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Browse Prior Art Database

Dynamic Black White Conversation on Software Image

IP.com Disclosure Number: IPCOM000117532D
Original Publication Date: 1996-Mar-01
Included in the Prior Art Database: 2005-Mar-31
Document File: 2 page(s) / 60K

Publishing Venue

IBM

Related People

Bruegmann, W: AUTHOR [+2]

Abstract

A main goal of a dynamic black and white conversion is to provide high quality bi-level images with stable behavior over time, independent of scanner variations and useable for machine and/or hand printed characters. A measurement for a black and white image quality is the recognition rate of an OCR system. The results received are comparable with results received by much more expensive scanners.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 60% of the total text.

Dynamic Black White Conversation on Software Image

      A main goal of a dynamic black and white conversion is to
provide high quality bi-level images with stable behavior over time,
independent of scanner variations and useable for machine and/or hand
printed characters.  A measurement for a black and white image
quality is the recognition rate of an OCR system.  The results
received are comparable with results received by much more expensive
scanners.

      The scanner transfers the different contrast levels of the
medium to be scanned via a row of photoelectric cells to an analog
voltage output (e.g., an array of Charge Coupled Devices (CCD).  The
voltage output has to be corrected by gain and offset to fit to the
analog to digital converter input specification.  The A/D converter
output gives a specified number of values.  Depending of the quality
of the described circuit there are 1, 4, 8 a.s.o. output bits
possible.

      The appearance of the incoming gray value image of the
scanner in use showed different frequencies from several sources,
e.g., horizontal stripes from uncompensated or bad compensated cells,
deviations of the CCD row itself, misaligned optical equipment as the
rodlens array and different illumination density.  Furthermore,
several gray level changes in vertical direction were found due to
excentric transport rollers.  Lastly, the document medium itself may
be crumbled,  sticky or dirty, which results in undefined gray level
cha...