PDFlib Text Extraction Toolkit (TET) Manual

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Small image filtering. TET ignores very small images if may of those is present on the page. Since the image merging process often combines many small images to a larger image, small image removal is performed after image merging. Only images which can not be merged to form a larger image will be candidates for small image removal. In addition, they must satisfy the conditions for size and count which can be specified in the maxarea and maxcount suboptions of the smallimages option of TET_open_page( ) and TET_process_page( ). In order to completely disable small image removal use the following page option: imageanalysis={smallimages={disable}} 86 Chapter 7: Image Extraction
7.4 Restrictions and Caveats Image color fidelity. TET does not degrade image quality when extracting images: > Raster images are never downsampled. > The color space of an image will be retained in the output. TET never applies any CMYK-to-RGB or similar color conversion. > The number of color components will always be unchanged. For example, RGB images will not be changed to grayscale if they contain only gray colors. Image workarounds. In some situations the color appearance of the extracted image may be different from the visual appearance of the PDF page. While the image shape is preserved, the colors may appear different because of the following reasons: > Image masks are be applied. > Colorized grayscale images are extracted without the color, but as grayscale images. > Since DeviceN color is not supported in TIFF, images with the DeviceN colorspace are extracted as grayscale, RGB, or CMYK images for N=1, 3, and 4, respectively. For N>4 CMYK TIFF images with one or more alpha channels are generated. > Images with Separation colorspace are extracted as grayscale images. The spot color used to colorize the image will be lost. > Images with Indexed ICCBased colorspace: the ICC profile will be ignored. Unexpected results when extracting images. In some cases the shape of extracted images may appear different from the PDF page: > Images may appear mirrored horizontally (upside down) or vertically. This is caused by the fact that TET extracts the original pixel data of the image, without respect to any transformation which may have been applied to the image on the PDF page. > Since image masks are ignored, masking effects will not be reflected in the extracted image. Unsupported image types. The following types of PDF images can not be extracted, i.e. TET_write_image_file( ) will return -1 in these cases: > PDF inline images > Images with JBIG2 compression > Images with Indexed Lab colorspace. 7.4 Restrictions and Caveats 87
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PDFlib GmbH München, Germany www.p
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Contents 0 First Steps with TET 7 0
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10.9 Option Handling 151 10.10 pCOS
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0.2 Applying the TET License Key Us
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1 Introduction The PDFlib Text Extr
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may extract some text which is not
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2 TET Command-Line Tool 2.1 Command
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Constructing TET command lines. The
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Extract images and generate TETML i
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3 TET Library Language Bindings Thi
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TET_CATCH(tet) { printf("Error %d i
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3.4 COM Binding Installing the TET
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3.6 .NET Binding The .NET edition o
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3.8 PHP Binding Installing the TET
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3.9 Python Binding Installing the T
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Exception Handling in RPG. TET clie
Page 35 and 36: 4 TET Connectors TET connectors pro
Page 37 and 38: 4.2 TET Connector for the Lucene Se
Page 39 and 40: Indexing metadata fields. The TET c
Page 41 and 42: 4.4 TET Connector for Oracle The TE
Page 43 and 44: these options on the command line.
Page 45 and 46: TET PDF IFilter is freely available
Page 47 and 48: tracts text and metadata from the P
Page 49 and 50: 5 Configuration 5.1 Indexing protec
Page 51 and 52: 5.2 Resource Configuration and File
Page 53 and 54: tet/3.0/resource /tet/3.0/resource/
Page 55 and 56: Geometry. The geometry features may
Page 57 and 58: 6 Text Extraction 6.1 Document Doma
Page 59 and 60: How to search with Acrobat 8/9: not
Page 61 and 62: 6.2 Unicode Concepts Unicode encodi
Page 63 and 64: artificial characters which will be
Page 65 and 66: width (x, y) beta fontsize baseline
Page 67 and 68: 6.4 Support for Chinese, Japanese,
Page 69 and 70: Options for text filtering. There a
Page 71 and 72: 6.6 Content Analysis PDF documents
Page 73 and 74: Dehyphenation. Hyphenated words at
Page 75 and 76: Table 6.3 Document styles docstyle=
Page 77 and 78: Fig. 6.5 Sample font reports create
Page 79 and 80: glyphmapping {{fontname=Warnock* to
Page 81 and 82: 7 Image Extraction 7.1 Image Extrac
Page 83 and 84: 7.2 Image Geometry Using TET_get_im
Page 85: 7.3 Image Analysis Image merging. S
Page 89 and 90: 8 TET Markup Language (TETML) 8.1 C
Page 91 and 92: Depending on the sele
Page 93 and 94: You can specify the amount of text
Page 95 and 96: Table 8.3 TETML elements TETML elem
Page 97 and 98: 8.4 Transforming TETML with XSLT Ve
Page 99 and 100: Run the program as follows: nxslt3.
Page 101 and 102: 8.5 XSLT Samples The TET distributi
Page 103 and 104: Alphabetical list of words in the d
Page 105 and 106: 9 The pCOS Interface The pCOS (PDFl
Page 107 and 108: 9.2 Handling Basic PDF Data Types p
Page 109 and 110: 9.3 Composite Data Structures and I
Page 111 and 112: Path prefixes. Prefixes can be used
Page 113 and 114: Table 9.3 Universal pseudo objects
Page 115 and 116: Table 9.4 Pseudo objects for PDF ob
Page 117 and 118: Table 9.5 Pseudo objects for resour
Page 119 and 120: 9.6 Encrypted PDF Documents pCOS su
Page 121 and 122: 10 TET Library API Reference 10.1 O
Page 123 and 124: 10.2 General Functions Perl PHP res
Page 125 and 126: Returns Scope Bindings The converte
Page 127 and 128: 10.3 Exception Handling C++ string
Page 129 and 130: 10.4 Document Functions C++ int ope
Page 131 and 132: Table 10.3 Document options for TET
Page 133 and 134: C++ C int open_document_callback(vo
Page 135 and 136: Table 10.5 Page options for TET_ope
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Table 10.6 Suboptions for the conte
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Table 10.7 Suboptions for the layou
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Table 10.9 Suboptions for the struc
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C++ const TET_char_info *get_char_i
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10.7 Image Retrieval Functions C++
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C++ int write_image_file(int doc, i
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10.8 TET Markup Language (TETML) Fu
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10.9 Option Handling C++ void set_o
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10.10 pCOS Functions The full pCOS
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If the object has type stream all f
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A TET Library Quick Reference The f
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B Revision History Revision history
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unsupported types 87 XMP metadata 8
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PDFlib Text Extraction Toolkit (TET) Manual

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