Abstract: A process for testing the tolerances of bores made by laser pulses records a matrix image of the bore region during each laser pulse and evaluates the matrix image to determine the average bore diameter. Compliance with the required tolerances can thereby be achieved during the boring operation. The evaluation of the matrix image is made by optically forming a half tone, dot matrix, mosaic image of the bore and its surrounding region, adding gray scale values of the dots in the columns and rows and differentiating the column and row totals to produce spaced maxima for the rows and columns. The distance between the spaced maxima in the rows and columns represents the diameter of the bore in the direction of the rows and columns respectively.