Abstract: A system and method for detecting alteration of a document. The invention evaluates markings in half-tone fields by ascertaining a first dot count of dots isolated from the marking in the half-tone field of the document; forming an image of the marking; superimposing the image on a blank half-tone field having the same predetermined pattern as the half-tone field of the document; ascertaining a second dot count of dots isolated from the image superimposed on the blank half-tone field; and determining whether the marking has been altered by comparing the first dot count to the second dot count. An alteration is indicated where the first dot count and second clot count are different.

Abstract: A method of producing a printing plate on a cylindrical printing-plate carrier in a rotary printing press uses a digital imagesetting unit and a raster image processor. The method includes subdividing the printing-plate carrier by computation in terms of its width and axial length into at least two circumferential subareas. Then an actual transfer characteristic curve for each subarea is determined and each actual transfer characteristic curve is compared by computation with a predetermined desired printing characteristic curve to find a deviation of the actual transfer characteristic curve from the desired characteristic curve of each subarea.

Abstract: In a method for operating an engraving member in an electronic engraving machine to engrave printing forms, especially printing cylinders for intaglio printing, a stylus of the engraving member is controlled by an engraving signal and engraves a sequence of cups arranged in a gravure screen in the rotating printing cylinder. The engraving signal is formed by superimposing the image signal representing the tone gradations to be engraved. In order to obtain good quality engraving, the engraving member is heated to a temperature that is close to operating temperature before engraving starts and/or during an interruption of engraving. For this purpose, the engraving member is driven with a periodic signal whose frequency is preferably located inside the ultrasonic range in order to avoid noise disturbances.

Abstract: A method, associated software and resulting printing plate having both solid and halftone areas comprising ink cells. Ink cells may be provided in the solid areas according to a first pattern with a first density and size of cells per unit area, and in the halftone areas superposed on selected numbers of halftone dots. The selection of halftone dots with superposed ink cells may be according to a second pattern with a second density and size of cells in the halftone area that is a function of halftone dot size and that may or may not be related to the first pattern.

Abstract: Method for producing a raster surface for use in the coloring of a contact lens, in which method an image surface consisting of picture elements is selected, the image surface is subjected to a tonal reduction operation and a threshold tone value is defined for it, and picture elements darker than the threshold value are made black while picture elements lighter than the threshold value are made white, and the black-and-white image surface is subjected to radial stretching in relation to a given point, the position of said point corresponding to the center of the contact lens to be treated, whereupon a raster pattern for the image to be created on the contact lens can be produced using the image surface, i.e. raster pattern thus obtained.

Abstract: In a method for processing signals in an electronic engraving machine for engraving printing forms, engraving control signals for guiding the stylus of an engraving element are obtained from engraving data representing predetermined tone values between “light” (white) and “dark” (black). The stylus engraves a series of cups in the printing form. The cup depths determine the tone values actually engraved. Before engraving, the engraving control signals corresponding to “light” and “dark” are calibrated by adjustment variables so that the engraved “light” and “dark” tone values correspond to the predetermined “light” and “dark” tone values. So that the “light” engraved tone value remains constant when the “dark” tone value changes, the difference between the old “dark” adjustment variable and a new “dark” adjustment variable is formed before engraving.

Abstract: A computerized method for controlling the density of pixels deposited by a print engine includes the steps of: (a) obtaining a two-dimensional pixel map of an image to be printed; (b) comparing a value of a first pixel element in the pixel map with values of pixel elements adjacent to the first pixel element in the pixel map; (c) changing the value of the first pixel element responsive to a determination, in the comparing step, that a predetermined number of pixel elements adjacent to the first pixel element have the same value as the first pixel element; and (d) dispatching the pixel map to a print engine. The comparing step (b) includes the steps of assigning like-value pixel elements immediately adjacent to the first pixel element a first weight, assigning like-value pixel elements diagonally adjacent to the first pixel element a second weight, different than the first weight, adding the assigned weights together to produce a total weight, and testing the weight against a predetermined threshold.

