Abstract: A non-periodic dot output arrangement is taken in the low thickness region, and a periodic dot output arrangement is taken in the intermediate and high thickness region. In addition, error diffusion processing is made for all thickness regions. Small dots are produced in the non-periodic dot arrangement low-thickness region, and dot-concentrated-type dots are produced in the periodic dot arrangement intermediate-and-high-thickness region. Moreover, non-periodic dots are produced in the edge region of the image.

Abstract: An image processing method and an image processing apparatus for generating a binary image by binarizing the pixels of multlvalued tones are disclosed. An intended pixel, at least a pixel adjacent to the intended pixel and the density difference between the intended pixel and the adjacent pixel are determined. In the case where the density difference is larger than a predetermined setting, the intended pixel is determined as an edge portion. The binarization threshold for the intended pixel constituting an edge portion is set lower, the larger the edge intensity with the adjacent pixel. Thus, the edge reproducibility of the binary image after error spreading is improved.

Abstract: An image processing method is provided for reproducing multi-gradation image data in the form of a bi-gradation image as used particularly in a printer, a scanner, a copier, a facsimile, etc. The method comprises acknowledging a pixel arrangement around a target pixel through examining an on/off-state of each pixel of a binary form, calculating error correction data from the pixel arrangement, and carrying out a binary coding of multi-gradation image data. Accordingly, as the error data for a binary form of the multi-gradation image data is corrected depending on the density of its actual printed form, unstable artifacts generated in the reproduction of pixels can be suppressed during the binary coding.

Abstract: A multi-gradation image having a plurality of colors is binary coded by processing halftones in a pseudo manner. After the binary coding, an undesirable overlaying of colors on the image is eliminated so that image quality can be improved and also process load can be alleviated. A detailed process is this: Colors at a target pixel are binary coded, and the results are retained as data. When a color following the color already binary coded is processed, the retained data of the preceding color is referred to, thereby avoiding an undesirable composite black due to an overlaying of three primary colors on the same pixel. When the colors of an input image include black (K), this K is firstly binary coded at the target pixel, and when K is output, the other colors are halted outputting or a threshold value is set so that the other colors are not output. When K is not output, the other colors are binary coded in the order of higher density or higher visual sensitivity so that a quality image can be output.

Abstract: A method of gradation reproduction including (a) taking image data of a pixel subject to transaction as observing pixel data; (b) weighting the image data with an error diffusion matrix based on an error data calculated on a previously processed neighboring pixel of the observing pixel; (c) obtaining a data of pixel neighboring the observing pixel; (d) calculating a density gradient around the observing pixel from the weighted observing pixel data and the neighboring pixel data, and determining whether or not the pixel lies in an image edge region; (e) determining a dot size by comparing the weighted observing pixel data with a threshold value corresponding to an individual dot size, and selecting a predetermined smaller dot size if the weighted observing pixel data lies in the edge region; (f) producing an output of dot data by taking dot coordinates as a standard position of the observing pixel, if the dot size data is greater than a threshold value for coordinates determination after a comparison between t

Abstract: An image processor for preventing generation of an array of dots iteratively arranged and generation of a growth pattern of dots regularly arranged in an image after binarized. The processor includes a pixel data acquisition part for acquiring image data stored in an image memory on a pixel-by-pixel basis, and a dither matrix having energy focused dots positioned in the respective cells and arranged irregularly with a non-iterative property. The processor is adapted to acquire threshold value data from the dither matrix on the basis of an address of the image data and comparing the image data of the pixel unit with the threshold value data to output a predetermined binary signal.

Abstract: Dots defining the number of screen lines, of at least one color component of a plurality of color components, which number is different from that defined for each of other color components are generated on the basis of the screen method in which dot shape after binarization defines a halftone dot. A printing method and apparatus for generating binary data so that the size of such dots arranged concentrated to determine the number of screen lines differs among image constituting color components in the image after the binarization.

Abstract: An image processing method and apparatus for improving both gradation and resolution in a screening process. The apparatus comprises an image memory for storing multi-valued image data in pixel units; a pixel data acquiring portion for acquiring image pixel data from the memory; a threshold value matrix constituted by a density area by which dots of a high number of lines are produced and another density area by which dots of a low number of lines are produced; a threshold value data acquiring portion for acquiring from the matrix threshold value data corresponding to image data acquired by the pixel data acquiring portion based upon the image data address; and a comparator for comparing the acquired image data with the acquired threshold value data to thereby output a consequent binary signal.

Abstract: A non-periodic dot output arrangement is taken in the low thickness region, and a periodic dot output arrangement is taken in the intermediate and high thickness region. In addition, error diffusion processing is made for all thickness regions. Small dots are produced in the non-periodic dot arrangement low-thickness region, and dot-concentrated-type dots are produced in the periodic dot arrangement intermediate-and-high-thickness region. Moreover, non-periodic dots are produced in the edge region of the image.

Abstract: Binary coding is provided to a pixel of multi-grading to produce a bi-gradation image. Two adjacent pixels sandwiching a target pixel are determined. Then density differences between the target pixel and the respective adjacent pixels are found. When at least one of these differences exceeds a given value, the target pixel is considered to be part of the edge. When both of the differences are smaller than the given value, the target pixel is considered out of the edge. In the case of the target pixel belonging to the edge, a threshold value at the binary coding is set at a lower value than that of the case where the target pixel is out of the edge. Through the above procedure, an edge reproducibility of a bi-gradation image can be improved.