Xerox Corporation

David Jordan Lieberman

Stuart Alan Schweid

Robert P Loce

Beilei Xu

Xing Li

Francis Kapo Tse

John C Handley

Roger Lee Triplett

Aron Nacman

Anthony Paul Lanza

André M Blaakman

Reiner Eschbach

Jon S McElvain

Michael C Mongeon

Charles Michael Hains

John Allott Moore

Mark A Gwaltney

William A Blitz

Connie F Purdum

Adam E Stein

A method adapts image data using more than eight bits per pixel to be compatible with devices using only 8-bit per pixel data. The method separates the higher bit depth data into an 8-bit image data stream, the balance of the bits are carried in a separate tag data stream. The 8-bit image data stream can be used in legacy devices that can handle only 8-bit data, and the tag data stream can be used in legacy devices that incorporate a tag data stream for their internal image processing.

Method for achieving higher bit depth in tagged image paths

A method for encoding and screening electronic integral images in a printing system includes receiving an electronic integral image having a plurality of sub-images comprised of image data, wherein at least one sub-image is spaced apart from another sub-image by a background area; adding temporary image data to at least a portion of the background area image data based on image data of one or more surrounding sub-images so as to reduce the spatial variance across at least a portion of the electronic integral image and to make it more compatible to data compression without significant signal or data loss; and subsequently removing the temporary image data added to the electronic integral image so as to reconstruct an accurate representation of the electronic integral image. A system for encoding and screening electronic integral images is also disclosed.

Encoding and screening electronic integral images in printing systems

An image forming device may select from among a plurality of rendering parameters to include selectable halftone frequency candidates automatically based on an internal determination regarding an operating condition of the device to improve image quality for formed images. As a time varying function of the status and/or condition of the components and/or consumables employed in the image forming device, a capability is provided for the device to independently determine an optimal individual or set of rendering parameters to be employed based on a monitored device status. Available monitoring data for a current overall condition of the image forming device, to include monitoring a condition of the components and/or the consumables within the device, is used to allow the device to internally perform automatic adjustment of one or more image rendering parameters, including automatically implementing an optimal halftone frequency election scheme.

Systems and methods for improving image quality in image forming devices

4+ color management sequentially processes four colors at a time from among the 4+ colors to leverage solution capability using a 4-color management tools. In methods and apparatus for processing 4+ colors, received information of 4+ colors may be processed in a first stage using four colors of the 4+ colors, such as CMYO. The processed four colors are then mapped into three virtual colors. The mapped three virtual colors and one additional unprocessed color of the 4+ colors are then processed in a second stage using a 4-color tool. From this, a second color model of at least five colors (4+) is generated. The resulting four colors determine five printer colors, and are then mapped into three virtual colors. The mapped three virtual colors and one additional unprocessed color of the 4+ colors are then processed in a third stage using a 4-color tool. From this, a third color model of at least five colors (4+) is generated. This modeling and mapping to virtual input can be repeated for once for each color beyond 4 that is supported by the printer. The processed 4+ colors are output to a device, such as a printing engine, for rendering the image.

4+ color management for gamut extension using a virtual CMYK methodology

A color management method, system and storage medium output 4+ color separation signals to a 4+ (5 or more) color print engine. An input source color is converted into virtual intermediate CMYK separation signals using a 4-color management tool, which may be a conventional tool. These virtual intermediate CMYK separation signals are received as input within a digital front end (DFE), which transforms the intermediate signals into 4+ separation signals, such as for a 6-color print engine. A transformation unit of the DFE passes some of the input separation signals through directly as output (without transformation) while transforming others by splitting them into light and dark separation signals, such as light and dark cyan or magenta using a blend curve that will output the same tonal quality. The transformation unit may use a blending curve that takes into account ink-limit constraints and may maximize light colorant usage to improve image smoothness in light image regions.

4+ color management using a virtual CMYK color paradigm

A xerogrpahic system and method use a tri-level development process in which at least one xerographic imaging unit includes a photoreceptor and a pair of developer units. A first developer unit includes a conventional first toner of a given color (CYMK) and a second developer unit includes a hypochromatic light form of the first toner. By use of a specific tri-level process, excellent color-to-color registration can be achieved for each processed color separation because overlap between colorants can be prevented. Moreover, by use of two forms of the same colorant, a smoother tone reproduction curve can be achieved when an aggressive blending strategy is used. Gamut loss and ink limit violation can be avoided by adjusting the blending curve in certain situations. An exemplary implementation uses a four drum, eight color tandem architecture with formulations of Cyan, Magenta, Yellow and Black, as well as corresponding hypochromatic light colorants of light Cyan, light Magenta, light Yellow, and light Black (gray).

