Eastman-kodak Company

Eatsman Kodak Company

Stacy M Munechika

Chung-Hui Kuo

Hwai-Tzuu Tai

Christopher B Liston

Frederick E Altrieth, Iii

David R Brent

Yee S Ng

James Alan Katerberg

Matthias Hermann Regelsberger

Stephen J Farnand

Jose M Mir

Michael Thomas Dobbertin

Eric Karl Zeise

Thomas Allen Henderson

Dennis R Kamp

Jerry Eugene Livadas

Richard George Allen

Cumar Sreekumar

Shawn Edward O'Hara

Brian B Mix

Lawrence W Fisher

Stephen J Famand

Frederick Edward Iii Altrieth

A print engine includes a printer module for printing image data in a plurality of different print modes, wherein each print mode has an associated line print time. A data interface receives image data and associated metadata for a print job from a pre-processing system, the metadata including print mode metadata. A digital memory stores a plurality of pulse timing functions, each pulse timing function corresponding to one of the line print times associated with the plurality of print modes. A metadata interpreter interprets the metadata and determines the print mode to be used to print the image data. A printer module controller controls the printer module to print the image data using the pulse timing function corresponding to the line print time associated with the print mode, wherein each light source is activated for a pulse count corresponding to a pixel code value of an associated image pixel.

Print engine with print-mode-dependent pulse timing functions

A method is described for calibrating a linear printhead including an array of light sources. A test target is printed by activating the light sources in the printhead in accordance with digital image data for the test target, wherein a current value for each light source is controlled responsive to an initial set of current control parameters. A digital image capture system is used to capture an image of the printed test target, and the captured digital image is analyzed to determine an estimated exposure gain error for each light source. An updated set of current control parameters is then determined which is adapted to compensate for the estimated exposure gain errors.

Adaptive printhead calibration process

A print engine is adapted to print image data from a plurality of pre-processing systems that supply image data at different image resolutions and halftoning states. A data interface receives the image data and associated metadata including an image resolution parameter and a halftone state parameter. A metadata interpreter interprets the metadata and determines image processing operations that are required to prepare the image data for printing using a printer module. A resolution modification processor module processes the image data to modify its resolution if the metadata interpreter determines that the image resolution of the image data does not match the printer resolution. A halftone processor module processes the image data by applying a halftoning operation if the metadata interpreter determines that the image data is not in an appropriate halftoning state.

Print engine with adaptive processing

A method is described for adjusting the focus position of a linear printhead in a digital printing system. A line image is printed including a plurality of variable linewidth lines at different cross-track positions. A digital image capture system is used to capture an image of the printed line image, and a data processing system is used to automatically analyze the captured image to determine linewidth parameters representing linewidths of the plurality of lines. Linewidth progression functions are determined for the lines responsive to the determined linewidths, wherein the linewidth progression functions represent the linewidth parameters as a function of position. The linewidth progression functions are analyzed to determine defocus characteristics of the linear printhead, which are used to adjust the focus position of the linear printhead.

In-situ printhead focus adjustment

A computational halftoning process determines a halftoned image having halftoned pixel values by processing an array of input pixels. For each input pixel, an array of high-resolution printer coordinates is defined at a higher spatial resolution than the printer resolution, and a coordinate transformation is applied to determine a corresponding array of high-resolution dot coordinates. An array of high-resolution halftoned pixel values is then determined responsive to the code value of the input pixel by addressing a halftone dot function using the array of high-resolution dot coordinates. A halftoned pixel value is then determined by averaging the high-resolution halftoned pixel values.

Computing array of high-resolution halftone pixel values by addressing halftone dot function and averaging values to determine value at printer resolution

Compensation is performed for nonuniformity in a printer. The printer has a photoreceptor and a print head with a plurality of different light sources, each light source capable of producing a plurality of different levels of light. A plurality of stored gain control signals for each light source are related to the light output of that light source. Print job data includes screened pixel levels and a halftone screen specification. The stored gain control signals are adjusted based on the halftone screen specification. The screened pixel levels are modified using the adjusted gain control signals to provide engine pixel levels. Those levels are provided to corresponding light sources to expose the photoreceptor in respective pixel areas with light corresponding to the compensated pixel levels.

Printer nonuniformity compensation for halftone screens

A method for high-speed multi-color printing includes at least one high-resolution sensor array (), wherein an output of the high-resolution sensor array is transmitted to a controller (); at least one low-resolution sensor array (); wherein the controller calculates a correction for stitch; wherein the controller, based on the calculated correction, adjusts a timing of image data provided to individual print elements comprising print stations () to aligned an output of the print elements; and wherein the low-resolution sensor array provides full page viewing.

