Structure of a PDF file

Question

For a small project I have to parse pdf files and take a specific part of them  a simple chain of characters   I d like to use python to do this and I ve found several libraries that are capable of doing what I want in some ways   But now after a few researches  I m wondering what is the real structure of a pdf file  does anyone know if there is a spec or some explanations anywhere online  I ve found a link on adobe but it seems that it s a dead link

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Extracting text from PDF is a hard problem because PDF has such a layout-oriented structure   You can see the docs and source code of my barely-successful attempt on CPAN  my implementation is in Perl    The PDF data structure is very cool and well designed  but it s easier to write than read

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To extract text from a PDF  try this on Linux  BSD  etc  machine or use Cygwin if on Windows   pdfinfo -layout some pdf file pdf   A plain text file named some pdf file txt is created   The simpler the PDF file layout  the more straightforward the  txt file output will be   Hexadecimal characters are frequently present in the  txt file output and will look strange in text editors   These hexadecimal characters usually represent curly single and double quotes  bullet points  hyphens  etc  in the PDF   To see the context where the hexadecimal characters appear  run this grep command  and keep the original PDF handy to see what character the codes represent in the PDF   grep -a --color always       0-9  0-9  0-9   some pdf file txt   This will provide a unique list of the different octal codes in the document   grep -ao       0-9  0-9  0-9   some pdf file txt sort uniq   To convert these hexadecimal characters to ASCII equivalents  a combination of grep  sed  and bc can be used  I ll post the procedure to do that soon

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When I first started working with PDF  I found the PDF reference very hard to navigate  It might help you to know that the overview of the file structure is found in syntax  and what Adobe call the document structure is the object structure and not the file structure   That is also found in Syntax   The description of operators is hidden away in Appendix A - very useful for understanding what is happening in content streams   If you ever have the pain of working with colour spaces you will find that hidden in Graphics   Hopefully these pointers will help you find things more quickly than I did   If you are using windows  pdftron CosEdit allows you to browse the object structure to understand it   There is a free demo available that allows you to examine the file but not save it

User · Answer

To extract text from a PDF  try this on Linux  BSD  etc  machine or use Cygwin if on Windows   pdfinfo -layout some pdf file pdf   A plain text file named some pdf file txt is created   The simpler the PDF file layout  the more straightforward the  txt file output will be   Hexadecimal characters are frequently present in the  txt file output and will look strange in text editors   These hexadecimal characters usually represent curly single and double quotes  bullet points  hyphens  etc  in the PDF   To see the context where the hexadecimal characters appear  run this grep command  and keep the original PDF handy to see what character the codes represent in the PDF   grep -a --color always       0-9  0-9  0-9   some pdf file txt   This will provide a unique list of the different octal codes in the document   grep -ao       0-9  0-9  0-9   some pdf file txt sort uniq   To convert these hexadecimal characters to ASCII equivalents  a combination of grep  sed  and bc can be used  I ll post the procedure to do that soon

User · Answer

If You want to parse PDF using Python please have a look at PDFMINER  This is the best library to parse PDF files till date

User · Answer

Extracting text from PDF is a hard problem because PDF has such a layout-oriented structure   You can see the docs and source code of my barely-successful attempt on CPAN  my implementation is in Perl    The PDF data structure is very cool and well designed  but it s easier to write than read

User · Answer

You need the PDF Reference manual to start reading about the details and structure of PDF files  I suggest to start with version 1 7   On windows I used a free tool PDF Analyzer to see the internal structure of PDF files   This will help in your understanding when reading the reference manual      I m affiliated with PDF Analyzer  no intention to promote

User · Answer

One way to get some clues is to create a PDF file consisting of a blank page   I have CutePDF Writer on my computer  and made a blank Wordpad document of one page   Printed to a  pdf file  and then opened the  pdf file using Notepad   Next  use a copy of this file and eliminate lines or blocks of text that might be of interest  then reload in Acrobat Reader   You d be surprised at how little information is needed to make a working one-page PDF document   I m trying to make up a spreadsheet to create a PDF form from code

User · Answer

If You want to parse PDF using Python please have a look at PDFMINER  This is the best library to parse PDF files till date