Tri-level xerography for hypochromatic colorants

A method and system detects a halftone frequency. A digitized image is received. An autocorrelation function is performed upon the digitized image to generate an autocorrelation function value for each halftone frequency of a predetermined set of possible halftone frequencies. A demerit term for each possible halftone frequency, based upon the autocorrelation function value, is calculated. A halftone frequency from a predetermined set of possible halftone frequencies, based upon the calculated demerit terms, is selected.

Method and system for detection of binary halftone frequencies

The present invention is a method and apparatus for processing image data to accomplish tuning or adjustment of images, so as to modify at least the darkness thereof, using compact, efficient methods and designs.

Darkness control using pattern matching

A first series of control patches is printed with a first marking engine. A second series of control patches is printed with a second marking engine. Relative reflectance values of the patches printed with the first and second marking engines are measured with respective first and second engine response sensors. Based at least on a difference in the measured relative reflectance values of the control patches printed with the first and second marking engines, a relative engine to engine error is determined. The engine to engine error is decomposed into components. Based on the decomposition, adjustment of at least binary values of a digital image is determined so that print density of a first marking engine output substantially matches print density of a second marking engine output.

Automatic image quality control of marking processes

Disclosed herein is an image processing method for producing enhanced halftone edges, particularly suited to those edges which only lie upon the background as apposed to those edges which abut other halftone screens. It utilizes a step of defining border pixels and a step of halftoning those border pixels in a different manner than the halftoning applied to the interior region of the tint or image segment. The preferred halftone for the border pixels will be related to the interior halftone by some number of common spatial frequency harmonics. Examples of common-harmonic screening for an edge include, but are not limited to: (a) same screen with different tone reproduction characteristics (boosted edge values); (b) same screen angles and frequencies with a different spot function, possibly phase shifted; (c) a dot screen whose frequency vectors can be generated by the frequency vectors of the interior screen; (d) a line screen whose frequency vectors can be generated by the frequency vectors of the interior screen. This generation process is directed to ensuring that the two screens will be 'harmonically matched' where at least one of the fundamental frequency vectors and harmonics of the first screen will equal at least one of the fundamental frequency vectors and harmonics of the second screen.

Tinted edge enhancement using harmonic halftones for the boundary pixels

In an image processing method, a first raster having a first resolution is divided into a plurality of sub-sampling cells each containing a selected number of neighboring pixels. A pixel from each of the sub-sampling cells is selected in a periodic or quasi-periodic pattern biased toward selecting a pixel position within each sub-sampling cell that is distal from a selection position within at least one neighboring sub sampling cell. The selected pixels define a second raster having a second resolution lower than the first resolution.

Simulated high resolution using binary sub-sampling

One aspect of the invention provides a method of halftoning an image which involves determining a quantization error for a selected target pixel of an image, selecting a diffusion mask, the mask relating to the target pixel and pixels neighboring thereto, receiving a first pair of neighboring pixel values for a first pixel pair including a first neighboring pixel and a second neighboring pixel, and receiving a second pair of neighboring pixel values for a second pixel pair including a third neighboring pixel and a fourth neighboring pixel. The method further involves determining a ranking order of the first, second, third and fourth neighboring pixels by comparing pixel values of the first, second, third and fourth neighboring pixels, and diffusing error to at least one of the first, second, third and fourth neighboring pixels based on the determined ranking order of the first, second, third and fourth neighboring pixels.

Systems and methods for rank-order error diffusion image processing

A method of adjusting a TRC of an image is provided. The method involves receiving an image at an input resolution, resampling the image to a processing resolution if the imput resolution and the processing resolution are not same, processing the image using rank-ordered error diffusion, and resampling the processed image to a desired output resolution for the image if the processing resolution and the output resolution are not same.

Systems and methods for controlling a tone reproduction curve using error diffusion

A method and system for converting, transforming or translating an imaging element associated with a first resolution into a second imaging element associated with a second resolution are provided. The method and system provide for the selection of output imaging element pattern based on context information extracted from areas neighboring an area undergoing conversion when information extracted from the area undergoing conversion provides an insufficient basis from which to select an output imaging element pattern. Exemplary embodiments are directed toward preservation of area coverage and centroid placement. The method provides for consideration of characteristics of a marking engine in the output imagine element pattern selections process. In xerographic environments clustering can be maximized, thereby reducing xerographic stress. In inkjet environments output pattern selections can be directed toward decreased clustering.

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Fairport, NY, United States of America

David Jordan Lieberman