The segmentation of a document image in WISDOM++The segmentation of the document image into rectangular blocks enclosing content portions is performed by means of a variant of the Run Length Smoothing Algorithm (RLSA).
The original algorithm (Wong et al., 1982) applies four operators to the document image:
Horizontal smoothing with a threshold ChVertical smoothing with a threshold CvLogical AND of the two smoothed imagesAdditional horizontal smoothing with another threshold Ca.and, although conceptually simple, requires scanning the image four times.
WISDOM++ implements a variant where:the image is scanned only twice with no additional cost (Shih& Chen, 1996);the smoothing parameters Cv and Ca are adaptively defined on the ground of the spread factor;the segmentation is sped up since it is performed on a document image with a resolution of 75 dpi (reduced document image).
- Shih, F. Y., S.-S. Chen. 1996. Adaptive Document BlockSegmentation and Classification. IEEE Trans. on Systems, Man, and Cybernetics- Part B, 26(5), 797-802.
- Wong, K. Y., R. G. Casey, F. M. Wahl. 1982. DocumentAnalysis System. IBM Journal of Research Development 26(6), 647-656.
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