[libreoffice-users] A word of warning about PDF text

A word of warning about text retrieved from PDF documents.

Recovering text blocks from PDFs is inherently risky.  PDF is a page 
definition format, and so it has no notion of the semantics of the text 
it contains. It places bits of text at certain positions on the page. 
You can create a whole page of text by taking the individual characters 
and their attributes and position on the page, shuffling them, and 
writing them to the file.  That will produce a readable file, but try 
extracting the text from that file. Unless you have a very, very smart 
text extractor that reverse-engineers the process of creating the page, 
then calculates the _visual_ order of the text elements, you will end up 
with gibberish.

_Most_ pdf text, _most_ of the time, is laid on the page in visual 
order, but in even the best-behaved files, you are likely to be surprised.

If you don't _know_ that your PDF text extractor program is completely 
visually accurate by design, don't tell your boss that you can easily 
extract that PDF text, without allowing time for proof-reading every 
page. You will get burned.

I don't know how LO extracts PDF text; perhaps it is very sophisticated. 
I have my doubts.

--
Peter West
"Other seed fell among thorns, and the thorns grew up and choked it..."

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