User · Answer

This may help shed a little light   from page 11 of PDF32000 book      PDF syntax is best understood by considering it as four parts  as shown in Figure 1           Objects  A PDF document is a data structure composed from a small set of basic types of data objects      Sub-clause 7 2   Lexical Conventions   describes the character set used to write objects and other    syntactic elements  Sub-clause 7 3   Objects   describes the syntax and essential properties of the objects    Sub-clause 7 3 8   Stream Objects   provides complete details of the most complex data type  the stream   object           File structure  The PDF file structure determines how objects are stored in a PDF file  how they are     accessed  and how they are updated  This structure is independent of the semantics of the objects  Sub-    clause 7 5   File Structure   describes the file structure  Sub-clause 7 6   Encryption   describes a file-level   mechanism for protecting a document   s contents from unauthorized access           Document structure  The PDF document structure specifies how the basic object types are used to     represent components of a PDF document  pages  fonts  annotations  and so forth  Sub-clause 7 7      Document Structure   describes the overall document structure  later clauses address the detailed   semantics of the components           Content streams  A PDF content stream contains a sequence of instructions describing the appearance of     a page or other graphical entity  These instructions  while also represented as objects  are conceptually    distinct from the objects that represent the document structure and are described separately  Sub-clause   7 8   Content Streams and Resources   discusses PDF content streams and their associated resources    Looks like navigating a PDF file will require a little more than a passing effort

User · Answer

I m trying to do pretty much the same thing  The PDF reference is a very difficult document to read  This tutorial is a better start I think

User · Answer

Here is a link to Adobe s reference material  http   www adobe com devnet pdf pdf reference html  You should know though that PDF is only about presentation  not structure  Parsing will not come easy

User · Answer

When I first started working with PDF  I found the PDF reference very hard to navigate  It might help you to know that the overview of the file structure is found in syntax  and what Adobe call the document structure is the object structure and not the file structure   That is also found in Syntax   The description of operators is hidden away in Appendix A - very useful for understanding what is happening in content streams   If you ever have the pain of working with colour spaces you will find that hidden in Graphics   Hopefully these pointers will help you find things more quickly than I did   If you are using windows  pdftron CosEdit allows you to browse the object structure to understand it   There is a free demo available that allows you to examine the file but not save it

User · Answer

I found the GNU Introduction to PDF to be helpful in understanding the structure  It includes an easily readable example PDF file that they describe in complete detail   Other helpful links    PDF Succinctly book is longer and has helpful pictures  Introduction to the Insides of PDF is a presentation that isn t as in-depth but gives a quick overview and has lots of pictures

User · Answer

Here is a link to Adobe s reference material  http   www adobe com devnet pdf pdf reference html  You should know though that PDF is only about presentation  not structure  Parsing will not come easy

User · Answer

One way to get some clues is to create a PDF file consisting of a blank page   I have CutePDF Writer on my computer  and made a blank Wordpad document of one page   Printed to a  pdf file  and then opened the  pdf file using Notepad   Next  use a copy of this file and eliminate lines or blocks of text that might be of interest  then reload in Acrobat Reader   You d be surprised at how little information is needed to make a working one-page PDF document   I m trying to make up a spreadsheet to create a PDF form from code

User · Answer

Here s the raw reference of PDF 1 7  and here s an article describing the structure of a PDF file  If you use Vim  the pdftk plugin is a good way to explore the document in an ever-so-slightly less raw form  and the pdftk utility itself  and its GPL source  is a great way to tease documents apart

User · Answer

Didier have a tool to parse the PDF   http   didierstevens com files software pdf-parser V0 4 3 zip  or here   http   blog didierstevens com programs pdf-tools  which cataloged several related pdf-analysis tools   Another tool is here   http   mshahzadlatif wordpress com 2011 09 28 view-pdf-structure-using-adobe-acrobat-or-a-free-tool-called-pdfxplorer

User · Answer

I m trying to do pretty much the same thing  The PDF reference is a very difficult document to read  This tutorial is a better start I think

User · Answer

Here is a link to Adobe s reference material  http   www adobe com devnet pdf pdf reference html  You should know though that PDF is only about presentation  not structure  Parsing will not come easy

User · Answer

I found the GNU Introduction to PDF to be helpful in understanding the structure  It includes an easily readable example PDF file that they describe in complete detail   Other helpful links    PDF Succinctly book is longer and has helpful pictures  Introduction to the Insides of PDF is a presentation that isn t as in-depth but gives a quick overview and has lots of pictures

User · Answer

Here s the raw reference of PDF 1 7  and here s an article describing the structure of a PDF file  If you use Vim  the pdftk plugin is a good way to explore the document in an ever-so-slightly less raw form  and the pdftk utility itself  and its GPL source  is a great way to tease documents apart

