Segmentation of heterogeneous document images : an ... - Tel

tel-00912566, version 1 - 2 Dec 2013
Figure 1.1: A sample of a correctly segmented document image by ABBYY
FineReader 2011.
improve the segmentation quality for the corpus provided to us, which mostly
consists of handwritten documents with degraded quality and side notes, forms
and books. We start with an introduction to document page segmentation.
1.2 Document page segmentation
Document page segmentation is the main component of geometric layout analysis.
Given an image of a document, the goal of page segmentation is to decompose
the image into smaller homogeneous regions (zones or segments) of
handwritten and printed text. The difference between page segmentation and
layout analysis is that layout analysis algorithms use these segments to assign
contextual labels (title, author, footnote,...) to them and to also find the reading
order of each segment. Figure 1.1 shows a correctly segmented document image.
In multi-columns documents, a page segmentation algorithm is also responsible
for segmenting text columns separately, so that text lines from different columns
are not merged.
The reason for segmenting documents into smaller regions in the first place
is that text regions are sent to an OCR (Optical character recognition) or reading
order detection modules for further processing and to convert them into
ASCII format. Hence, obtained regions should also be classified as containing
text or non-text elements, because character recognition modules assume that
the incoming data contains text, so their outputs are unpredictable for regions
containing graphics or other non-textual components.
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