Abstract: A method for image inspection of printed products in a printing material processing machine includes using an image sensor to capture and digitize printed products during image inspection by an image capture system, using a computer to carry out a comparison of captured digital printed images with a digital reference image, examining a result of the comparison for image regions with blurry regions in the captured digital printed image, calculating suitable smoothing factors for the blurry image regions, and then carry out smoothing of the digital reference image with the calculated, suitable smoothing factors for the blurry image regions, causing the digital reference image to have a blurriness comparable to the captured digital printed image in the image regions. Printed products detected as faulty are removed upon an occurrence of deviations of the captured digital printed image from the digital reference image.

Abstract: A method for printing tracks on bodies by using inkjet printing provides printed images with a homogeneous appearance on the bodies, in particular when printing large single-color areas. The homogeneous appearance is obtained by reducing the intensity of the UV radiation from at least one inkjet print head when pinning in track connection regions.

Abstract: A method for detecting defective printing nozzles in an inkjet printing machine includes printing a multi-row printing nozzle test chart formed of horizontal rows of equidistant vertical lines periodically underneath one another, with only printing nozzles in a print head contributing to every row of the test chart corresponding to the horizontal rows. An area coverage element geometrically associated with the test chart is printed, both elements are recorded by an image sensor and analyzed by the computer. The computer analyzes the recorded area coverage element to detect print defects and allocates defects to a region of geometrically close printing nozzles. An analysis of the test chart in the region identifies nozzles causing the defect. Defective printing nozzles are detected based on thresholds, the detected printing nozzles are then compensated, and in the analysis of the recorded area coverage element, influences of the sensor are eliminated by shading correction.

Abstract: A method detects defective print nozzles in an inkjet printing machine by a computer. In a first phase within the context of a print job, print nozzle test patterns are printed beside a subject on a printing substrate. These print nozzle test patterns are then digitized by an image sensor and sent to the computer, where they are analyzed by the computer to determine the current state of the print nozzles, including defective print nozzles. After the first phase, the print nozzle test patterns are modified by the computer on the basis of the current state of the print nozzles and, in a second phase, the modified print nozzle test patterns are printed, digitized and evaluated by the computer with regard to the determination of the current state of the print nozzles and defective print nozzles.

Abstract: A method for modifying color density values in a dot-based printing system uses a control unit. The control unit implements the modification of the color density values after a raster image has been created and modifies the number and/or size of print dots to be applied to a printing substrate in order to attain pre-defined color density target values.

Abstract: A method for detecting and compensating for defective printing nozzles in an ink jet printing machine by using a computer includes printing printing nozzle test charts next to an actual print in a production run, subsequently recording and digitizing the printed printing nozzle test charts by using at least one image sensor, evaluating recorded test charts and, based thereon, defining characteristic values for all printing nozzles contributing to the printed printing nozzle test charts by using the computer, calculating a failure probability for every contributing printing nozzle based on the determined characteristic values by applying a statistical prediction model using the computer, and switching off and compensating for all printing nozzles exceeding a first defined threshold for the calculated failure probability. A printing operation is then carried out on the ink jet printing machine with printing nozzle compensation.

Abstract: A method for detecting printing nozzle errors in an inkjet printing machine provides a high degree of robustness in the detection of errors by printing a nozzle test pattern in the inkjet printing machine. The test pattern is then digitalized by using a camera and transmitted to a computer for evaluation. There, the recorded test pattern is investigated by using methods of digital image processing, such as a Fourier analysis, and evaluated in the frequency range with regard to specific anticipated printing nozzle errors. Specific printing nozzle errors can be detected especially on the basis of amplitude, phase and variance errors in the signal in the frequency range. Moreover, by using the phase error, it is possible to evaluate whether the two print heads are disposed in an incorrect adjustment position relative to one another by calculating displacements of the phase error in transition regions of two print heads.

Abstract: A method for compensating for disruption torques in driving a jetting cylinder in an inkjet printing machine includes recording print image products for at least one color and at least one complete rotation of the jetting cylinder by using an image sensor and using a computer for a time parallel measurement of a driving torque of the jetting cylinder, generating an average gray value profile above a circumferential coordinate based on the recorded image data by using the computer, transforming the average gray value profile and the measured profile of the driving torque into a frequency range by using a computer-assisted Fourier transform and extracting order components from the frequency range. A periodic compensation torque is calculated based on the extracted order components, and the calculated periodic compensation torque is factored-in when actuating the jetting cylinder of the inkjet printing machine in the course of a printing operation.

Abstract: A method for the automated calibration of a printing machine with an image capture system by using a computer, includes putting at least one printed sample substrate with defined deviations into the printing machine, generating a digital image of the printed sample substrate by using the image capture system, calculating current compensation values including defined deviations for configuration parameters of the printing machine relating to optimizing the printing quality by using the computer, and comparing the current compensation values created with target compensation values known from the defined deviations of the printed sample substrate. Serviceability of the printing machine is checked by evaluating the comparison by the computer and/or calibrating the printing machine by using the evaluated comparison by the computer.

Abstract: A method for detecting and compensating defective printing nozzles in an inkjet printing machine includes periodically printing at least one printing nozzle test chart having horizontal rows of equidistant vertical lines underneath one another, with only nozzles contributing to the test chart in every row corresponding to horizontal rows, and printing an area coverage element geometrically associated with the test chart. Both elements are recorded by an image sensor and evaluated by a computer. The computer identifies print defects by evaluating the area coverage element and allocates the defects to defective nozzles. The computer evaluates the test chart based on thresholds to detect defective nozzles and compensate detected defective nozzles. The computer compares the detected defective nozzles from the area coverage element and the test chart to identify detected defective nozzles causing defects in only one element and calculates the thresholds based thereon to minimize the detected defective nozzles.

