Abstract: Examples of an apparatus and method for use with a printing system are described herein. A correction to be applied to a printing system during print calibration is obtained. A distortion is applied to the correction. A relationship between an expected and measured output of the printing system is determined based on the print performed at least in part on the distorted correction. The printing system is calibrated on the basis of the determined correction.

Abstract: In an example, a method includes printing a set of images by transferring print agent between a roller of a print agent source and an electrophotographic surface in a plurality of transfer operations, wherein the roller is controlled to have a first voltage profile during each of the transfer operations. A variation in optical density which is consistent across the set of printed images may be detected, and a second voltage profile correction may be determined based on the variation in optical density. The method may further comprise printing a subsequent image by transferring print agent between the print agent source roller and the electrophotographic surface in a subsequent transfer operation, wherein the roller is controlled to have the second voltage profile during the subsequent transfer operation.

Abstract: In an example, a method includes printing a set of images by transferring print agent between a roller of a print agent source and an electrophotographic surface in a plurality of transfer operations, wherein the roller is controlled to have a first voltage profile during each of the transfer operations. A variation in optical density which is consistent across the set of printed images may be detected, and a second voltage profile correction may be determined based on the variation in optical density. The method may further comprise printing a subsequent image by transferring print agent between the print agent source roller and the electrophotographic surface in a subsequent transfer operation, wherein the roller is controlled to have the second voltage profile during the subsequent transfer operation.

Abstract: In an example, two images of a printed calibration image are acquired using two measurement devices. The measurement devices are offset along an axis so that the two images correspond to two portions of the printed calibration image overlapping along the axis. The printed calibration image comprises a pattern extending across the printed calibration image in the direction of the axis, the pattern defining a shape so that in each image, a portion of the pattern appears as different from a straight line parallel to the axis. The two images are aligned using the two portions of pattern.

Abstract: In an example, a method includes printing a set of images by transferring print agent between a roller of a print agent source and an electrophotographic surface in a plurality of transfer operations, wherein the roller is controlled to have a first voltage profile during each of the transfer operations. A variation in optical density which is consistent across the set of printed images may be detected, and a second voltage profile correction may be determined based on the variation in optical density. The method may further comprise printing a subsequent image by transferring print agent between the print agent source roller and the electrophotographic surface in a subsequent transfer operation, wherein the roller is controlled to have the second voltage profile during the subsequent transfer operation.

Abstract: In an example, a method of operating a liquid electrophotographic printer is described. The method involves applying limits to a printer control signal. In particular, the printer control signal is digitally processed to reduce signal values to within the obtained limits, wherein neighboring values are modified to maintain the total energy of the printer control signal. The liquid electrophotographic printer is controlled using the processed printer control signal.

Abstract: In an example, two images of a printed calibration image are acquired using two measurement devices. The measurement devices are offset along an axis so that the two images correspond to two portions of the printed calibration image overlapping along the axis. The printed calibration image comprises a pattern extending across the printed calibration image in the direction of the axis, the pattern defining a shape so that in each image, a portion of the pattern appears as different from a straight line parallel to the axis. The two images are aligned using the two portions of pattern.

Abstract: In one embodiment, a processor-readable medium stores code representing instructions that when executed by a processor cause the processor to print a print job, and determine target color data for each sheet of the print job while printing the job. The instructions further cause the processor to continually save the target color data to a server for each sheet of the print job as each sheet is printed.

Abstract: Examples of an apparatus and method for use with a printing system are described herein. A correction to be applied to a printing system during print calibration is obtained. A distortion is applied to the correction. A relationship between an expected and measured output of the printing system is determined based on the print performed at least in part on the distorted correction. The printing system is calibrated on the basis of the determined correction.

Abstract: In one embodiment, a processor-readable medium stores code representing instructions that when executed by a processor cause the processor to print a print job, and determine target color data for each sheet of the print job while printing the job. The instructions further cause the processor to continually save the target color data to a server for each sheet of the print job as each sheet is printed.

Abstract: In one embodiment, a processor-readable medium stores code representing instructions that when executed by a processor cause the processor to print a print job, and determine target color data for each sheet of the print job while printing the job. The instructions further cause the processor to continually save the target color data to a server for each sheet of the print job as each sheet is printed.

Abstract: A method of controlling a print engine, the method comprising: printing a first test image including a number of scans of printing components at a first setting of the array of printing components; printing at least a second test image by a number of scans of the printing components at a modified setting of the array of printing components, the modified setting being different from the first setting, wherein the modified setting provides a modified setting for each one of the printing components which is varied according to the position of the respective printing component in the array; optically scanning the printed test images and determining the distinctiveness of a scan band within the printed test images for each one of the test images; and deriving an optimum setting of the array of printing components from a comparison of the determined distinctiveness.

Abstract: In one embodiment, a processor-readable medium stores code representing instructions that when executed by a processor cause the processor to print a print job, and determine target color data for each sheet of the print job while printing the job. The instructions further cause the processor to continually save the target color data to a server for each sheet of the print job as each sheet is printed.

Abstract: In one embodiment, a processor-readable medium stores code representing instructions that when executed by a processor cause the processor to print a print job, and determine target color data for each sheet of the print job while printing the job. The instructions further cause the processor to continually save the target color data to a server for each sheet of the print job as each sheet is printed.

Abstract: An apparatus and method for use in capturing image data of an output of a printing device during a print run, the method comprising capturing a first portion of image data of a first spread, capturing a second portion of image data of a second spread, wherein the location of the second portion of image data on the second spread is different from the location of the first portion of image data on the first spread, and combining the first portion with the second portion to generate oversampled image data.

Abstract: Printing by determining target color values based on first color outputs, determining current color values based on current color outputs, and calculating color compensation values to compensate for a difference between the target color values and the current color values.

Abstract: A method of controlling a print engine, the method comprising: printing a first test image including a number of scans of printing components at a first setting of the array of printing components; printing at least a second test image by a number of scans of the printing components at a modified setting of the array of printing components, the modified setting being different from the first setting, wherein the modified setting provides a modified setting for each one of the printing components which is varied according to the position of the respective printing component in the array; optically scanning the printed test images and determining the distinctiveness of a scan band within the printed test images for each one of the test images; and deriving an optimum setting of the array of printing components from a comparison of the determined distinctiveness.

Abstract: Printing by determining target color values based on first color outputs, determining current color values based on current color outputs, and calculating color compensation values to compensate a difference between the target color values and the current color values.

Abstract: An apparatus and method for use in capturing image data of an output of a printing device during a print run, the method comprising capturing a first portion of image data of a first spread, capturing a second portion of image data of a second spread, wherein the location of the second portion of image data on the second spread is different from the location of the first portion of image data on the first spread, and combining the first portion with the second portion to generate oversampled image data.

Abstract: In an example implementation, a method of iterative calibration includes, in a first iteration, measuring first values of a calibration parameter, and determining first corrections for the measured first values. The method includes, in a next iteration, measuring next values of the calibration parameter that incorporate the first corrections. The first corrections are omitted from the next iteration measurements to provide pseudo iteration measurements, and the first iteration measurements are averaged with the pseudo iteration measurements. Second corrections are then determined based on the averaging.