PDFlib Text Extraction Toolkit (TET) Manual

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pCOS interface for simple access to PDF objects. TET includes pCOS (PDFlib Comprehensive
Object System) for retrieving arbitrary PDF objects. With pCOS you can retrieve
PDF metadata, interactive elements (e.g. bookmark text, contents of form fields), or any
other information from a PDF document with a simple query interface. The syntax of
pCOS query path is described separately in the pCOS Path Reference.
TET Markup Language (TETML). The information retrieved from a PDF document can
be presented in an XML format called TET Markup Language, or TETML for processing
with standard XML tools. TETML contains text, image, and metadata information and
can optionally also contain font- and geometry-related details.
What is text? While TET deals with a large class of PDF documents, not all visible text
can successfully be extracted. The text must be encoded using PDF’s text and encoding
facilities (i.e., it must be based on a font). Although the following flavors of text may be
visible on the page they cannot be extracted with TET:
> Rasterized (pixel image) text, e.g. scanned pages;
> Text which is directly represented by vector elements without any font.
Note that metadata and text in hypertext elements (such as bookmarks, form fields,
notes, or annotations) can be retrieved with the pCOS interface. On the other hand, TET
may extract some text which is not visible on the page. This may happen in the following
situations:
> Text using PDF’s invisible attribute (however, there is an option to exclude this kind
of text from the text retrieval process)
> Text which is obscured or clipped by some other element on the page, e.g. an image.
> PDF layers are ignored; TET will retrieve the text from all layers regardless of their
visibility.
1.2 Many ways to use TET
TET is available as a programming library (component) for various development environments,
and as a command-line tool for batch operations. Both offer similar features,
but are suitable for different deployment tasks. Both the TET library and command-line
tool can create TETML, TET’s XML-based output format.
> The TET programming library can be used for integration into your desktop or server
application. Many different programming languages are supported. Examples for
using the TET library with all supported language bindings are included in the TET
package.
> The TET command-line tool is suited for batch processing PDF documents. It doesn’t
require any programming, but offers command-line options which can be used to
integrate it into complex workflows.
> TETML output is suited for XML-based workflows and developers who are familiar
with the wide range of XML processing tools and languages, e.g. XSLT.
> TET connectors are suited for integrating TET in various common software packages,
e.g. databases and search engines.
1.2 Many ways to use TET 13