Abstract: A method corrects color density unevenness during a printing operation on an inkjet printing machine having printing nozzles and a computer. The computer modifies the number or size of the drops to be applied to a printing substrate to attain nominal color density values after the processing of a rasterized print image. For different actual tone values, it is determined which target tone value is required to attain a nominal coloration by measuring a test image for every printing nozzle using a color measurement device, and, based thereon, an area coverage-dependent compensation profile is determined and saved on the computer to be applied in the printing operation to calculate the number and size of the drops on the computer.

Abstract: A method for carrying out a printing operation on an inkjet printing machine compensates for failed printing nozzles by using a computer. After a screening process in which a halftone image is created for an image to be printed, failed printing nozzles are compensated for by increased ink application from neighboring printing nozzles by precalculating at least one corrective halftone image for the adjacent printing nozzles by using the computer, replacing the halftone image created in the screening process by the corrective halftone image in the at least one column of the neighboring printing nozzles, and carrying out the printing operation on the inkjet printing machine using the corrected halftone.

Abstract: A method for compensating for printing substrate deformation in a multicolor duplex printing operation by way of a computer. The substrate deformation that arises when individual color separations are printed onto the first and second sides of the printing substrate in the printing units is established and compensated for in the course of an automated register correction process. The computer calculates a forecast of the substrate deformation on a basis of the established first side deformation parameters of the printing substrate. When further color separations are printed onto the second side the forecast is used as an input parameter for a compensation of the substrate deformation of the second side.

Abstract: Curable compositions are based on ethoxylated triacrylates and alkylglycidyletheracrylates which can be employed to obtain printing products with a soft touch coating. The curable compositions are processed in conventional printing machines where sheets of glossy and matt paper have the curable compositions applied thereto with an anilox roller and then the paper is dried by UV lamps.

Abstract: A method calibrates image sensors and adjusts print heads in an inkjet printing machine via a computer. The method includes printing a test print chart, recording the printed test print chart via an image sensor to create a digital image, determining a coordinate transformation between the coordinates on the test print chart and the coordinates of the image sensor and the print heads, implementing a computer-assisted evaluation process of the digital image to determine the coordinates on the test print chart, deriving correction values for print head adjustment and camera calibration from results of the coordinate transformation and/or the comparison thereof with the determined measured values, and implementing the print head adjustment and the camera calibration by the computer. The test print chart has filled circular discs. The filled circular discs have a minimum diameter that is selected for them to function even if defective printing nozzles occur.

Abstract: A method for printing a print control strip onto a sheet of printing material. The print control strip is divided into strip sections and the strip sections are printed into gripper gaps at the leading sheet edge and/or the trailing sheet edge of the sheet. In a variant embodiment, there is also printed a print control strip onto two sheets of printing material. The print control strip is divided into at least two portions of respective strip sections and the strip sections of a first portion and of a second portion are printed into respective gripper gaps at at least one sheet edge of a first sheet and of a second sheet, respectively. Waste production is eliminated or at least reduced and costs are thus lowered.

Abstract: A method for producing a printed product includes coating a preferably paper or cardboard substrate with a precoat or supplying a substrate that has been coated with a precoat, in which the precoat contains at least one acid, applying a water-based ink to image areas on the coated substrate by using at least one ink print head, and drying the printed substrate and/or the ink, preferably using IR radiation and/or heated air. The precoat includes a photobase generator or a photobase generator is applied at least locally to non-image areas on the substrate, the substrate is irradiated at least locally in non-image areas, preferably using UV radiation, to locally generate a base, and the printed substrate is varnished with a water-based varnish.

Abstract: A method for compensating substrate shrinkage during printing on a printing machine includes generating multiple image parts of a digitally available image to be produced, factoring in information on substrate shrinkage by subdividing the image using a computer, subdividing generated image parts into data blocks using the computer, saving actual positions of blocks in the digital image using the computer, calculating target positions of all blocks in the digital image using the computer by shifting the blocks away from one another by one pixel creating single-pixel-wide gaps between blocks in the digital image, copying and rearranging blocks in the digital image according to calculated target positions using the computer, calculating positions of single-pixel-wide gaps using the computer, filling gaps with digital image data of neighboring pixels using the computer to create a compensated digital image. The compensated digital image is printed on the printing machine.

Abstract: A digital printing machine includes a first sheet-conveying belt made of a first material, a second sheet-conveying belt made of a second material, and a print head for printing on a front side and a back side of the print sheet. The print head is directed towards the first sheet-conveying belt. A reversing device reverses the print sheet between receiving a print on the front side and receiving a print on the back side. A drier dries a print that has been printed onto the print sheet by the print head. The drier is directed towards the second sheet-conveying belt. For instance, the first sheet-conveying belt may be a metal belt and the second sheet-conveying belt may be a plastic belt.

Abstract: A method corrects for defective printing nozzles in an ink jet printing machine via a computer. The defective printing nozzles are compensated for after the screening process by neighboring printing nozzles applying an increased amount of ink. The method includes precalculating different compensation halftones for different area coverages by the computer, printing the compensation halftones embedded in area coverage halftone areas, evaluating the printed compensation halftones via the computer, and selecting and saving, for every area coverage level, the compensation halftone that best matches the coloration of the original halftone in the respective area coverage halftone area. A defective printing nozzle is detected during production printing by the computer. The local area coverage is determined along the detected defective printing nozzle by the computer.