Background referencing

Details Background referencing Background referencing

1987-03-23

1991-06-18

Boudreau, Leo H.

Image analysis

Histogram processing

For setting a threshold

382 51, 358464, 358465, 358466, G06K 938

Patent

active

050254804

ABSTRACT:
Thresholding and background referencing apparatus are disclosed for use with apparatus for scanning documents having images with object and background regions. The background referencing apparatus receives, from the scanning apparatus, a video signal representing the document image and generation a signal having a value representative of an estimate of the background density level of the document being scanned. The apparatus produces a difference signal representative of the difference between the estimated background level signal and the received video signal. The estimated background level signal is stored, and updated in response to (1) the difference signal being of a first sign associated with transition from object to background, and (2) only small difference signals of a second sign associated with transition from background to object, whereby large difference signals of the second sign result in substantially no change in the stored estimated background level signal.

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IBM Technical Disclosure Bulletin vol. 21, #9. Feb. '79, pp. 3461-3467, (D. Bishop et al.) "Character Recognition Approach Involving Histogram Classification".

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