Browse Prior Art Database

Dynamic Scale Restoration for a Document Scanner

IP.com Disclosure Number: IPCOM000107674D
Original Publication Date: 1992-Mar-01
Included in the Prior Art Database: 2005-Mar-22
Document File: 2 page(s) / 44K

Publishing Venue

IBM

Related People

Shirley, RE: AUTHOR

Abstract

Disclosed is a system for restoring the correct scale to a scanned image before it is stored. (Image Omitted)

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 100% of the total text.

Dynamic Scale Restoration for a Document Scanner

       Disclosed is a system for restoring the correct scale to
a scanned image before it is stored.

                            (Image Omitted)

      In a linear array scanner, a vertical slice (scan line) of the
document is scanned every fixed interval of time T. Normally, the
document is transported at velocity V in order to create an image
with a horizontal scale resolution of R=T/V lines per inch.

      The document may have to slow down, as during a jam when the
transport must be stopped and started up again. When this occurs, the
system decides on a line-by-line basis which scan lines to store and
which to discard.  The result is an image which is restored to the
normal scale resolution R with no distortion.

      The decision process is shown in the figure.  The variable X is
a continuously updated count of the number of scans between pulses
from an emitter wheel attached to the transport.  N is a constant
which is equal to the value of X at nominal speed.  At each scan time
a store decision is made based on the sign of the variable S.  S is
then adjusted by an amount which is also dependent on this outcome.

      References
M. A. Duncan and R. E. Shirley, "Method of Synchronizing Line Rate
with Document Speed in a Linear Array Scanner," IBM Technical
Disclosure Bulletin 27, 7A, 3712-3713 (December 1984); U.S Patent
4,394,693.