Xerox Corporation

Stromberg-carlson Corporation

Remo J D'Ortenzio

Peter A Crean

William E Nelson

Carolyn P Grow

Robert W Gundlach

Richard F Bergen

Norman W Zeck

James Milo Sweet

Elizabeth Dubiel Wayman

Joseph A Chizuk

A method, system and computer-readable medium for achieving a target compression ratio for binary images with a minimum of image degradation. Portions of the binary image are strategically replicated and used to replace adjacent portions of the image. This process is continued until a compressed version of the image data satisfies a target compression ratio.

System and method for controlling compression ratio and image quality of binary images

This invention relates to a method and apparatus for controlling image quality and compression ratios in image segmentation. More particularly, the invention is directed to an image segmenting system and method that analyzes and classifies pixel blocks of an image to determine the manner in which the image block should be compressed, e.g. with a lossy or a lossless technique. This approach, which assumes no apriori knowledge of the any specific region of the image, results in effective use of the various known compression techniques and provides improved overall compression ratios and image quality.

Method and apparatus for controlling image quality and compression ratios

A method for digital image compression of a raster image is disclosed which uses different compression methods for selected parts of the image and which dynamically adjusts compression and segmentation parameters to control tradeoff of image quality and compression. The image is encoded into a single data stream for efficient handling by disk, memory and I/O systems. This system provides a stable feedback loop that manages to a fine granularity (typically 8&times;8 pixel blocks) the compression of image data so as to be compliant with a plurality of compression constraints; the management of an incremental bias toward more aggressive compression that selectively applies the more aggressive compression methods to blocks that are the most tolerant with respect to visible artifacts; and the adjustable segmentation and compression parameters used to control the image compression.

Method for compressing digital documents with control of image quality subject to multiple compression rate constraints

A low cost, high speed, JPEG Huffman code decoder. The entire gamut of Huffman codes is partitioned into groups, with each group being associated with it's own small look up table to minimize the overall memory requirements. The current Huffman code is stored in a register. For the disclosed embodiment there are N=4 memories with sizes 128, 256, 128 and 256 elements respectively. For the specific typical Huffman code set cited, the partitioning is: The code words in the first group have 7 bits or less and are decoded in the first memory. The next group has from 5 to 7 leading ones, where the first five 1's are masked out and the remaining bits are used to address the second memory. The remaining codes have at least eight leading ones. Here, the first eight ones are masked out and the remaining bits are used to address the last memory. (In this example, one of the memories is not used). Finally, the first eight bits are used in a selector to enable the correct memory so that a single correct output data word is output. The disclosed N=4 embodiment is designed to handle any custom JPEG Huffman code set. This concept can be extended to other memory partitions (a N=6 example is cited) that might provide some desirable memory vs logic switching tradeoffs.

DX JPEG Huffman decoder

An ionographic printer directs a stream of ions from a source to a charge receptor to create an electrostatic latent image thereon. The ion stream passes through a relatively large aperture having associated therewith a pinch electrode for narrowing the ion stream to a preselected width, and displacing electrodes for positioning the narrowed ion stream within the aperture. Varying the biases of the displacing electrodes causes the ion stream to scan across the aperture to deposit multiple spots of charged areas at desired locations on the receptor. The electrodes can be designed to compensate for spot placement skew and anomalies in the cross-sectional shape of the displaced ion stream.

Apparatus for ionographic printing with a focused ion stream

In a digital printer, method and apparatus for formatting printer control signals. According to the invention, characters to be printed are stored in ASCII format in the memory of a microprocessor system. Successive characters are formatted into an on/off bit mapping where a bit signal corresponds to a blank region and a bit signal corresponds to a darkened region. Eight bit slices of the characters are formatted until an entire print width is completed and stored in an 8 bit.times.N buffer where N varies with the desired printer resolution. In the preferred embodiment two buffers are used so that while the contents of one buffer are used to control the printer the second buffer can be bit formatted under microprocessor control.

Printing system

A separable two dimensional Finite Impulse Response (FIR) digital image processing filter with X-dimension filter section having a delay buffer series to which digitized image signals or pixels are first input. The buffer inputs and output are tapped and pixels tapped off are processed by preset multiplier factors and input to an adder where the processed pixels are summed. The summed pixels are fed to a line buffer series of a Y-dimension filter section, tapped off from the filter inputs and output, and processed by further preset multiplier factors. The processed pixels are input to a second adder and summed to provide filtered output pixels. In a second embodiment, the filter is symmetric and has a center point response of unity. In a third embodiment, the filter X and Y dimension filter sections are reversed.

Filter for image pixels

A digital conference circuit provides greater stability in voice transmission by selectively inverting the signal in alternate conference channels, thereby providing cancellation of parasitic echo signals which tend to create oscillations or ringing. Selective gain control is also provided for conferences of different sizes and efficient use of conference lines is ensured by providing for selective combination of conference groups.

Digital conference circuit

A circuit for eliminating possibly false signals such as those due to contact bounce in electromechanical devices from a stream of digital pulses that represent the instantaneous states of selected conditions at successive intervals. The circuit includes a majority logic detector, two stores, one for storing the input signals, and one for storing the output of the majority logic detector, and means for feeding the input signals and the outputs of the two stores to respective inputs of the detector for comparison.

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Rochester, NY, United States of America

Remo J D'Ortenzio