Adding linguistic constraints to document image decoding: comparing the iterated complete path and stack algorithms

Kris Popat; Daniel H. Greene; Justin K. Romberg; Dan S. Bloomberg

doi:10.1117/12.410844

21 December 2000 Adding linguistic constraints to document image decoding: comparing the iterated complete path and stack algorithms

Kris Popat, Daniel H. Greene, Justin K. Romberg, Dan S. Bloomberg

Author Affiliations +

Proceedings Volume 4307, Document Recognition and Retrieval VIII; (2000) https://doi.org/10.1117/12.410844
Event: Photonics West 2001 - Electronic Imaging, 2001, San Jose, CA, United States

Abstract

Beginning with an observed document image and a model of how the image has been degraded, Document Image Decoding recognizes printed text by attempting to find a most probable path through a hypothesized Markov source. The incorporation of linguistic constraints, which are expressed by a sequential predictive probabilistic language model, can improve recognition accuracy significantly in the case of moderately to severely corrupted documents. Two methods of incorporating linguistic constraints in the best-path search are described, analyzed and compared. The first, called the iterated complete path algorithm, involves iteratively rescoring complete paths using conditional language model probability distributions of increasing order, expanding state only as necessary with each iteration. A property of this approach is that it results in a solution that is exactly optimal with respect to the specified source, degradation, and language models; no approximation is necessary. The second approach considered is the Stack algorithm, which is often used in speech recognition and in the decoding of convolutional codes. Experimental results are presented in which text line images that have been corrupted in a known way are recognized using both the ICP and Stack algorithms. This controlled experimental setting preserves many of the essential features and challenges of real text line decoding, while highlighting the important algorithmic issues.

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Kris Popat, Daniel H. Greene, Justin K. Romberg, and Dan S. Bloomberg "Adding linguistic constraints to document image decoding: comparing the iterated complete path and stack algorithms", Proc. SPIE 4307, Document Recognition and Retrieval VIII, (21 December 2000); https://doi.org/10.1117/12.410844

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