Heidelberger Druckmaschinen Ag

Helmut Siegeritz

Nikolaus Pfeiffer

Martin Mayer

Manfred Schneider

Axel Hauck

Günter Bestmann

Stefan Bollmann

Ulf Delang

Bernd Utter

Friedrich Heuss

Sebastian Eggert

A method for reducing the effect of defective printing nozzles in a multicolor printing process on an inkjet printing machine. A computer creates a color transformation table that, for every process color of the inkjet printing machine, includes a replacement combination of the respective other process colors with a minimum color distance to the process color in question. The color transformation table is used to compensate for a defective printing nozzle. The color transformation table is created by printing and measuring a test chart with all process colors and interpolated by the computer. The color transformation table is then optimized to avoid undesired transitions between supporting points of the color transformation table and the resultant color transformation table accordingly contains process color combinations with minimum sensitivity to defective printing nozzles and the optimized table is used to carry out the multicolor printing operation on the inkjet printing machine.

Method of fail-safe color transformation

A method for printing on an inkjet printing machine including color space transformation between target and process color spaces using a computer, includes calibrating the machine by printing and colorimetrically measuring a process color space test chart for printing in the target color space including printing-operation-related limitations in the applied ink amount. The generated measured values correspond to sampling points in the measured target color space. The sampling points are interpolated to define further sampling points. The color space transformation uses sampling points in the target color space and input values from the chart in the process color space corresponding to sampling points in the target color space. The physical variable of ink drop volume is directly used for ink application limitations and input values in the process color space. The calibration of the machine is adapted and the printing operation is carried out.

Method for carrying out a printing operation on an inkjet printing machine

A method for printing on a printing machine with color space transformation using tables formed of n-dimensional orthogonal grids includes printing and colorimetrically measuring a test chart in a target color space providing measured values corresponding to sampling points in the color space, interpolating between the sampling points to determine further sampling points, and using existing sampling points to create an ICC table for color space transformation between target and process color spaces. A computer isolates combinations of n&#x2212;1-dimensional partial grids for process color combinations from grids of the table in the process color space. Partial grids are converted into two-dimensional segments. Sampling points of segments are modified, removing nonrequired sampling points and distributing sampling points in the partial grid. The partial grids are reintegrated into the grid and color management of the printing operation and the printing operation using the reduced ICC table occurs.

Method for optimized color control in a printing machine

A method for transforming device dependent color values [C1, M1, Y1, K1] of a first printing process into device dependent color values [C2, M2, Y2, K2] of a second printing process, the printing processes being characterized by color profiles setting the device dependent color values of the printing processes in a relationship with the device independent color values of the LAB or XYZ color space, includes determining, from the profiles of the printing process, a one-dimensional assignment function K2=f(K1), and describing the paper white of the first printing process by the color values [C2pw, M2pw, Y2pw, K2pw] of the second printing process. Pure gray colors from the first printing process having the device dependent color values [C1=0, M1=0, Y1=0, K1] are transformed into the device dependent color values [C2pw, M2pw, Y2pw, K2pw+f(K1)] of the second printing process. The assignment function is determined from the lightness curves of the first and second color profiles that, in each case, apply to printing only with black printing ink.

Method for the printing-process transformation of the color print for black/white images

A method for correcting digitized image data in the prepress stage when using printing presses having a device-independent color profile in the main printing stage, having the following method steps:

Method for correcting unadjusted printing data on the basis of colormetrically measured reference sheet

A method of determining a printing color profile for printing with N printing inks, which form a color solid of the printable inks in a device-independent color system, includes the steps of selecting one or more printing inks, and defining an inner reference curve in the device-independent color system. The inner reference curve is preferably selected such that it lies in the vicinity of the neutral colors. Using first test forms, which are printed and measured calorimetrically, boundary surfaces between the inner reference curve and the outer envelope of the color solid are defined, which subdivide the color solid into color sectors. With second test forms for the color sectors, a projection of the color sectors in the device-independent color system is determined and, from this, the printing color profile is determined.

Method of determining a color profile for printing with N printing inks

A method is proposed for generating a color profile using the determination of a mapping A&prime; of a device-independent process space Q of dimension m, m being a natural number, to a device-dependent process space K&prime; of dimension n, n being a natural number, for a first set of specific parameters, which is distinguished by the mapping being represented by a concatenation of mappings, which includes a known mapping A from Q to a device-dependent process space K of dimension n, n being a natural number, for another set of specific process parameters, which differs at least in one element from a first set of specific process parameters; and either of a mapping T from K to K&prime; or a self-mapping T by Q .

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Kronshagen, Germany

Helmut Siegeritz