PDFlib Text Extraction Toolkit (TET) Manual

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Geometry. The geometry features may be useful for some applications: > The TET_get_char_info( ) interface is only required if you need the position of text on the page, the respective font name, or other details. If you are not interested in text coordinates calling TET_get_text( ) will be sufficient. > If you have advance information about the layout of pages you can use the includebox and/or excludebox options in TET_open_page( ) to get rid of headers, footers, or similar items which are not part of the main text. Unknown characters. If TET is unable to determine the appropriate Unicode mapping for one or more characters it will represent it with the Unicode replacement character U+FFFD. If your application is not concerned about unmappable characters you can simply discard all occurrences of this character. Applications which require more finegrain results could take the corresponding font into account, and use it to decide on processing of unmappable characters. Use the following document option to replace all unmapped characters with a question mark: unknownchar=? Use the following document option to remove all unmapped characters from the output: fold={{[:Private_Use:] remove} {[U+FFFD] remove} default} Complex layouts. Some classes of documents often use very elaborate page layouts. For example, with magazines and periodicals TET may not be able to properly determine the relationship of columns on the page. In such situations it is possible to enhance the extracted text at the expense of processing time. Suitable options for this purpose are summarized in Section 6.6, »Layout Analysis«, page 88. See Table 10.12, page 174, for more details on relevant options. Legal documents. When dealing with legal documents there is usually zero tolerance for wrong Unicode mappings since they might alter the content or interpretation of a document. In many cases the text position is not required, and the text must be extracted word by word. Recommendations: > Use the granularity=word option in TET_open_page( ). > Use the password option with the appropriate document password in TET_open_ document( ) if you must process documents which require a password for opening, or the shrug option if content extraction is not allowed in the permission settings and you are in a legal position to extract text from the document (see »The »shrug« feature for protected documents«, page 60). > For absolute text fidelity: stop processing as soon as the unknown field in the character info structure returned by TET_get_char_info( ) is 1, or if the Unicode replacement character U+FFFD is part of the string returned by TET_get_text( ). In TETML with one of the text modes glyph or wordplus you can identify this situation by the following attribute in the Glyph element: unknown="true" Do not set the unknownchar option to any common character since you may be unable to distinguish it from correctly mapped characters without checking the unknown field. 66 Chapter 5: Configuration
Also to ensure text fidelity you may want to disable text extraction for text which is not visible on the page: ignoreinvisibletext=true Processing documents with PDFlib+PDI. When using PDFlib+PDI to process PDF documents on a per-page basis you can integrate TET for controlling the splitting or merging process. For example, you could split a PDF document based on the contents of a page. If you have control over the creation process you can insert separator pages with suitable processing instructions in the text. The TET Cookbook contains examples for analyzing documents with TET and then processing them with PDFlib+PDI. Legacy PDF documents with missing Unicode values. In some situations PDF documents created by legacy applications must be processed where the PDF may not contain enough information for proper Unicode mapping. Using the default settings TET may be unable to extract some or all of the text contents. Recommendations: > Start by extracting the text with default settings, and analyze the results. Identify the fonts which do not provide enough information for proper Unicode mapping. > Write custom encoding tables and glyph name lists to fix problematic fonts. Use the PDFlib FontReporter plugin for analyzing the fonts and preparing Unicode mapping tables. > Configure the custom mapping tables and extract the text again, using a larger number of documents. If there are still unmappable glyphs or fonts adjust the mapping tables as appropriate. > If you have a large number of documents with unmappable fonts PDFlib GmbH may be able to assist you in creating the required mapping tables. Convert PDF documents to another format. If you want to import the page contents of PDF documents into your application, while retaining as much information as possible you’ll need precise character metrics. Recommendations: > Use TET_get_char_info( ) to retrieve precise character metrics and font names. Even if you use the uv field to retrieve the Unicode values of individual characters, you must also call TET_get_text( ) since it fills the char_info structure. > Use granularity=glyph or word in TET_open_page( ), depending on what is better suited for your application. Working with granularity=glyph may result in conflicts between the visual layout of text and the processed logical text created by TET (e.g. the two characters created by a ligature glyph may not fit into the same space as the ligature). Corporate fonts with custom-encoded logos. In many cases corporate fonts containing custom logos have missing or wrong Unicode mapping information for the logos. If you have a large number of PDF documents containing such fonts it is recommended to create a custom mapping table with proper Unicode values. Start by creating a font report (see »Analyzing PDF documents with the PDFlib Font- Reporter Plugin«, page 108) for a PDF containing the font, and locate mismapped glyphs in the font report. Depending on the font type you can use any of the available configuration tables to provide the missing Unicode mappings. See »Code list resources for all font types«, page 109, for a detailed example of a code list for a logotype font. 5.3 Recommendations for common Scenarios 67
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ABC Text Extraction Toolkit (TET) V
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Contents 0 First Steps with TET 7 0
