Abstract: A method for the digital screening of a halftone image by using a first screen having an arbitrary desired screen width and an arbitrary desired screen angle. For the method, the threshold value matrix of a second screen with a different screen angle and width is read out and compared with the color values of a halftone image presented. In order also to approximate screens having a particular irrational tangent and to avoid unpleasant sudden exposed device pixels in clear regions, it is proposed to provide at least one second threshold value matrix having X3Y3 addresses, the X3Y3 addresses of the second threshold value matrix are displaced by a factor 1/B in relation to the X2Y2 addresses of the first threshold value matrix, and to read out the second threshold value matrix as soon as an error D between the first and the second screen exceeds a predefined limiting value.

Abstract: A method for producing a pseudo-stochastic master surface for producing a cover or jacket of a cylinder for contacting printing material, includes providing the master surface with a pseudo-stochastic distribution of microsurfaces. The master surface is produced on the basis of a digital master in a jacket preliminary stage and serves for a preferably galvanic production of a microstructured cover, in which structure elevations correlate with the microsurfaces. The pseudo-stochastic distribution helps to avoid disruptive discernible effects, for example the moiré effect and helps to construct the microstructuring in a targeted manner. A master surface, a method for producing a cylinder cover, a cylinder cover, a machine for processing printing material, a method for producing printed products and a method for microstamping printed products, are also provided.

Abstract: A register control mark for the detection of positional deviations between at least two color separations printed over one another on a printing material in multicolor printing. The control mark has a pattern with parallel lines of a first color separation and, printed in parallel over the pattern, at least two parallel lines of a second color separation.

Abstract: A method of preparing a print control strip including at least two process control elements and being adapted to at least a width of at least one used area of at least one original image, includes determining borders of the at least one used area. A state is assigned to every process control element in dependence on if the process control element is located substantially inside the borders. A print control strip is created by using only process control elements that have been assigned a state as being inside the borders.

Abstract: A method for digital imaging of a printing form (10) through application of energy is described, in which a burn-off area (66) is detachably fixed by supporting points (68, 84), supporting points (68, 84) being left in place on the printing form (10) through non-imaging of image spots (112) and in which the burn-off from the burn-off area (66) is detached from the printing form (10) in a cleaning step. A supporting point (68, 84) at a reference point is left in place precisely if the number of image spots (110) to be imaged in a surrounding area (18) of the reference point (12) exceeds a limit value and a boundary area (20) in the surrounding area (18) around the reference point (12) contains only image spots (110) to be imaged.

Abstract: A method for producing a pseudo-stochastic master surface for producing a cover or jacket of a cylinder for contacting printing material, includes providing the master surface with a pseudo-stochastic distribution of microsurfaces. The master surface is produced on the basis of a digital master in a jacket preliminary stage and serves for a preferably galvanic production of a microstructured cover, in which structure elevations correlate with the microsurfaces. The pseudo-stochastic distribution helps to avoid disruptive discernible effects, for example the moiré effect and helps to construct the microstructuring in a targeted manner. A master surface, a method for producing a cylinder cover, a cylinder cover, a machine for processing printing material, a method for producing printed products and a method for microstamping printed products, are also provided.

Abstract: A register control mark for the detection of positional deviations between at least two color separations printed over one another on a printing material in multicolor printing. The control mark has a pattern with parallel lines of a first color separation and, printed in parallel over the pattern, at least two parallel lines of a second color separation.

Abstract: A method for the digital screening of a halftone image by using a first screen having an arbitrary desired screen width and an arbitrary desired screen angle. For the method, the threshold value matrix of a second screen with a different screen angle and width is read out and compared with the color values of a halftone image presented. In order also to approximate screens having a particular irrational tangent and to avoid unpleasant sudden exposed device pixels in clear regions, it is proposed to provide at least one second threshold value matrix having X3Y3 addresses, the X3Y3 addresses of the second threshold value matrix are displaced by a factor 1/B in relation to the X2Y2 addresses of the first threshold value matrix, and to read out the second threshold value matrix as soon as an error D between the first and the second screen exceeds a predefined limiting value.

Abstract: A method of preparing a print control strip including at least two process control elements and being adapted to at least a width of at least one used area of at least one original image, includes determining borders of the at least one used area. A state is assigned to every process control element in dependence on if the process control element is located substantially inside the borders. A process control strip is created by using only process control elements that have been assigned a state as being inside the borders.

