Image analysis – Image compression or coding – Lossless compression
Reexamination Certificate
1994-02-07
2001-04-03
Chang, Jon (Department: 2623)
Image analysis
Image compression or coding
Lossless compression
C382S271000, C382S304000, C358S296000
Reexamination Certificate
active
06212303
ABSTRACT:
CROSS-REFERENCES TO RELATED APPLICATIONS
1. NCR Docket No. 4111 Ser. No. 07/770,794 Filed Oct. 3, 1991 and abandoned in favor of Continuation Application, Ser. No. 08/188,365 Filed Jan. 27, 1994) for a Method And System For Compressing Data In A Multi-Channel Image Processing System by John O. G. Vieth.
2. NCR Docket No. 4217 Ser. No. 07/770,793 Filed Oct. 3, 1991). for a Method For Splitting And Configuring A Multi-Channel Image Processing System by Charles K. Pope. 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 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.
In a first aspect of this invention, there is provided a method of processing image data derived from scanning a document, with the image data presented in the form of successive scan lines of pixels, said method comprising the steps of:
(a) splitting each scan line of pixels into a plurality of processing channels, with a predetermined number of pixels being located within each of said processing channels; and
(b) initiating processing of the pixels in said processing channels in parallel after a predetermined number of successive scan lines of pixels has been generated but before the entire document has been scanned.
In another aspect of the invention, there is provided a method of processing image data derived from scanning a document, with the image data presented in the form of successive scan lines of pixels, said method comprising the steps of:
(a) splitting each scan line of pixels into a plurality of processing channels having boundaries therefor, with a predetermined number of pixels being located within each of said processing channels;
(b) assigning predetermined pixels located outside a selected one of said processing channels as overlap pixels; and
(c) using said overlap pixels to facilitate processing of the pixels located in the selected one of said processing channels.
In another aspect of the invention, there is provided a method of processing image data derived from scanning a document so as to produce successive scan lines of pixels including a first and a last of said scan lines of pixels, with said scan lines being parallel to a first direction, said method comprising the steps of:
(a) processing said pixels within a said scan line to generate a digital gray scale value for each of the pixels within the scan line;
(b) thresholding each of said pixels within said scan line to generate thresholded pixels;
(c) compressing the thresholded pixels in a second direction which is perpendicular to said first direction, with said compressing being initiated after said first of said scan lines of pixels is derived but before the last of said scan lines of pixels is derived.
In yet another aspect of the invention there is provided a system for processing image data which is received as successive scan lines of pixels which are parallel to a first direction, comprising:
accumulation means including an examination window for accumulating a predetermined number of said scan lines of pixels within the evaluation window which includes an oldest and a newest said scan line of pixels; and
means for compressing said predetermined number of said scan lines of pixels along a direction which is perpendicular to said first direction so as to take advantage of a compression algorithm which compresses data along said second direction; and
said means for compressing being effective for compressing the remaining said scan lines of pixels by dropping off at least the oldest scan line of pixels in the evaluation window and picking up at least a next successive scan line of pixels to be included as said newest scan line of pixels in said evaluation window.
In yet another aspect of the invention, there is provided a system for processing image data comprising:
means for scanning an image of a document so as to produce successive scan lines of pixels;
means for dividing a scan line of pixels into a plurality of processing channels so that each channel comprises a portion of the pixels in the scan line, with each processing channel having a predetermined number of overlapping pixels from an adjacent border or an adjacent channel included therein;
means for processing said pixels within each said channel to produce a digital gray scale value for each of the pixels within the channel; and
means for selecting an examining window for use in thresholding said pixels so that the overlapping pixels are used when the examining window is moved close to the beginning of the channel being
Bray John E.
Doran Wayne M.
Pope Charles K.
Vieth John O. G.
Chang Jon
NCR Corporation
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