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8.6 Restrictions and Caveats 121 9
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0.2 Applying the TET License Key Us
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Setting the license key with a TET
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CJK support. TET includes full supp
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The TET Plugin is a free extension
Page 16 and 17: new connector for the TIKA toolkit
Page 18 and 19: Table 2.1 TET command-line options
Page 20 and 21: 2.2 Constructing TET Command Lines
Page 22 and 23: Extract images from file.pdf in a r
Page 24 and 25: 3.2 C Binding TET is written in C w
Page 26 and 27: 3.3 C++ Binding Note For applicatio
Page 28 and 29: 3.4 COM Binding Installing the TET
Page 30 and 31: The following method of the String
Page 32 and 33: 3.7 Objective-C Binding Although th
Page 34 and 35: 3.8 Perl Binding The TET wrapper fo
Page 36 and 37: } catch (TETException $e) { print "
Page 38 and 39: 3.11 REALbasic Binding Installing t
Page 40 and 41: oot :to => "home#demo" > Edit app/c
Page 42 and 43: tion occurs, the job log shows the
Page 44 and 45: Acrobat provides only garbage when
Page 46 and 47: BUILD SUCCESSFUL Total time: 2 seco
Page 48 and 49: 4.3 TET Connector for the Solr Sear
Page 50 and 51: SQL> GRANT EXECUTE ON CTX_DOC TO HR
Page 52 and 53: 4.5 TET PDF IFilter for Microsoft P
Page 54 and 55: 4.6 TET Connector for the Apache TI
Page 56 and 57: 4.7 TET Connector for MediaWiki Med
Page 59 and 60: 5 Configuration 5.1 Extracting Cont
Page 61 and 62: 5.2 Resource Configuration and File
Page 63 and 64: product manually, make sure to use
Page 65: 5.3 Recommendations for common Scen
Page 69 and 70: 6 Text Extraction 6.1 PDF Document
Page 71 and 72: How to display with Acrobat X: Tool
Page 73 and 74: 6.2 Page and Text Geometry Default
Page 75 and 76: width (x, y) beta fontsize baseline
Page 77 and 78: * Query ascender and descender valu
Page 79 and 80: 6.3 Chinese, Japanese, and Korean T
Page 81 and 82: Table 6.1 CJK compatibility decompo
Page 83 and 84: Since the PDF document may map pres
Page 85 and 86: Separator characters are inserted b
Page 87 and 88: this situation and recombines both
Page 89 and 90: Table 6.4 Document styles docstyle=
Page 91 and 92: 7 Advanced Unicode Handling 7.1 Imp
Page 93 and 94: Composite characters and sequences.
Page 95 and 96: 7.2.2 Filters for Granularity Word
Page 97 and 98: 7.3 Unicode Postprocessing TET offe
Page 99 and 100: Default foldings. Except for granul
Page 101 and 102: Compatibility decomposition. Charac
Page 103 and 104: In contrast, the following option l
Page 105 and 106: Table 7.7 Unicode normalization for
Page 107 and 108: 7.5 Unicode Mapping for Glyphs Whil
Page 109 and 110: Fig. 7.2 Sample font reports create
Page 111 and 112: glyphmapping {{fontname=Warnock* to
Page 113 and 114: 8 Image Extraction 8.1 Image Extrac
Page 115 and 116: 8.2 Image Merging and Filtering Ima
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8.3 Placed Images and Image Resourc
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8.5 Geometry of Placed Images Using
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8.6 Restrictions and Caveats Image
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Various elements and attributes in
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c h e n 126 Chapter 9: TET Markup
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tet --tetml wordplus file.pdf With
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Object ’objects[49]/Subtype’ do
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Table 9.3 TETML elements and attrib
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9.4 Transforming TETML with XSLT Ve
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document containing the xml process
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[TheSansBold-Plain/13.98] 1 [TheSan
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10 TET Library API Reference 10.1 O
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List containing one option list wit
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Unicode sets. Unicode sets and can
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10.4 Geometric Types Rectangle. A r
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Table 10.2 Global options for TET_s
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10.6.2 Setup C TET *TET_new(void) C
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C++ int delete_pvf(wstring filename
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10.6.4 Unicode Conversion Function
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10.6.5 Exception Handling C++ wstri
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10.6.6 Logging The logging feature
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10.7 Document Functions C++ int ope
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Table 10.8 Document options for TET
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Table 10.8 Document options for TET
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Table 10.9 Suboptions for the glyph
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10.8 Page Functions C++ int open_pa
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Table 10.10 Page options for TET_op
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Table 10.11 Suboptions for the cont
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Table 10.12 Suboptions for the layo
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10.9 Text and Metrics Retrieval Fun
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Bindings C and C++ language binding
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10.10 Image Retrieval Functions C++
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C++ int write_image_file(int doc, i
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10.11 TET Markup Language (TETML) F
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Java and .NET language bindings: th
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estricted pCOS mode if nocopy=false
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10.12 pCOS Functions 191
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Image Retrieval Functions Function
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Index A annotations 71 API referenc
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TET command-line tool 17 TET connec
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