Extracting indexing keywords from image structures in engineering drawings

A critical operation in the creation of databases of electronic versions of scanned engineering drawings is the automatic extraction of indexing text information from image structures, called title blocks. This paper addresses the problem of locating title block regions and the subsequent extraction of indexing keywords from such regions. A general technique of 2D pattern localization in unsegmented images, called location hashing, is used to locate title blocks. An engineering drawing indexing system then combines title block localization with text recognition to enable indexing text keyword extraction.