support for tagged PDFs (PDF/UA, PDF/A)

[tobwen]

feature request

Would it be possible to add support for tagged PDFs, f.e. used in PDF/UA (accessibility)?

PDF specification

All the specifications have been released for free (no costs!):

• https://pdfa.org/resource/iso-32000-pdf/
• https://pdfa.org/game-changing-new-free-specification-enables-interoperable-reuse-and-accessibility-for-pdf/

additional information

When creating accessible PDFs, some processes such as retagging or moving tags (e.g. footnotes) must be done manually via Acrobat or a few compatible editors. It would be great if this could be done via JSON, for example.

I can provide all kinds of demo files to support this endeavor.

[hhrutter]

Hello!

I put this in the pipeline.
Can you provide maybe one or two small, representative demo files?

[tobwen]

I put this in the pipeline. Can you provide maybe one or two small, representative demo files?

Sure, I'll create some nice demo files.

I'm not in a financial position to support the whole thing financially (at least not beyond the occasional pizza or maybe a small pizza oven). But I will do my best to contribute details, data and testing time.

[tobwen]

hint

I've handcrafted a tagged file. This isn't PDF/UA-valid, since I didn't embedd the font and didn't add stuff like XMP. That makes it easier to understand, how tagged PDFs work.

If you're interested, I can also supply full featured files, with complicated tables. But here it is more difficult to create a "plain" version.

untagged PDF

%PDF-1.4
%µ¶

1 0 obj
<<
  /Type /Catalog
  /Pages 2 0 R
>>
endobj

2 0 obj
<<
  /Type /Pages
  /Kids [ 3 0 R ]
  /Count 1
>>
endobj

3 0 obj
<<
  /Type /Page
  /Parent 2 0 R
  /MediaBox [ 0 0 612 792 ]
  /Resources <<
    /Font <<
      /F0 4 0 R
    >>
  >>
  /Contents 5 0 R
>>
endobj

4 0 obj
<<
  /Type /Font
  /Subtype /Type1
  /BaseFont /Helvetica
>>
endobj

5 0 obj
<<
  /Length 89
>>
stream
BT
/F0 12 Tf
100 700 Td
(Hello, this is line 1.) Tj
0 -20 Td
(And this is line 2.) Tj
ET

endstream
endobj

xref
0 6
0000000000 65536 f 
0000000016 00000 n 
0000000070 00000 n 
0000000136 00000 n 
0000000291 00000 n 
0000000368 00000 n 

trailer
<<
  /Size 6
  /Root 1 0 R
>>
startxref
510
%%EOF

tagged PDF

%PDF-1.4
%µ¶

1 0 obj
<<
  /Pages 2 0 R
  /StructTreeRoot 5 0 R
  /Type /Catalog
>>
endobj

2 0 obj
<<
  /Count 1
  /Kids [ 3 0 R ]
  /Type /Pages
>>
endobj

3 0 obj
<<
  /Contents 10 0 R
  /MediaBox [ 0 0 612 792 ]
  /Parent 2 0 R
  /Resources <<
    /Font <<
      /F0 4 0 R
    >>
  >>
  /StructParents 0
  /Type /Page
>>
endobj

4 0 obj
<<
  /BaseFont /Helvetica
  /Subtype /Type1
  /Type /Font
>>
endobj

5 0 obj
<<
  /K 6 0 R
  /ParentTree 9 0 R
  /ParentTreeNextKey 1
  /Type /StructTreeRoot
>>
endobj

6 0 obj
<<
  /K [ 7 0 R 8 0 R ]
  /Lang (en_US)
  /P 5 0 R
  /S /Document
  /T ()
>>
endobj

7 0 obj
<<
  /K 0
  /P 6 0 R
  /Pg 3 0 R
  /S /P
  /T ()
>>
endobj

8 0 obj
<<
  /K 1
  /P 6 0 R
  /Pg 3 0 R
  /S /P
  /T ()
>>
endobj

9 0 obj
<<
  /Nums [ 0 [ 7 0 R 8 0 R ] ]
>>
endobj

10 0 obj
<<
  /Length 139
>>
stream
q
/P<</MCID 0>>BDC
BT
/F0 12 Tf
100 700 Td
(Hello, this is line 1.)Tj
EMC
/P<</MCID 1>>BDC
20 TL
0 -20 Td
(And this is line 2.)Tj
EMC
ET
Q

endstream
endobj

xref
0 11
0000000000 65536 f 
0000000016 00000 n 
0000000094 00000 n 
0000000160 00000 n 
0000000335 00000 n 
0000000412 00000 n 
0000000512 00000 n 
0000000605 00000 n 
0000000673 00000 n 
0000000741 00000 n 
0000000793 00000 n 

trailer
<<
  /Size 11
  /Root 1 0 R
>>
startxref
987
%%EOF

[hhrutter]

Please upload the file for analysis if you can.
Thanks for using pdfcpu 💚

[tobwen]

Please upload the file for analysis if you can.

untagged.pdf
tagged.pdf