Multilevel character templates for document image decoding

Gary E. Kopec

doi:10.1117/12.270070

3 April 1997 Multilevel character templates for document image decoding

Gary E. Kopec

Proceedings Volume 3027, Document Recognition IV; (1997) https://doi.org/10.1117/12.270070
Event: Electronic Imaging '97, 1997, San Jose, CA, United States

Abstract

Early work in document image decoding was based on a bilevel imaging model in which an observed image is formed by passing an ideal bilevel image through a memoryless asymmetric bit-flip channel. While this simple model has proven useful in practice, there are many situations in which the bit-flip channel is an inadequate degradation mode. This paper presents a multilevel generalization of the bilevel model in which the pixels of the ideal image are assigned values from a finite set of L discrete 'levels. Level 0 is a background color and the remaining levels are foreground colors. The observed image is bilevel and is modelled as the output of a memoryless L-input symbol, 2- output symbol, 2-output symbol channel. The multilevel model is motivated in part by the intuition that pixel sin a character image are more or less reliably black, depending on their distance from an edge. In addition, the multilevel model supports both 'write-black' and 'write-write' levels, and thus can be used to implement a probabilistic analog of morphological 'hit-miss' filtering. In experiments with the University of Washington UW-II English journal database, the character error rate with multilevel templates was about a factor of four less than the error rate with bilevel templates.

Citation Download Citation

Gary E. Kopec "Multilevel character templates for document image decoding", Proc. SPIE 3027, Document Recognition IV, (3 April 1997); https://doi.org/10.1117/12.270070

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available