Unisys Corporation

Intergraph Corporation

Robert C Kidd

Robert D Klein

Michael J Higgins-Luthman

Gerald R Smith

Charles Martin Zalinski

Robert Chihsung Yen

George E Reasoner, Jr

Daniel R Edwards

Debora Y Grosse

J Brett Lefebvre

Debora I Grosse

A system for processing a stream of digital bit sets, each related to a different subject in a passing array, and including an arrangement for compressing the bit-sets and sending the results to an utilization stage; plus: a preprocessing stage for distributing each bit set in N parallel bit-compression paths, with all input sent to a common input buffer feeding these paths and each compression path being adapted to execute a prescribed first compression to ascertain 'initial factors', and then a prescribed second compression to use the initial factors, with the second compression values selected according to 'word count' factors derived from results of the first compression, and to thus provide a prescribed time-compressed output to the utilization stage; with both compressions performed according to JPEG standards; and the second compressions performed using prescribed selected QM and Huffman table values, and with a post processor stage to accept the compressed; data as 32-bit output and funnel it down to 16-bit output presented to the utilization stage.

Method and apparatus for digital data compression

In a system for processing and imaging documents to develop a stream of digital, video bit sets, each related to a different document is a passing array, this system including an arrangement for simultaneously compressing a number of said bit-sets for different document images and sending the results to output, this arrangement as comprising:

Document processing

A discrete transform image data compression system in which frequency transform coefficients are modified in accordance with a matrix of quantizer values employs a predefined plurality of quantization matrices to adaptively select, on a document-by-document basis, an approximate memory packet size for each document's compressed image data storage by selecting one of the plurality of quantization matrices in accordance with the packet size estimate obtained for each document image. Additionally, the system employs generation of contrast reduction and gray level stretch remapping curves as a function of global image data characteristics, such as a gray level histogram of the document image data. The remapping curves are utilized to preprocess the image data for more effective data compression.

Document image compression system and method

A method and apparatus for scaling image pixel data by a rational scale factor of L/M utilizes look-up tables for input pixel addressing and convolution of up to two adjacent input pixels which offers an improved implementation of a conventional sampling rate conversion system wherein the input pixels are upsampled by a factor of L by inserting L-1 zeroes, interpolating the zero upsamples by finite impulse response techniques and down-sampling the interpolated data by a factor of M.

Loop-up table image scaling for rational factors

A method of generating a remapping function for use in converting near-photographic document image pixel gray level data lying in a first range of gray level values to higher contrast, background-suppressed pixel gray level data lying in a second more limited gray level range. Global document information, such as a histogram of all the document's original pixels, is used to generate at least one threshold gray level value and to determine the shape of the remapping function on either side of the threshold. Preferably, the remapping function is implemented by a look-up table addressed in accordance with the original pixel data.

Method for adaptively thresholding grayscale image data

An image scaler which enlarges gray scale images, comprised of any number of gray scales, by any rational factor expressible as a ratio of integers between 1:1 and 2:1. The scaling method is 'data conservative' in that it always keeps all of the original gray scale pixel values of the input image, generating additional pixel values as needed to produce an enlarged output image. The scaler generates an insertion number sequence for determining where to insert vacant pixel storage locations and calculates gray scale values for those newly created vacant locations by interpolating between values of neighboring pixels.

Method and apparatus for enlarging gray scale images

A method for reproducing images using rotated screens, wherein the rotated screens are formed by the replication of a screen tile (ABCD). The screen tile (ABCD) is based on a seed screen cell (11, 17) that is disposed at the desired angle of screen rotation, theta, and is replicated so as to fill the screen tile. Thus, the screen can be generated by replicating the screen tile with respect to the same coordinate system as that identifying addresses for the image data being screened, i.e., without rotating the screen tile. Both the screen tile and the seed screen cell (11, 17) are represented by matrices. Noise (51) can be introduced into process of forming the screen in order to further lessen Moire patterns.

Growing community of inventors

Ann Arbor, MI, United States of America

Robert C Kidd