Image analysis – Image compression or coding
Reexamination Certificate
1994-01-27
2001-03-20
Chang, Jon (Department: 2723)
Image analysis
Image compression or coding
C382S304000
Reexamination Certificate
active
06205248
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
1. (Ser. No. 07/772,893filed Oct. 3, 1991, abandoned, in favor of Continuation application Ser. No. 08/192,937) for a Method And Modular System For High Speed Processing Of Item Images by Wayne M. Doran et al.
2. (Ser. No. 07/770,793) for a Method For Splitting And Configuring A Multi-Channel Image Processing System by Charles K. Pope filed Oct. 3, 1991, now U.S. Pat. No. 5,390,262.
3. (Ser. No. 07/770,792, now abandoned) for a Method And Apparatus For Thresholding And Configuring A Multi-Channel Image Processing System by Charles K. Pope filed Oct. 3, 1991.
BACKGROUND OF THE INVENTION
This invention relates to a method and system for processing image data from an item, like a document, for example, and also for producing a compressed, binarized version of the image data for transmission to or use by subsequent users. In particular, it relates to a method and system for compressing data in a multi-channel image processing system.
In some financial systems, for example, documents, like checks and deposit slips, are scanned by an imager as the documents are moved along a document track by a document transport means. In general, the imager scans along a single scanning line as the document is moved past the imager. With this system, there may be 640 “pixels” or picture elements, for example, in a single scan, depending upon the size and resolution requirements of the system.
A pixel represents image data coming from a portion of the document at the scanning line. The pixel coming from the scanning line is generally an analog signal; however, it is converted, typically, to an eight bit byte of data by an analog/digital converter for further processing by the system. Successive scans of data are obtained as the document is moved past the imager.
The pixel data coming from imaging a document, as described, may be used, for example, to generate an image of the document on a video display or CRT. When so displayed, an operator viewing the image may perform data completion, for example, by entering the monetary amount, etc. (associated with the document) on a keyboard which is part of the financial system.
In recent years, efforts have been made to increase the throughput of documents by reducing the time required to process the image data.
SUMMARY OF THE INVENTION
The present invention is similarly related to reducing the time required to process image data. While the discussion of the invention may proceed with regard to a financial system for ease of explanation, it is apparent that this invention may be used, generally, where image data is to be processed, as, for example, in facsimile transmission.
One of the features of the present invention is that it provides an architecture which facilitates parallel processing of image data or pixels received from a scanning line. The parallel processing is effected by dividing the pixels at a scanning line into a plurality of processing channels.
The architecture mentioned supports direct migration from low to high speed applications by simply adding more processing channels in parallel.
Varying pixel densities at the scanning line, and varying item sizes to be scanned can be accommodated by adding more processing channels or by adding more memory space to a single processing channel.
Currently available imaging devices have one, two, four, and eight output channels, for example. The architecture of the present invention enables the number of output channels from the particular imaging device selected to be used in the system to be independent of the number of parallel processing channels used in the system. In other words, an imaging device having two output channels may be used in a system employing four processing channels.
The architecture of the present system permits the pixel data derived from a scanning line to be processed without intermediate storage, and it also permits identical processors to be used in the processing channels.
Another feature of this invention is that it is able to receive an input of 80,000,000 pixels per second, process them, and deliver them in a format which conforms to the CCITT compression algorithm. The input stated is a function of current technology, and it could be higher in the future.
While this invention is discussed in relation to compression of binarized data, the concepts discussed herein could also be applied to gray scale compression.
This invention relates to a method and system for compressing data in a multi-channel image processing system.
In a first aspect of this invention, there is provided a method of compressing data comprising the steps:
(a) receiving successive columns of binary pixels representing data on a document;
(b) using an examining window to extend over a predetermined number of said successive columns along a direction which is perpendicular to the direction of said columns so as to present a row of pixels;
(c) generating a change of color bit for each of the pixels in the examining window;
(d) examining a pixel under consideration in said window with regard to a reference row and designating coding according to a predetermined code like CCITT; and
(e) repeating steps (b), (c), and (d) for the remaining columns of binary pixels on the document.
In another aspect of the invention, there is provided a method of packing compressed data into a packed word having a predetermined number of bits therein so as to maximize addressing and storing of said compressed data, said compressed data being received in a serial manner and in code words having lengths of a varying number of bits, said method comprising the steps:
(a) receiving a said code word to be packed;
(b) determining a number of valid bits in the code word being examined, with the number of valid bits equalling the number of bits in the associated code word;
(c) storing the code word from step (a) and the associated number of valid bits from step (b) in a memory when the number of valid bits is less than said predetermined number so as accumulate a partially packed code word along with an associated cumulative number of valid bits which is less than said predetermined number;
(d) repeating steps (a), (b), and (c) as needed until the associated cumulative number of valid bits from step (c) when added to the number of valid bits from step (b) is at least equal to said predetermined number, with that number of valid bits needed to equal said predetermined number in step (d) referred to as needed valid bits, and any number of valid bits above said needed valid bits referred to as excess valid bits;
(e) combining the partially packed code word from memory with that portion of the code word associated with the needed valid bits from step (d) to accumulate a said packed word;
(f) outputting said packed word from step (e); and
(g) storing any said excess valid bits and their associated code word bits in said memory.
In yet another aspect of this invention, there is provided a system for compressing data comprising:
means for receiving successive columns of binary pixels representing data on a document;
examining means including an examining window to extend over a predetermined number of said successive columns along a direction which is perpendicular to the direction of said columns so as to present a row of pixels; and
means for generating a change of color bit for each of the pixels in the examining window;
said examining means being effective to examine a pixel under consideration in said window with regard to a reference row and to designate coding according to a predetermined code like CCITT.
The above advantages and others will be more readily understood in connection with the following description, claims, and drawing.
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patent: 4326258 (1982-04-01), de la Guardia
patent: 4398221 (1983-08-01), Yamaguchi
patent: 4410916 (1983-10-01), Pratt et al.
patent: 4433346 (1984-02-01), Stoffel et al.
patent: 4484349 (1984-11-01), McCubbrey
patent: 4509194 (1985-04-01), Harrington
patent: 4571634
Chang Jon
NCR Corporation
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