Abstract: A method for performing a digital multistage screening of a continuous-tone image with a screen having any desired screen resolution and any desired screen angle, in which the screening is carried out by reading out threshold values and comparing the threshold values read out with the color values of the continuous-tone image. Threshold value matrices are used in which the threshold values represent one or more screen dots of a given screen, with which the desired screen resolution and the desired angle are approximated. While the threshold values are being read out, an error between the coordinates of the desired screen and of the given screen is determined, and the error is compensated for by correcting the read address for the threshold value matrix, as soon as the error exceeds a predefined limiting value. Instead of the threshold value matrices, printing-value matrices can also be used.

Abstract: A method for digital imaging of a printing form (10) through application of energy is described, in which a burn-off area (66) is detachably fixed by supporting points (68, 84), supporting points (68, 84) being left in place on the printing form (10) through non-imaging of image spots (112) and in which the burn-off from the burn-off area (66) is detached from the printing form (10) in a cleaning step. A supporting point (68, 84) at a reference point is left in place precisely if the number of image spots (110) to be imaged in a surrounding area (18) of the reference point (12) exceeds a limit value and a boundary area (20) in the surrounding area (18) around the reference point (12) contains only image spots (110) to be imaged.

Abstract: In a method for digital rastering of a half-tone image with rasters having arbitrary screen widths and screen angles, the rastering occurs by reading out a threshold matrix and comparing the thresholds that are read out to the color values of the half-tone image. For that purpose, a threshold matrix is employed wherein the thresholds represent one or more raster dots of a raster arranged at an angle, the desired screen width and the desired angle being approximated therewith. During the readout of the thresholds, an error between the desired raster and the raster approximated by the threshold matrix is calculated, and the error is compensated by a correction of the readout address for the threshold matrix as soon as the error exceeds a predetermined limit value. Alternatively, stored bit patterns can be employed instead of the threshold matrix, these having been acquired by comparing the tonal values to be reproduced to a threshold matrix.

Abstract: A method for performing a digital multistage screening of a half-tone image with a screen having any desired screen resolution and any desired screen angle, in which the screening is carried out by reading out threshold values and comparing the threshold values read out with the color values of the half-tone image. Threshold value matrices are used in which the threshold values represent one or more screen dots of a given screen, with which the desired screen resolution and the desired angle are approximated. While the threshold values are being read out, an error between the coordinates of the desired screen and of the given screen is determined, and the error is compensated for by correcting the read address for the threshold value matrix, as soon as the error exceeds a predefined limiting value. Instead of the threshold value matrices, printing-value matrices can also be used.

Abstract: A method for generation and storage of digitized threshold density values for use in creating a half-tone image pattern such as in the form of color separations. The threshold density values in a sub-cell of a multiple reference cell (supercell) are stored as storage words in accordance with a spot function. A sorted sequence is determined tailored in accordance with the spot function and threshold density values are allocated to the words in accordance with position of the words in a sorted sequence. Corrections are made to the threshold density values in order to compensate for different numbers of storage words in the subcells.

Abstract: The object of the invention is a progress for generating and storing digitized density thresholds for defining the grid of a halftone image. The density thresholds of a section of a grid are stored in a data store as stored words depending on a multiple spot function. In the section, several spots with a number of stored words form a multiple spot and are periodically arranged beside and above one another. A sorted sequence is found for the stored words of the section in accordance with the spot function. Density thresholds are allocated to the stored words depending on the position in the sorted sequence. The actual number of stored words is found individually for each spot in the section. The sorted sequence is generated according to the current spot function. Before position-dependent thresholds are allocated the stored words, a center of concentration and final point correction is performed for the spot concerned.

Abstract: The object of the invention is a process for generating and storing digitized density thresholds for defining the grid of a half-tone image. The density thresholds of a section of a grid are stored in a data store as stored words depending on a spot function. In the grid section, several spots with a number of stored words form a multiple grid spot and are periodically arranged beside and above one another. A sorted sequence is found for the stored words of the section in accordance with the spot function. Density thresholds are allocated to the stored words depending on the position in the sorted sequence. The actual number of stored words is found individually for each spot in the section. The sorted sequence is generated according to the current spot function. Before position-dependent thresholds are allocated to the stored words, a center of concentration and possibly final point correction is performed for the spot concerned.

Abstract: The method optimizes frequency-modulated rasters for recording black-and-white or chromatic raster images. An image to be recorded is optoelectronically scanned and is digitally stored in the form of the individual gray scale values that were allocated to the individual pixels. Threshold decisions are implemented using the gray scale values, a decision being made as to whether or not a pixel is set in the rastered recording of the image.