Abstract: Systems and methods are provided for detecting process direction registration errors in a printer. The errors are detected by analyzing a metric of a dash minimum response obtained from a test pattern. The test pattern contains dashes. At least one dash is shifted in the process direction in relation to another dash.

Abstract: A test pattern is written using multiple image beams in a non image zone at set time intervals. The test pattern is sensed and a profile of each beam is determined from the multiple image beams. A minimum reflectance of the profile is determined from the test pattern of each beam thereby providing an exposure of each respective beam. A centroid of a profile is determined from the test pattern of each beam thereby providing a position of each respective beam. At least one of the following is then determined: frequency, amplitude and phase of banding, which is inherent in a printing device, based on the sensed test pattern. A plurality of groups of image beams intensity changes is combined wherein each group is separated by a set displacement. A banding profile is determined from the group beam intensities. At least one banding compensation metric is determined based at least on one of the determined frequency, amplitude and phase of banding.

Abstract: Systems and methods are provided for detecting process direction registration errors in a printer. The errors are detected by analyzing a metric of a dash minimum response obtained from a test pattern. The test pattern contains dashes. At least one dash is shifted in the process direction in relation to another dash.

Abstract: Disclosed is a method and system for calibrating an image capturing sensor. The method and system include generating a test pattern on an image receiving device and measuring one or more colorimetric properties of the test pattern with an image sensor. The disclosed method and system measure the test pattern with the image sensor located in two or more different cross-process positions to determine an independent uniformity profile for the image sensor and the image rendering process.

Abstract: Systems and methods are provided for determining registration errors in the cross process direction of a printer. A first straight line is obtained by detecting line centers of a first plurality of dashes in a test pattern. A second straight line is obtained by detecting a line center positions of a second plurality of dashes in the test pattern. A difference between the off-set of the first straight line and the off-set of the second straight line is used in determining registration errors.

Abstract: A method and system compensates for streak defects in an image formed using a raster output scanning device. A reflectance profile is generated from an image generated by the raster output scanning device. Thereafter, a difference profile is determined. The difference profile is determined based upon the generated reflectance profile and a uniform profile. A compensation profile is generated based on the determined difference profile. The compensation profile represents a change in an intensity profile for the raster output scanning device.

Abstract: Disclosed is a method and system for calibrating an image capturing sensor. The method and system include generating a test pattern on an image receiving device and measuring one or more colorimetric properties of the test pattern with an image sensor. The disclosed method and system measure the test pattern with the image sensor located in two or more different cross-process positions to determine an independent uniformity profile for the image sensor and the image rendering process.

Abstract: Disclosed is a method and system for compensating for printer cross-process nonuniformity. The method and system provide a means to offset a cross-process uniformity profile associated with an image output device, such as a printer, where process direction noise is measured and the cross-process uniformity profile is adjusted accordingly to provide a better representation of the image output device cross-process uniformity profile.

Abstract: A method for measuring spatial uniformity in an image is provided and includes printing a test pattern from an image forming device having a plurality of strips and rows of fiducials proximal thereto. The method further provides for correcting of distortions in an image caused by printing and scanning artifacts and mapping from scanner coordinates to digital image coordinates. A gray level of each strip in the plurality of strips is determined as a function of digital image cross process coordinate. The method further provides for a profile of each strip to be filtered whereby the artifacts from a halftone screen are eliminated.

Abstract: A printing apparatus has a substantially shiny photoreceptor imaging surface, and a photosensor array disposed to receive specularly-reflected light from the imaging surface. A quantity of toner is placed on the imaging surface, and data is derived based on light reflected from the imaging surface. The reflected light is filtered to a color effectively complementary to the toner color. The system avoids noise caused by diffusely-reflected light from powdered toner.

Abstract: Many xerographic machines have a motor polygon assembly (MPA), which is a rotating polygonal mirror. As the MPA rotates, it reflects a modulated light beam to produce scan lines on a photoreceptor. Inconsistencies in the MPA can cause inconsistencies in the scan lines, and therefore banding in a printed document. Misalignment, improper mounting, improper manufacture, or sources can cause the MPA inconsistencies. The banding is periodic, can be measured and can be compensated for. Although the modulated light beam can be modulated by many sources, further modulation using a compensation source can reduce banding.

