A method for adjusting an inking unit of a printing press is known from EP 0 142 470 A1. Actual reflection values for a printed sheet are determined outside of the printing press via a scanning device, such as, for example, via a plate scanner. Reflection setpoint values of other printed sheets from this printed product are measured, using a densitometer, as the printing press is running. The actual reflection values and the reflection setpoint values are compared with one another in a computer. From the results of this comparison, setpoint values for adjusting the inking unit are calculated. The inking is thus controlled.
A method for adjusting an inking unit of a printing press is known from GB 2 071 573 A. Spectral data on a printed product, acquired inside and outside of the printing press, in both cases using a densitometer, are compared. The comparison values are used to readjust the inking unit.
A method for determining color and/or density values for the monitoring and/or control of the printing process in a printing unit is known from WO 2005/108083 A1 for use especially in a sheet-fed offset printing press. Measuring fields of a printed sheet are measured during the printing process photoelectrically, directly in or on the running printing device. From the measured values, which are obtained in this manner, the color and/or density values for the relevant measuring fields are formed. Measured value deviations, caused by the measurement directly in the printing process with respect to a measurement outside of the printing process, are corrected computationally.
A device for inspecting the image and measuring the color of at least one printed product produced in a printing press is known from DE 43 21 177 A1. The device is comprised of at least one imaging device which supplies image data from the printed product, and a computer device. The computer device acquires all image data from the printed product for the purpose of an image inspection, and uses this image data to determine a measured value for a color evaluation of at least one measuring point, such as a pixel, on the printed product.
A device for metering ink in a printing press, especially a sheet-fed offset printing press, is known from DE 30 40 455 A1. The printing press is comprised of one or more printing units, each of which contains an inking unit and a plurality of cylinders. A densitometric measuring device, for use in measuring the color density of color test areas of the printed product, is situated on at least one cylinder, against which the printed product lies with a surface that is partially printed facing outward. A control device, having a predetermined setpoint value, is connected to the densitometric measuring device. A setpoint value for the control device is supplied to an adjustment element of the inking unit or inking units. Preferably, a final proof is fed through the printing press without a printing run. The color density of the color test areas of the final proof, as measured by the densitometric measuring device, is input into the control device as a setpoint value.
A method for controlling color in a printing press is known from DE 38 12 099 A. Measuring fields on the sheets printed in the printing press are optically scanned. The actual color locus determined for a measuring field via the scanning process is compared with a predetermined setpoint color locus. Ink metering elements of the printing press are controlled so as to decrease the color deviations.
A method of color control and of the zonal presetting of ink metering elements in inking units of rotary printing presses, and especially in inking units of rotary offset printing presses, is known from DE 40 04 056 A1. Printed images, which are produced by the printing press, are scanned, for example via densitometric or colorimetric devices. Values, which are obtained in this manner, can be fed to a computer that determines the ink requirement, using a print substrate scanning logic with a self-learning system or a so-called expert system. During a pre-print run phase, and also during a production run phase, the setpoint values can be continuously updated.
An inline color measuring system for a printing press is known from DE 10 2004 021 601 A1. This system uses a CCD image sensor, for example, to detect spectral, densitometric or color measured values on sheet-type print substrates during production runs. These measured values are used as control parameters for controlling the printing process. The inline color measuring system is calibrated; for example, by feeding measured values, which have been determined offline using a hand-held densitometer, directly to the measuring electronics of the inline color measuring system.