Abstract: An image recording system is provided with an image data producing apparatus to produce and output halftone dot image data corresponding to a single sheet of output image, for each of plural colors successively; an image recording apparatus having a drum, a rotation driving mechanism, an optical unit to expose the light sensitive material on the drum to plural color light simultaneously in accordance with the halftone dot image data of plural (N≧3) colors, and a sub-scanning mechanism to move the optical unit in a direction parallel to a rotation axis of the drum; and an image data storing apparatus to store the halftone dot image data and to output the halftone dot image data to the image recording apparatus, the image data storing apparatus comprising plural memory devices each storing the halftone dot image data corresponding to a single sheet of the output image for one of plural (N or N−1) colors.

Abstract: In general, in one aspect, the invention features a method for reproducing a contone image as a halftone image on a recording medium, using threshold values in a threshold matrix, including the steps of providing a base supercell suitable for periodically tiling a plane, which has a plurality of microdots and a plurality of virtual halftone dot centers; assigning an ordering sequence consisting of a series of numbers on the virtual halftone dot centers in the base supercell; assigning threshold values to microdots in response to the ordering sequence thereby generating the threshold matrix in the base supercell; and using the threshold matrix in combination with the contone image to generate a screened halftone image on the recording medium.

Abstract: A method of constructing a halftone screen includes selecting a frequency and screen angle of interest. A subcell having spatial vectors which satisfy the selected frequency and screen angle of interest is identified. A supercell comprising an array of the subcells is formed. An integer relationship potentially having numerous solutions exists between the supercell and the subcell. The integer relationship is solved for values of the integers and then tested against the values for the subcell spatial vectors. Although the solution may in some cases be the null set, in many cases there will be numerous solutions. Each resulting solution, if any, is then tested according to any additional constraints or tolerances specified for the particular halftone screen. If any of the resulting supercell solutions satisfies the tests, that supercell may be used to create a halftone screen.

Abstract: A halftoning method utilizes staged, overlapping pixel intensity growth in a halftone cell in rendering a halftone image with multi-level pixels.

Abstract: A computer implemented method to include microscopic perforations (perforations) in an printing plate is revealed. The particles improve the properties of the plate towards printability of an image on different kinds of offset presses. The perforations are formed by perforations which are added in a fully digital way. Aspects of the invention include of three alternative embodiments for include the repelling particles, and these alternative embodiments may be uses alone or in combination depending on the user's preferred workflow. The third alternative embodiment adds the perforations through an additional layer in the page description, this layer comprising a pattern which erases small particles in the original design elements. The first alternative embodiment adds the perforations through a modified screening method. The second alternative embodiment includes perforations into existing bitmaps.

Abstract: An AM half-tone screening process having special utility with a flexographic printing process is described. Such printing processes typically include a desktop publishing unit, a raster image processor for forming half-tone separations, and an image sitter for producing the half-tone separations. In accordance with the invention, the image area is divided into a multiplicity of groups of equally spaced dots. The combined value of the dots in a single group is set at a desired target film value but the individual dots vary in size for film values below a selected transition level. The minimum value of one of the dots can be determined by the operator of the system and, for example, may be greater than the size of the anilox cells in the printing process so that emersion of the raised area into the cell is not possible. The remaining dots of the group decrease in size in proportion to the target film value at a faster rate than the first dot.

Abstract: This invention relates to a system and method for intelligently placing in a periodic and/or random manner a plurality of whetting areas which facilitate lubricating and/or cooling a doctor blade in a printing press when the cylinder is placed therein. The system and method includes one or more routines which analyzes engraving/etching data and any associated white-span length. One or more whetting areas are placed in a periodic or random pattern in response thereto. The whetting areas facilitate lubricating and/or cooling the doctor blade so that it does not heat beyond a predetermined level, thereby avoiding scoring of the cylinder and problems associated with deterioration of print quality or length of cylinder life resulting from thermo-dynamic expansion and/or undesired evaporation of ink associated with areas which make up the image.