Xerox Corporation

Hung M Pham

Daniel D Truong

Louis D Mailloux

Rosario A Bracco

Farhad D Rostamian

Cathleen J Raker

Sue K Lam

Robert R Thompson, Jr

Cheryl A Pence

George L Harer

Hoan N Nguyen

Robert P Loce

David C Robinson

Michael Branciforte

Joseph W Ward

Thomas Robson

Timothy M Hunter

James O Mitchel

Michael J Thomas

Chi Minh Pham

John L Zanghi

In a method of programming for image enhancement, a content addressable memory is accessed. At least one template is transferred into the content addressable memory. A random access memory is accessed. Enhancement data is transferred into the random access memory. Video data input is inputted into the content addressable memory. Enhancement data is outputted from the random access memory based on the video data matching at least one template.

Method and system for programming for image enhancement

What is disclosed is a novel system and method for minimizing visual artifacts, such as ROS skew and laserbeam bow, in a brick-layer halftone structure. The present method involves determining a line pattern from ROS skew and laserbeam bow profiles which traverses through successive halftone cells displacing pixels along scanlines in the process direction. The amount of displacement is varied as a function of the cross-process location as determined by the line pattern. Pixels along scanlines are shifted in a direction defined by the error profiles. In each halftone cell within which the line pattern traverses, extra pixels (empty pixel spaces created in the halftone cell by the shifting operation) are filled with lost pixels (pixels bumped from the halftone cell during the shifting operation) such that overall density of the halftone cell is maintained. The lost pixels are buffered such that lost pixels are preserved.

Minimizing visual artifacts in a brick-layer halftone structure

In a digital printing apparatus, such as a xerographic or ink-jet printer, test marks, such as halftone patches or fiducial marks for image registration, are generated on demand. Coordinates of a desired location of the test mark within an imageable area (such as on a print sheet or on a photoreceptor), as well as a selection of the desired type of test mark, are entered through a user interface. Also entered is data about conditions under which image-quality tests using the test marks are to be performed. Information about the test mark and test conditions is retained as a small number of scalar values. The system enables test methods for a machine to be changed easily, and a basic set of system software can be readily applied to different types of printing hardware.

Versatile system for creating test images in a digital printing apparatus

A method and apparatus for the control of darkness/lightness in a digital image rendered by a printing system. The technique preferably employs templates to selectively apply different amounts of darkening (lightening) to borders of structures detected within the image dependent upon the need for darkening (lightening).

Method and apparatus for digital image darkness control using quantized fractional pixels

A system for providing an output from a digital printing apparatus which is of higher resolution than the native resolution of the original image data. For a given center pixel area, image data corresponding to pixel areas generally neighboring the center pixel area are attempted to be matched to various templates which are consistent with curved lines in which resolution enhancement of the center pixel would be desirable. In a second stage of template matching, a second set of image data, corresponding to pixel areas further away from the center pixel than the first set of pixel areas, is also attempted to be matched to templates. The second stage of template matching helps to avoid resolution enhancement of image data which is related to a halftone image.

Resolution enhancement for a digital printing apparatus

A lead edge lightening circuit which will lighten a scan line based on a seven by seven pixel area surrounding the current pixel. The area is divided into four sub-areas, each of four by four pixels, and each having the current pixel at one corner. Each sub-area is summed and compared to a threshold number. If the threshold number is equalled or exceeded by at least one of the four sums, an overlay bit, which can be white or black, is output. The current pixel is replaced by a white pixel if a white pixel has been output, otherwise the current pixel remains unchanged.

Quadrant-based density detection for lead edge lightening

An apparatus and method of reducing pixel clock jitter in a raster scanner having a oscillator which generates a pixel clock signal and a start of scan sensor for generating a start of scan signal, includes the generation of an inverted pixel clock signal and an inverted start of scan signal. Based on which of the pixel clock signal or the inverted pixel clock signal has a rising edge closer to the start of scan signal, one of the pixel clock or inverted pixel clock signal is selected to replace the original pixel clock signal. Further selections are prevented from occurring until a subsequent start of scan signal is detected.

Method and apparatus for reducing pixel clock jitter in a laser scanner

Growing community of inventors

San Gabriel, CA, United States of America

Hung M Pham