User · Answer

When I first started working with PDF  I found the PDF reference very hard to navigate  It might help you to know that the overview of the file structure is found in syntax  and what Adobe call the document structure is the object structure and not the file structure   That is also found in Syntax   The description of operators is hidden away in Appendix A - very useful for understanding what is happening in content streams   If you ever have the pain of working with colour spaces you will find that hidden in Graphics   Hopefully these pointers will help you find things more quickly than I did   If you are using windows  pdftron CosEdit allows you to browse the object structure to understand it   There is a free demo available that allows you to examine the file but not save it

User · Answer

You need the PDF Reference manual to start reading about the details and structure of PDF files  I suggest to start with version 1 7   On windows I used a free tool PDF Analyzer to see the internal structure of PDF files   This will help in your understanding when reading the reference manual      I m affiliated with PDF Analyzer  no intention to promote

User · Answer

This may help shed a little light   from page 11 of PDF32000 book      PDF syntax is best understood by considering it as four parts  as shown in Figure 1           Objects  A PDF document is a data structure composed from a small set of basic types of data objects      Sub-clause 7 2   Lexical Conventions   describes the character set used to write objects and other    syntactic elements  Sub-clause 7 3   Objects   describes the syntax and essential properties of the objects    Sub-clause 7 3 8   Stream Objects   provides complete details of the most complex data type  the stream   object           File structure  The PDF file structure determines how objects are stored in a PDF file  how they are     accessed  and how they are updated  This structure is independent of the semantics of the objects  Sub-    clause 7 5   File Structure   describes the file structure  Sub-clause 7 6   Encryption   describes a file-level   mechanism for protecting a document   s contents from unauthorized access           Document structure  The PDF document structure specifies how the basic object types are used to     represent components of a PDF document  pages  fonts  annotations  and so forth  Sub-clause 7 7      Document Structure   describes the overall document structure  later clauses address the detailed   semantics of the components           Content streams  A PDF content stream contains a sequence of instructions describing the appearance of     a page or other graphical entity  These instructions  while also represented as objects  are conceptually    distinct from the objects that represent the document structure and are described separately  Sub-clause   7 8   Content Streams and Resources   discusses PDF content streams and their associated resources    Looks like navigating a PDF file will require a little more than a passing effort

User · Answer

Didier have a tool to parse the PDF   http   didierstevens com files software pdf-parser V0 4 3 zip  or here   http   blog didierstevens com programs pdf-tools  which cataloged several related pdf-analysis tools   Another tool is here   http   mshahzadlatif wordpress com 2011 09 28 view-pdf-structure-using-adobe-acrobat-or-a-free-tool-called-pdfxplorer

User · Answer

Here is a link to Adobe s reference material  http   www adobe com devnet pdf pdf reference html  You should know though that PDF is only about presentation  not structure  Parsing will not come easy

User · Answer

When I first started working with PDF  I found the PDF reference very hard to navigate  It might help you to know that the overview of the file structure is found in syntax  and what Adobe call the document structure is the object structure and not the file structure   That is also found in Syntax   The description of operators is hidden away in Appendix A - very useful for understanding what is happening in content streams   If you ever have the pain of working with colour spaces you will find that hidden in Graphics   Hopefully these pointers will help you find things more quickly than I did   If you are using windows  pdftron CosEdit allows you to browse the object structure to understand it   There is a free demo available that allows you to examine the file but not save it

User · Answer

Here s the raw reference of PDF 1 7  and here s an article describing the structure of a PDF file  If you use Vim  the pdftk plugin is a good way to explore the document in an ever-so-slightly less raw form  and the pdftk utility itself  and its GPL source  is a great way to tease documents apart

User · Answer

Extracting text from PDF is a hard problem because PDF has such a layout-oriented structure   You can see the docs and source code of my barely-successful attempt on CPAN  my implementation is in Perl    The PDF data structure is very cool and well designed  but it s easier to write than read

User · Answer

Here s the raw reference of PDF 1 7  and here s an article describing the structure of a PDF file  If you use Vim  the pdftk plugin is a good way to explore the document in an ever-so-slightly less raw form  and the pdftk utility itself  and its GPL source  is a great way to tease documents apart

User · Answer

Extracting text from PDF is a hard problem because PDF has such a layout-oriented structure   You can see the docs and source code of my barely-successful attempt on CPAN  my implementation is in Perl    The PDF data structure is very cool and well designed  but it s easier to write than read

[pdf] Structure of a PDF file?

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