Abstract: A system removes a light sensor artifact from a light sensor in a printer that is used to obtain reflectance measurements from test patterns printed on an image substrate.

Abstract: A method for processing input document data uses a drop mass history for ink jets in a print head to adjust other document data processing. The method includes ejecting ink in a plurality of patterns onto an image substrate from a plurality of ink jets, each drop in a pattern corresponding to one drop mass history in a plurality of drop mass histories, identifying a relationship between drop masses for the drops in an ejected pattern and a reflectance parameter for the ejected pattern, measuring a reflectance value for each pattern ejected onto the image substrate, and identifying a drop mass value for each drop mass history in the plurality of drop mass histories, each drop mass value being identified from the measured reflectance value for each pattern and the identified relationships between the drop masses and the reflectance parameter for each pattern.

Abstract: Defects in an image forming system may give rise to scratched fiducials, missing fiducial regions, or other defects in an image that can run parallel to the process direction. The present disclosure provides for a fiducial compensation method and system for detecting defects thereby allowing spatial tone reproduction curves to be calculated and applied to a digital image in order to eliminate printed streaks due to a photoreceptor's non-uniformities.

Abstract: Systems and methods are provided for detecting intermittent, weak or missing jets of a printer. The detection is implemented using a test pattern. Detected failed jets may be confirmed using a verification target. A printhead containing nozzles corresponding to detected failed jets may be wiped or purged.

Abstract: Systems and methods are provided for detecting intermittent, weak or missing jets of a printer. The detection is implemented using a test pattern. Detected failed jets may be confirmed using a verification target. A printhead containing nozzles corresponding to detected failed jets may be wiped or purged.

Abstract: An image processing method to reduce streaking on a printed sheet uses a negative feedback system to reduce streaking. The method scans a printed sheet to produce image data. The method further measures gray-levels of the image data and computes a compensation vector from the measured gray-levels as the difference between a nominal tonal-resproduction-curve and local tonal-reproduction-curves. The compensation vector is applied the image data to be printed. The compensation vector emphasizes ranges of frequencies sensitive of the human eye.

Abstract: A system that extends the operational effectiveness of an image reproduction machine without requiring downtime for service by personnel includes a detection subsystem that monitors components of an image reproduction system for detecting a banding defect in the image reproduction system and an automated compensation subsystem for modifying operation of the image reproduction system to compensate for the detected banding defect so that the image reproduction system continues to generate images at an acceptable quality level. The automated compensation subsystem adjusts components and/or data used by image reproduction system to compensate for the identified banding defect without requiring immediate operator or service personnel intervention. This compensation may successfully attenuate the banding defect so that the image reproduction system continues to produce acceptable images without downtime while awaiting service by personnel.

Abstract: Defects in an image forming system may give rise to visible streaks, or one-dimensional defects in an image that run parallel to the process direction. One known method for compensating for streaks introduces a separate tone reproduction curve for each pixel column in the process direction. A compensation pattern according to this invention has alignment marks before and after a halftone compensation region. The alignment marks provide alignment between the printer pixel grid and a scanning pixel grid. The line width of each alignment mark and the gray level in each pixel column of each gray level portion is measured and analyzed to produce a local tone reproduction curve for each pixel column and associated line width. The line widths of the alignment marks can be remeasured to adjust the local tone reproduction curves to compensate for the streak defect when printing.

Abstract: In a printing system, a method is used for adjusting currents to LEDs in an LED printbar to achieve uniformity of the print. The line test pattern and halftone strips test pattern are printed. The test patterns are scanned. An LED line metric of each LED test pattern line and reflectance uniformity of each halftone test strip are measured. A line uniformity difference profile and a set of halftone strips uniformity difference profiles are concurrently calculated. A current value supplied to each LED associated with the test patterns is adjusted to simultaneously optimize the uniformity in the lines test pattern and the halftone strips test pattern.