Method for correcting stitching errors in multi-color high-speed printing

A multi-resolution imaging device () for a high-speed multi-color printer includes at least one high-resolution sensor array (), wherein an output of the high-resolution sensor array is transmitted to a controller (); at least one low-resolution sensor array (); wherein the controller calculates a correction for stitch; wherein the controller, based on the calculated correction, adjusts a timing of image data provided to individual print elements comprising print stations () to aligned an output of the print elements; and wherein the low-resolution sensor array provides full page viewing.

High-speed multi-color printing

Electrophotographic (EP) streaking compensation is performed. A tonescale is measured for each column and a per-column gain computed to compensate for variations. An adjustment tonescale is determined and a per-column adjustment-tonescale gain computed to correct for remaining error after the per-column gain is applied. The two corrections are used together to provide improved compensation quality.

Electrophotographic printing with column-dependent tonescale adjustment

A method of detecting and correcting imaging defects in a media printed on a high-speed multi-color printer includes providing a multisensory imaging device (); illuminating the media; sensing images on the media at high resolution with at least one high resolution sensor () as it passes the multisensory imaging device; transmitting an output of the high resolution sensor to a controller (); sensing images on the media at low resolution with at least one low resolution sensor (); calculating a correction for stitch; adjusting a timing of image data provided to image writers to align the inkjets to produce an optimal cross-track line; and providing a full page view from the low resolution sensor.

Multi-resolution segmented image sensor

Correction data is produced for density errors in prints produced using a printer. While printing a test image, the periods of rotation of one or more rotatable imaging members arranged along a receiver feed path in the printer are measured using respective period sensors. The printed test image is measured along a selected measurement direction and a reproduction error signal representing deviation from aim density is determined. For each period sensor, the autocorrelation of the reproduction error signal for the corresponding period is determined. If the determined autocorrelation exceeds a selected threshold, the reproduction error signal is decomposed at the corresponding period to extract the variation from the measured component. The remaining error signal is separated by frequency terms. The variations from the data at measured periods and the remaining error signal are used to produce a correction signal.

Producing correction data for printer

Methods are provided for automatic cross-track density correction for a print engine having a print head that forms lines of picture elements on a receiver based upon lines of pixel values. In one aspect of the method, the print engine is caused to print a first print having a plurality of different areas along a cross-track direction with target densities and data is received from which measured densities for different ones of the plurality of different areas can be determined. A line density adjustment function is based upon a functional relationship between a cross track position of different ones of the areas and a difference between the measured density and the target density at the different ones of the areas. A production print is subsequently printed according to lines of pixel values for the production print modulated by the line density adjustment function.

Automatic cross-track density correction method

One or more printers or printing systems are connected to a scanning device. Each printer includes one or more color modules that are used during a printing operation. A printer prints a target for each color module or color channel. The printed targets are then scanned by the scanning device. The printed targets may be rotated to any angle and then scanned by the scanning device. The scanned raster data is processed by a controller to detect non-uniformities in at least one density image and to generate one or more correction profiles for the printer. When an image is to be printed, one or more controllers receive the image data and use the one or more correction profiles to correct or compensate for the non-uniformities during the exposure process.

Adaptive exposure printing and printing system

Screened hardcopy reproduction apparatus for applying toner to a receiver using a print engine that may not apply toner uniformly, so the toner applied to the receiver has a non-uniformity. A controller receives an input pixel level and a corresponding input pixel location; a tone-reproduction unit calculates an output pixel level from the input pixel level and a corresponding output pixel location from the input pixel location; a compensator calculates a compensated pixel level from the output pixel level and the output pixel location; and a screening unit calculates a screened pixel level and a screened pixel location from the compensated pixel level, the output pixel location, and a selected screening pattern. The print engine applies an amount of the toner corresponding to the screened pixel level and the non-uniformity to the receiver at a toner location corresponding to the screened pixel location to compensate for the non-uniformity.

Screened hardcopy reproduction apparatus with compensation

A method for calibrating a printer including a light-emitting diode (LED) printhead for non-uniformity on an image plane. The LED recording elements are arranged in a plurality of arrays. A plurality of characteristics () associated with each recording element are measured and from the measured characteristics a plurality of parameters () associated with each recording element is determined. Adjustment factors for a plurality of parameters are combined mathematically to determine an adjusted power density () for each recording element on the image plane. Correction factors () are then assigned to each recording element to correct for the adjusted power density (). The correction factors () are stored in a memory () associated with the LED printhead.

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Fairport, NY, United States of America

Stacy M Munechika