The invention relates to a system for sequentially analyzing each data point representing a digitized video line image and modifying the point to improve the quality of the image based upon an examination of surrounding data points. Specifically, data comprising a digitized scanned image with each point represented by a one bit digital signal is stored such that a matrix of data is continually supplied to a data multiplexer. The data multiplexer selects the portion of the matrix data to be compared to predetermined criteria to determine whether or not the data point being analyzed should be changed to improve the quality of the image.

A digital circuit for detecting changes in the gray scale of scanned images is disclosed. Each line of video information produced by scanning the image is digitized. Each digital sample is compared to digital samples delayed a predetermined amount to generate a difference signal which is indicative of a change in the gray scale having a component perpendicular to the direction of scan. The digitized samples of the video signal are also stored in a memory having a capacity sufficient to store data representing a plurality of scan lines with a typical memory having a capacity for storing digital information representing eight scan lines. Selected digital samples from the stored data are compared to samples of the line being scanned to detect changes in the gray scale having a component parallel to the direction of scan. These changes in the gray scale are combined to generate a signal indicative of the central portion of the change in the gray scale of the image being scanned to drive a printer to generate a line drawing with the position of the lines corresponding to the central portion of the changes in gray scale of the scanned image.

A picture printing device and method for printing pictures using a main scan and a sub scan. A first comparison means counts the number of picture elements in a main-scanning direction and compares that number with a first value preset in the first comparison means. A second comparison means counts the number of scanning lines in a sub-scanning direction and compares that number with a second value preset in the second comparison means. A printer records predetermined signals in response to combinations of the outputs of the first and second comparison means.

A method and apparatus for modifying an image data signal has a serial channel for obtaining a desired number of current M-bit patterns from the image data. Unique bit patterns are recognized in the current bit patterns, and new bit patterns are generated, each being specific to the detected unique bit pattern. The current and new bit patterns are combined in a predetermined manner to modify the image data as desired. For example, if the unique bit patterns are recognized as dark images on a leading edge of an image, the new bit patterns are generated and combined with the current bit patterns to lighten the image, particularly at the leading edge to improve stripping of the print media on which the image is printed from a fuser roll of the printer.

An image processing system comprises a television-type camera for line-by-line scanning an article to generate a video signal representing an image of the article. The video signal is applied to one end of an even number 2n of series-connected delay elements whose time delays are symmetrical relative to the mid-point of the series, and the amplitudes of the underlayed and successively delayed video signal are normalized so that all such amplitudes are equal when the video signal over the total delay period represents a constant intensity portion of the image. A signal D is formed representing the difference between n times the amplitude of the video signal at the mid-point of the series of delay elements and the sum of the amplitudes of the video signal at the input of the series of delay elements and at the output of each delay element except the delay element whose output is at the mid-point of the series. The signal D defines the positions, in the direction of line scanning, of edges between contrasting regions of the image.