Browse Prior Art Database

Window Shifting Skew for Optical Mark Reader

IP.com Disclosure Number: IPCOM000099306D
Original Publication Date: 1990-Jan-01
Included in the Prior Art Database: 2005-Mar-14
Document File: 2 page(s) / 59K

Publishing Venue

IBM

Related People

Itoh, M: AUTHOR

Abstract

A program is disclosed for an OMR (Optical Mark that reads facsimile images of the mark sheet form recognizes whether each mark area is marked or not. A point of the algorithm described is that is needs only one-line work buffer to store the facsimile image.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 77% of the total text.

Window Shifting Skew for Optical Mark Reader

       A program is disclosed for an OMR (Optical Mark that reads
facsimile images of the mark sheet form recognizes whether each mark
area is marked or not.  A point of the algorithm described is that is
needs only one-line work buffer to store the facsimile image.

      The common difficulty of OMR algorithms relates to paper  In
most conventional OMR algorithms, the input image is corrected by
being sheared vertically in the  But this process needs quite a large
buffer and time because it must move the image.  The method described
here uses a "window shifting" for skew compensation.  By this method,
large image and image preprocesses are not required.

      Basically, the OMR process counts dots in every mark  However,
if the OMR sheet skews, every mark area is always in line.  The is
the area in which the mark areas are The window is specified by left
and right Fig. 1 shows the shifting method of window in the right
hand down skew case.

      Until the left timing mark is found, the left and right
boundaries are at the leftmost position.  After the mark is found,
the window right boundary is shifted the right line by line.  The
shift value per line is by the skew value.  The larger the skew value
the smaller the shift value is.  The window right is being shifted to
the right edge or until the top of right timing mark is found.

      On the other hand, after the end of the left timing mark f...