Abstract: This invention provides an image processing method and apparatus. Two types of edge emphasis processing operations having different degrees of edge emphasis are performed for image data of a read original. When paper quality of the original instructed by an operation unit is recycle paper, the edge emphasis processing having a smaller degree of the two types of edge emphasis processing operations is selected. The selected (multi-value) image data is binary-converted, and the binary-converted image data is output, thereby obtaining good image quality with respect to the read original regardless of the paper quality of the read original.

Abstract: A method of color halftone reproduction with reduced moire patterns and simplified calculations of color densities is disclosed. The method entails dividing a reproduction surface into an array of abutting halftone cells having centers aligned at a screen angle, preferably 45.degree. , with halftone cells in adjacent rows. The halftone cells each cover an area of M abutting horizontal dots long by N abutting vertical dots wide. The various system colors are applied to the pels, as required, in color patterns centered within the halftone cells. The patterns overlap one another to adjust the hue of the reproduction at the halftone cell location to the desired hue. The method is usable with permanent reproductions, such as printed paper, or with transient reproductions, such as the image on a CRT screen.

Abstract: The present invention is a method and apparatus for processing a color document for moire-free printing, the color document including a plurality of color separations each defined with a set of image signals representing optical density with m possible density levels, while a printer is capable of rendering density with n density levels. The invention employs a spatial resolution scaler to produce m-bit signals at a spatial resolution that is a function of the halftone screen angle, base dot pitch, and desired halftone cell size. Subsequently, the m-bit signals at the desired spatial resolution (frequency and angle) are halftoned to produce n-bit signals that are printed with a raster output scanning-type printer suitable for printing at selectively variable spots per inch in both the fast and slow scan directions.

Abstract: A full-color image printing method and apparatus operate to form mono-color toned images of individual color components using multiple, e.g., four, mono-color imaging units provided in correspondence to the color components and single-lined screen processors provided in correspondence to the imaging units, and overlap the mono-color toned images sequentially to produce a full-color image on a sheet of print paper. The screen angle is made different among the mono-color toned images and the line pitch of the screen is made virtually equal for all mono-color toned images with the intention of retaining a high-grade color quality and preventing the degradation of picture quality such as a degraded tone quality.

Abstract: An image processing system for preparing a color document for printing, each discrete area or pixel in the image described by a signal having a number of possible states greater than can be rendered by a selected printer, in which each separation of the image is halftoned, with at least one of the separations processed with a non-periodic halftoning method, and at least one of the remaining separations processed with a periodic pattern. Preferably, in a printer printing with colorants approximating cyan, magenta, yellow and black, one of the non-yellow separations is processed with the non-periodic halftoning method.

Abstract: A method of halftone printing in four colors using, for cyan, magenta and black, halftone screens that will result in screening angles of 15, 45 and 75 degrees, as is the standard process in the art, and a halftone screen for yellow that will result in screening angles of 0, +60 and -60 degrees. This combination will diminish the 2 color moire patterns that result from the interaction between the yellow and one of the other colorants. The 0 and + or -60 degree screening angles are generated by using a screen that produces a four-centered cell having dots that are spaced to form hexagons, when the nearest neighbors of a central dot are connected by lines, as opposed to the conventional trapezoidal orientation.

Abstract: A picture image color separating apparatus to be used when block copies for dyeing use are made in a dyeing business, wherein a region the above described other representative color occupies may not exist on a straight line connecting the above described adjacent two representative color positions on the color space when the other representative color exists near the adjacent two representative colors on the original picture image from among a plurality of representative colors selected by the given procedure by the representative color selecting portion from the illustration inputted from the picture image inputting portion, whereby noises by the above described representative color are not caused on the boundary of the above described adjacent two representative colors.

Abstract: In a dot image discrimination circuit, a dot image in an area composed of many multi-tone pixels including a central pixel is discriminated. A pixel (change point) at which the density of the image data is prominent in a first direction is detected in a plurality of pixels. Then, it is inspected if change points exist continuously in a second direction perpendicular to the first direction. The change points are counted in an area of a prescribed size around the central pixel, but some change points existing continuously in the second direction are not counted. Thus, a pixel in an image made of regular dots can be discriminated from a pixel in another type of image such as a character image. The discrimination of a dot image can be performed fast and precisely.

Abstract: An image formation apparatus for performing a gradation recording by changing a size of a dot on the basis of an image data inputted to the apparatus. The apparatus divides an image into a plurality of blocks each comprising a predetermined number of pixels and gives a preferential order with respect to a position within each of the plurality of divided blocks. When the preferential order is higher, the size of the corresponding dot is first enlarged on the basis of a density of the image data. This arrangement can prevent generation of a texture and deterioration of the image resolution irrespective of the case that characters or line drawings are mixed with half-tone pictures in the image.

Abstract: A screen system used in the electro-optical reproduction of half-tone pictures in multicolor prints are generated by an algorithm which simulates a continuous tone image. There is disclosed partial screens and screen systems produced by an algorithm for use with a digitized image which provides a means of simulating a continuous tone image containing a range of gray shades from black to white or a color separation. The "Threshold equation" is the key of the invention as it calculates a threshold gray value that is compared to the desired local image value to determine whether that particular point should be "on" or "off". Which points (spots) are "on" and which are "off" is determined by the function that assigns a "threshold" value (the shade at which a pixel changes from "off" to "on") based on a pixels "x" and "y" coordinates.