Lexmark International, Inc.

Steven Frank Weed

Shaun Timothy Love

Stuart Willard Daniel

Brian Edward Cooper

Timothy John Rademacher

Scott Michael Heydinger

Chengwu Cui

Richard Lee Reel

Mohamed Nooman Ahmed

Ronald Todd Sellers

Khageshwar Thakur

Bryan Scott Willett

Tomasz Jan Cholewo

Michael Ray Timperman

Rebecca Beth Silveston-Keith

Gregory John Sherwood

Allan Chiwan Cheung

Bruce Alan Peltzer

Yao Han

Charles Thomas Wolfe

Buford Rodney Goble

Ross William McFarland

Patrick Alan Casey

Mary Ellen Biddle

A method for reducing specular reflection in an image. The method includes capturing a first exposure of a scan surface using a first of a plurality of light sources, capturing a second exposure of a scan surface using a second of a plurality of light sources, determining which pixels captured by the light sources are speckles, and replacing a value of at least one speckle in the image with a different pixel value.

Method and system for reducing speckles in a captured image

An illumination system for a scanner according to one example embodiment includes an array of visible light emitting diodes including a red, a blue and a green light emitting diode and an ultraviolet light emitting device configured to emit light predominantly in the ultraviolet region of the electromagnetic spectrum. During a scan sequence of the red, blue and green light emitting diodes, at least one of the visible light emitting diodes and the ultraviolet light emitting device are positioned to simultaneously illuminate an object being scanned. In one form, during the sequence, the blue light emitting diode and the ultraviolet light emitting device are simultaneously illuminated while in another the red light emitting diode and the ultraviolet light emitting device are simultaneously illuminated.

LED illumination system for a scanner including a UV light emitting device

In an array of pixels, a method for segmenting a selected pixel of the array between at least two layers including identifying an N-by-N window centered upon the selected pixel, evaluating at least one pixel in the N-by-N window to determine whether the selected pixel is a potential text element, identifying an M-by-M window centered upon the selected pixel when the evaluation determines that the selected pixel is a potential text element, wherein the M-by-M window is smaller than the N-by-N window, and determining whether the potential text element includes text by comparing at least two pixels within the M-by-M window.

Document segmentation for mixed raster content representation

The present invention relates to providing a printing device which allows for user authentication. The printing device may communicate with the authentication device using universal serial bus (USB) protocol, wherein the printing device contains a universal serial bus (USB) host. User authentication may encompass the provision of valid identifying information or presenting sufficient funds as a condition prior to performing a print job or granting access to data.

USB host device for printer interface

The input pixels in an image to be halftoned using error diffusion are dithered using a first type of passband dither. A second type of passband dither may also be added to a thresholding matrix used in halftoning. This second type of passband dither may be the same as the first type of passband dither. In such case, the second type of passband dither is a scaled multiple of the first type of passband dither. The halftoning process may be implemented in an application specific integrated circuit.

Apparatus and method for error diffusion with dither

Methods and image forming systems for approximating the value of a function given specified values of input data using a sparse lookup table. Individual samples are quantized and rounded up or down to an adjacent lattice point of the lookup table. Rather than performing multiple lookup table accesses, which are required using conventional linear interpolation, the disclosed data processing techniques require as few as one lookup table access per sample. The quantized samples are obtained by truncating one or more least significant bits, designated as masked bits, such that the most significant, or index bits, remain. For each sample, the value of an individual one of the masked bits is examined by comparing it with a corresponding entry in a mask array to determine whether the index bits are to be incremented prior to being used as an index to the lookup table. The mask array defines a dithering process whereby different masked bits are examined for different samples, resulting in dithered quantized index bits for the samples, that when used to access the lookup table, yield an average result over a neighborhood of samples that approximates the result that could be obtained using linear interpolation.

