Many document-based applications, including popular Web browsers, email viewers, and word processors, have a 'Find on this Page' feature that allows a user to find every occurrence of a given string in the document. If the document text being searched is derived from a noisy process such as optical character recognition (OCR), the effectiveness of typical string matching can be greatly reduced. This paper describes an enhanced string-matching algorithm for degraded text that improves recall, while keeping precision at acceptable levels. The algorithm is more general than most approximate matching algorithms and allows string-to-string edits with arbitrary costs. We develop a method for evaluating our technique and use it to examine the relative effectiveness of each sub-component of the algorithm. Of the components we varied, we find that using confidence information from the recognition process lead to the largest improvements in matching accuracy.
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