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S
Smogshaik
Participating Frequently
June 11, 2020
Question

Is the toUnicode-cmap editable?

  • June 11, 2020
  • 1 reply
  • 2975 views

This may sound very specific and advanced, but I really don't know much about PDFs yet.

 

What I want to do: take an existing PDF and export it in Adobe Acrobat Pro DC conforming to PDF/A2u standards. These are standards for the long-term archiving of PDFs. No experience with these standards is necessary to answer my question though, I think.

 

Some PDFs are unable to be exported that way because they have some toUnicode mappings that don't conform to the standards. More specifically: "'ToUnicode'-cmap contains zero as a Unicode value". This is not a huge issue I reckon, but I'd still like my PDFs to conform to the standard at the end.

 

Is there any way to access these mappings? I imagine them as a simple dictionary with key-value pairs of glyphs and Unicode values. As such, it should be easy to change. I can't find anything in the Acrobat though.

 

Can anyone help me with this please?

This topic has been closed for replies.

1 reply

T
Test Screen Name
Legend
June 11, 2020

In PDF internals, a ToUnicode map is a text stream embedded in the PDF. Almost always compressed so it will not be simply editable or readable without using software that can decode PDF structures. 

S
SmogshaikAuthor
Participating Frequently
June 11, 2020

Thank you for the reply! Do you happen to know of any software that can decode those structures? I would assume only Adobe software can do that truly well. Since I'm a bit of a programmer, I'm keen on learning more!

T
Test Screen Name
Legend
June 12, 2020

The format of PDF is not a secret. It's described in this 1000 page book: https://www.adobe.com/content/dam/acom/en/devnet/pdf/PDF32000_2008.pdf

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