METHOD FOR NOISE-IMMUNE GRADIENT SELECTION OF OBJECT CONTOURS ON DIGITAL HALFTONE IMAGES Russian patent published in 2019 - IPC G06K9/48 

FIELD: data processing.

SUBSTANCE: invention relates to image processing and can be used in photo, video, optical-location and optical-electronic equipment when solving tasks of pattern recognition by their contours on images. Method's essence consists in that, taking into account the noise level of the image, the smoothing coefficient is selected, coefficients of smoothing cubic B-splines are calculated along each line and each column of the image. Then two matrices G^x and G^y component of the brightness gradient at each point of the image by summation of smoothing parabolic B-splines with coefficients of smoothing cubic B-splines found earlier for rows and columns. Further, a brightness gradient module is determined at each point of the image. After that, contours of the object are formed by converting a brightness gradient module, during which elements on the new white matrix are selected with black colour, the modulus of the gradient for which in the image coordinates exceeds the transformation threshold.

EFFECT: high rate of extracting contours of halftone images in conditions of pulse interference.

1 cl, 3 tbl, 5 dwg