Dithered quantization using neighborhood mask array to approximate interpolate

Method for shading an optical sensing element of an optical sensor. Reference values are sequentially obtained of the output signal of the sensing element while relatively moving the optical sensor including the sensing element over a shading reference target. An edge detection filter is applied to each of the reference values obtained in step a) in determining if each of the reference values is or is not from an optical defect on the shading calibration strip. An average is calculated of the reference values obtained while excluding each of the reference values determined to be from any optical defect in calculating the average. The output signal of the sensing element is calibrated to the shading reference target using at least the calculated average.

Method for shading an optical sensing element such as in a scanner

An improved shingle mask is provided for use on ink jet printers which use multi-pass printing (shingling) to form bitmap images. The shingle mask is derived from a shingle mask density distribution which exhibits a substantially trapezoidal shape; the shingle mask density distribution is derived from an accumulated shingle mask distribution (also referred to as a &ldquo;banding profile&rdquo;) having an overall shape of a plateau portion and a substantially smooth decreasing portion, which reduces the number of drops to be printed along the outermost edges of the mask on each swath. This shape reduces banding effects by effectively increasing a number of printed-density bands which are decreased in size, while at the same time not increasing the number of printhead passes over a given area on the print media (which otherwise would negatively impact printed throughput).

Shingle masks that reduce banding effect on ink jet printers

A method of converting a first set of input color values, such as RGB color values, into a set of device colorants, such as CMY color values, includes the step of providing a look-up table associating a respective, predetermined set of CMY color values with each of a plurality of selected sets of RGB color values. The first set of RGB color values includes a first red color value, a first green color value and a first blue color value. A first random number is added to the first red color value to obtain a randomized red color value. A second random number is added to the first green color value to obtain a randomized green color value. A third random number is added to the first blue color value to obtain a randomized blue color value. Each of the randomized red color value, the randomized green color value and the randomized blue color value are compiled together to obtain a set of randomized RGB color values. A closest one of the selected sets of RGB color values in the look-up table is determined which is closest to the set of randomized RGB color values. The first set of RGB color values is converted into a set of CMY color values that is associated with the closest one of the selected sets of RGB color values in the look-up table. The random numbers which are added to the original RGB values are derived through a deterministic process based on the low order bits of those values.

Method of converting color values

Methods and apparatus for using isochronous data transfer mode to communicate between a host computer and a printer. Preferably, the printer receives a sufficient volume of data from the host, such as a computer, over an isochronous communications channel, to begin but not complete one print pass (i.e., line scan or page scan). Subsequently, the print pass is initiated causing a print mechanism to move a printing device relative to a substrate without interruption. Thereafter, sufficient data to complete the pass without interruption is received over the isochronous communications channel during the print pass. The high speed transfer rates afforded by isochronous data transfer allow for printing to be initiated before all of the data necessary to complete a print operation without interruption is received. Moreover, the size of a printer buffer used to store the print data before printing may be considerably reduced to store only a portion of the data needed for an entire print pass.

Methods and apparatus for isochronous printing with minimal buffering

Digital halftoning is used to reduce the number of pixel levels used to represent a multiple dot plane image to a smaller number of pixel levels for display on an output device such as an ink-jet printer. Two algorithms commonly used to halftone the dots of a given dot plane are error diffusion and ordered dither. Error diffusion produces patterns of dots that are pleasing to the human visual system but is computationally complex. Ordered dither operates quickly but produces patterns of dots that are visually objectionable. A method is taught in the present invention that employs error diffusion to halftone dot planes that contain relatively dark dots that are visually apparent, and employs ordered dither to halftone dot planes that contain relatively light dots that are not noticeable. The resulting output is pleasing to the human visual system and computed quickly.

Method and apparatus for color halftoning using different halftoning

Apparatus, system and method is provided in which a primary printer prepares print data for use by its resident print engine, or by an alternate printer. The primary printer includes subsystems for receiving original print data from a device, such as a computer or scanner, and for converting the original print data into a data format compatible with the alternate printer.

Growing community of inventors

Lexington, KY, United States of America

Steven Frank Weed