Browse Prior Art Database

INPUT IMAGE DEVICE PROVIDING BACKGROUND DETECTION ARRANGEMENT

IP.com Disclosure Number: IPCOM000026238D
Original Publication Date: 1990-Dec-31
Included in the Prior Art Database: 2004-Apr-05
Document File: 4 page(s) / 191K

Publishing Venue

Xerox Disclosure Journal

Abstract

In the reproduction of copies of an original from video image data created, for example, by electronic input scanning from an original document, it is often desirable to provide features dependent on determining the exterior edges of the document. Such features include, for example, automatic magnification, automatic two-up copying, background deletion to avoid storing a document requiring more space than necessary, etc. In the analogous field of light lens copying this has commonly been done by providing a background, against which the document is viewed, that has a tendency to be distinguishable from the image. Thus, for example, backgrounds have been provided with a yellow color, with a black color, with a white color with a whiter than white color, and various other alternatives. All these alternatives work to some extent, but each suffers from the problem that for some documents the background is not well distinguishable from the sheet edge. Thus, black edges of a sheet cannot be distinguished against a black background, canary paper may not be distinguishable against a yellow background, white paper on a white background is questionably detectable, etc.

This text was extracted from a PDF file.
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This is the abbreviated version, containing approximately 49% of the total text.

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XEROX DISCLOSURE JOURNAL

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XEROX DISCLOSURE JOURNAL - Vol15 No 6 NovembedDecember 1990 447

[This page contains 1 picture or other non-text object]

Page 2 of 4

INPUT IMAGE DEVICE PROVIDING BACKGROUND DETECTION ARRANGEMENT(C0nt'd)

In the reproduction of copies of an original from video image data created, for example, by electronic input scanning from an original document, it is often desirable to provide features dependent on determining the exterior edges of the document. Such features include, for example, automatic magnification, automatic two-up copying, background deletion to avoid storing a document requiring more space than necessary, etc. In the analogous field of light lens copying this has commonly been done by providing a background, against which the document is viewed, that has a tendency to be distinguishable from the image. Thus, for example, backgrounds have been provided with a yellow color, with a black color, with a white color with a whiter than white color, and various other alternatives. All these alternatives work to some extent, but each suffers from the problem that for some documents the background is not well distinguishable from the sheet edge. Thus, black edges of a sheet cannot be distinguished against a black background, canary paper may not be distinguishable against a yellow background, white paper on a white background is questionably detectable, etc.

Various methods are known for distinguishing types of images in a document based on the frequency of the image data. Thus, for example, in U.S. Patent No. 4,194,221 to Stoffel, this problem was addressed by applying a discrimination function instructing the image processing system as to the type of image data present and particularly, an auto correlation function to the stream of pixel data, to determine the existence of high frequency half-tone image data. Moreover, in US. Patent No. 4,811,115 to Lin et al, a method and apparatus for applying an auto correlation function for the determination of the presence of half-tone image data is shown. The auto correlation function is calculated for the stream of half-tone image data at selected time delays which are predicted to be indicative of the image frequency characteristics, without prior thresholding. The arithmetic function used in the auto correlation system of U.S. Patent No. 4, 811,115 to Lin is an approximation of the auto correlation function using logical functions and addition, rather than the multiplication function used in U.S. Patent No. 4,194,221 to Stoffel. Peaks in the resulting auto correlated function are detected to d...