Similarity Pyramid: Browsing a Document Database with

 Similarity Pyramid: Browsing a Document Database with ildus Ahmadullin, Jan Allebach HP Laboratories HPL-2012-21 Document database management; document visual similarity; similarity pyramid; Isomap Managing large document databases has become an important task. Sorting documents with respect to their visual similarity and layout features, and visualization of the whole document database is a desirable application. A user may wish to search for documents in a database that are similar to a query in their stylistic features, or he/she may want to browse the whole database. In these tasks clustering similar documents and organizing the document database with respect to the clusters is preferable to presenting documents in a random order. In this paper, we propose organization of single-page documents in a 3-D hierarchical structure called a similarity pyramid. The pyramid is constructed from a stack of document database embeddings on a 2-D surface with the help of a nonlinear dimensionality reduction algorithm called Isomap. The mapping algorithm preserves similarity dis-tances between documents by mapping documents that are close to each other in a feature space to points on low-dimensional surface that are close to each other. Higher levels of the pyramid consist of document image icons that represent a large group of roughly similar documents, whereas lower levels contain document image icons representing small groups of very similar documents. A user can browse the database by moving along a certain level of a pyramid by moving between different levels. External Posting Date: February 6, 2012 [Fulltext] Approved for External Publication Internal Posting Date: February 6, 2012 [Fulltext] Copyright 2012 Hewlett-Packard Development Company, L.P. Similarity Pyramid: Browsing a Document Database with Respect to Visual Similarity Ildus Ahmadullin, Jan Allebach School of Electrical and Computer Engineering, Purdue University, West Lafayette, IN 47907-1285, U.S.A