was also provided. In order to raise the operation speed Hough circle detection method was improved. In the meantime circle detection method to images with more than one circle was applied, so that the concentricity calculation is possible.