Abstract: Defects in an image 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 ha 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: 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: 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: Diminished intensity defects occur in electrostatic printing between image regions having grey levels, i.e., different electrostatic potential and toner densities. Such defects occur when higher density regions “steal” toner from lower density regions. The system and methods according to this invention compensate for these defects by modifying the input image data. The input image data in lighter regions that precede or occur near a light-to-dark transition to a dark region are raised above the input image values. Thus, when printed, the printed image intensity values in such regions are higher than the corresponding image intensity values. As a result, when the higher density regions steal the extra toner provided due to the raised values, the gray level of the printed image corresponds to the desired gray level. The magnitude of these defects is periodically measured with a calibration pattern to generate and/or update compensation factors used in the compensation process.

Abstract: A method of measuring and controlling high frequency banding, the method includes creating a test pattern, sensing the test pattern with optical sensors, determining a beat frequency based on the sensed test pattern, and determining the frequency, phase and amplitude of high frequency banding based on the beat frequency. An exemplary embodiment of a feedback control method for controlling high frequency banding includes creating a test pattern, sensing the test pattern with optical sensors, measuring high frequency banding and adjusting the imaging parameters based on the measured high frequency banding in order to decrease the extent of high frequency banding. Moreover, an exemplary embodiment of a system for measuring high frequency banding includes an image marking device having a receiving member, optical sensors arranged on the receiving member, and a controller that is functionally coupled to the optical sensors and to the marking device.

Abstract: A method and system for controlling a printing device's tone reproduction curve, which may minimize contouring and help maximize the number of shades or colors available for an output image.

Abstract: Systems and methods provide calibration for a linear array sensor. A test pattern having a plurality of lines is used. Comparison between expected and measured spacing between a pair of neighboring lines is used to determine sensor position displacement.

Abstract: Multiple input patches are received on an output media, which patches are characterized by print density representing a document processing system's response to different input grayscale values over a potential response space. Values associated with the print density of each input grayscale value are measured. Reference Engine Response Curves are determined from the measured print density values and input gray scale values. A variance data representative of a difference between each measured print density value and a respective reference Engine Response Curve is determined. The variance data is transformed into individual components. Based at least on one selected individual component, a set of calibration compensating Tone Reproduction Curves is determined. The determined calibration compensating Tone Reproduction Curves are applied to input grayscale values.

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: Xerographic machines can print documents that have unintentional streaking parallel to the process direction. There are many possible source of the streaking. Currently, the streaking is minimized by using a cross process direction dependent modulation, called a profile, to modulate a modulated light beam being scanned across the photoreceptor. The profile is purely a function of cross process direction position. The profile can minimize, and often eliminate, streaking for any one area coverage, but only for that one area coverage. Different profiles can be produced that work best for different area coverages. Choosing a profile from a group of profiles for use with each scan line can minimize parallel streaking for a wider range of area coverages.

Abstract: System and methods are provided for detecting color separation misalignment in raster optical scanners. A dash minimum response curve is obtained from a plurality of minimal responses sensed from a plurality of dashes in a test pattern. The frequency of the dash minimum response curve a is used to detect skew or bow, depending on whether the frequency is a constant or a variable.

Abstract: Systems and methods provide calibration for a linear array sensor. A test pattern having a plurality of lines is used. Comparison between expected and measured spacing between a pair of neighboring lines is used to determine sensor position displacement.

Abstract: A test target is written in a non image zone at set time intervals. The test target is sensed. At least one of frequency, amplitude and phase of banding, which is inherent in a printing device, is determined based on the sensed test target. At least one banding compensation parameter based at least on one of the determined frequency, amplitude and phase of banding is determined. Characteristics of producing an image based on the determined banding compensation parameter are adjusted to compensate the banding inherent in the printing device.

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.

Abstract: A method and system for monitoring a print drum maintenance system of an image producing machine is disclosed herein in various embodiments. A test pattern is printed on the print drum, and imaged with an image-on-drum detector to determine a printed pattern response. The print drum is then cleaned again imaged with the image-on-drum detector to determine a cleaned print drum response. A cleaning efficiency is computed by comparing the imaged test pattern response to the imaged cleaned print drum response and determining if a failure condition exists by comparing the computed cleaning efficiency to predetermined limits. A corrective process is performed if the failure condition does exist, the corrective process including changing parameters of the drum maintenance system according to the computed cleaning efficiency. The changed parameters are compared to predetermined thresholds and, if not exceeding the thresholds, the cleaning is repeated after the parameters are changed.

Abstract: A method and system for controlling a printing device's tone reproduction curve, which may minimize contouring and help maximize the number of shades or colors available for an output image.

Abstract: Described herein is a printing system having one or more modules for reproducing an image on a substrate; a print media source that supplies the substrate; a finisher that provides finishing capabilities for the substrate; and a controller that uses an unhealthy module with a faulty charger, developer, transferor, cleaner, fuser, etc. to partially process a job.

Abstract: Systems and methods provide calibration for a linear array sensor. A test pattern having a plurality of lines is used. Comparison between expected and measured spacing between a pair of neighboring lines is used to determine sensor position displacement.

Abstract: Defects in an image 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 ha 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: 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.