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So you want to parse a PDF?

eliot-jones.com

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Re: So you want to parse a PDF?

#51

Post by icedchai »

reactordev wrote: post #37
throwaway4496 wrote: post #20

Earlier quoted context omitted.

How is it reasonable to render the PDF, rasterize it, OCR it, use AI, instead of just using the "quality implementation" to actually get structured data out? Sounds like "I don't know programming, so I will just use AI".

As someone who had to parse form data from a pdf, where the pdf author named the inputs TextField1 TextField2 TextFueld3 etc. Misspellings, default names, a mixture, home brew naming schemes, meticulous schemes, I’ve seen it all. It’s definitely easier to just rasterize it and OCR it.

Same. Then someone edits the form and changes the names of several inputs, obsoleting much of the previous work, some of which still needs to be maintained because multiple versions are floating around.

Re: So you want to parse a PDF?

#52

Post by sbrother »

BobbyTables2 wrote: post #45
diptanu wrote: post #15

Disclaimer - Founder of Tensorlake, we built a Document Parsing API for developers. This is exactly the reason why Computer Vision approaches for parsing PDFs works so well in the real world. Relying on metadata in files just doesn't scale across different source of PDFs. We convert PDFs to images, run a layout understanding model on them first, and then apply specialized models like text recognition and table recogn…

Kinda funny. Printing a PDF and scanning it for an email it would normally be worthy of major ridicule. But you’re basically doing that to parse it. I get it, have heard of others doing the same. Just seems damn frustrating that such is necessary. The world sure doesn’t parse HTML that way!

I've built document parsing pipelines for a few clients recently, and yeah this approach yields way superior results using what's currently available. Which is completely absurd, but here we are.

Re: So you want to parse a PDF?

#53

Post by anon-3988 »

Last weekend I was trying to convert some PDF of Upanishads which contains some Sanskrit and English word.

By god its so annoying, I don't think I would be able to without the help of Claude Code with it just reiterating different libraries and methods over and over again.

Can we just write things in markdown from now on? I really, really, really, don't care that the images you put is nicely aligned to the right side and every is boxed together nicely.

Just give me the text and let me render it however I want on my end.

Re: So you want to parse a PDF?

#54

Post by [deleted] »

diptanu wrote: post #15

Disclaimer - Founder of Tensorlake, we built a Document Parsing API for developers. This is exactly the reason why Computer Vision approaches for parsing PDFs works so well in the real world. Relying on metadata in files just doesn't scale across different source of PDFs. We convert PDFs to images, run a layout understanding model on them first, and then apply specialized models like text recognition and table recogn…

[deleted]

Re: So you want to parse a PDF?

#56

Post by daemonologist »

throwaway4496 wrote: post #18
diptanu wrote: post #15

Disclaimer - Founder of Tensorlake, we built a Document Parsing API for developers. This is exactly the reason why Computer Vision approaches for parsing PDFs works so well in the real world. Relying on metadata in files just doesn't scale across different source of PDFs. We convert PDFs to images, run a layout understanding model on them first, and then apply specialized models like text recognition and table recogn…

So you parse PDFs, but also OCR images, to somehow get better results? Do you know you could just use the parsing engine that renders the PDF to get the output? I mean, why raster it, OCR it, and then use AI? Sounds creating a problem to use AI to solve it.

Yes, but a lot of the improvement is coming from layout models and/or multimodal LLMs operating directly on the raster images, as opposed to via classical OCR. This gets better results because the PDF format does not necessarily impart reading order or semantic meaning; the only way to be confident you're reading it like a human would is to actually do so - to render it out.

Another thing is that most document parsing tasks are going to run into a significant volume of PDFs which are actually just a bunch of scans/images of paper, so you need to build this capability anyways.

TL;DR: PDFs are basically steganography

Re: So you want to parse a PDF?

#57

Post by gcanyon »

The answer seems obvious to me:

   1. PDFs support arbitrary attached/included metadata in whatever format you like.
   2. So everything that produces PDFs should attach the same information in a machine-friendly format.
   3. Then everyone who wants to "parse" the PDF can refer to the metadata instead.
From a practical standpoint: my first name is Geoff. Half the resume parsers out there interpret my name as "Geo" and "ff" separately. Because that's how the text gets placed into the PDF. This happens out of multiple source applications.

Re: So you want to parse a PDF?

#58

Post by diptanu »

throwaway4496 wrote: post #20
bee_rider wrote: post #17

Earlier quoted context omitted.

Seems like a fairly reasonable decision given all the high quality implementations out there.

How is it reasonable to render the PDF, rasterize it, OCR it, use AI, instead of just using the "quality implementation" to actually get structured data out? Sounds like "I don't know programming, so I will just use AI".

There are many cases images are exported as PDFs. Think invoices or financial statements that people send to financial services companies. Using layout understanding and OCR based techniques leads to way better results than writing a parser which relies on the files metadata.

The other thing is segmenting a document and linearizing it so that an LLM can understand the content better. Layout understanding helps with figuring out the natural reading order of various blocks of the page.

Re: So you want to parse a PDF?

#59

Post by diptanu »

koakuma-chan wrote: post #35
throwaway4496 wrote: post #20

Earlier quoted context omitted.

How is it reasonable to render the PDF, rasterize it, OCR it, use AI, instead of just using the "quality implementation" to actually get structured data out? Sounds like "I don't know programming, so I will just use AI".

I think it's reasonable because their models are probably trained on images, and not whatever "structured data" you may get out of a PDF.

Yes this! We training it on a ton of diverse document images to learn reading order and layouts of documents :)

Re: So you want to parse a PDF?

#60

Post by diptanu »

Alex3917 wrote: post #19
diptanu wrote: post #15

Disclaimer - Founder of Tensorlake, we built a Document Parsing API for developers. This is exactly the reason why Computer Vision approaches for parsing PDFs works so well in the real world. Relying on metadata in files just doesn't scale across different source of PDFs. We convert PDFs to images, run a layout understanding model on them first, and then apply specialized models like text recognition and table recogn…

> This is exactly the reason why Computer Vision approaches for parsing PDFs works so well in the real world. One of the biggest benefits of PDFs though is that they can contain invisible data. E.g. the spec allows me to embed cryptographic proof that I've worked at the companies I claim to have worked at within my resume. But a vision-based approach obviously isn't going to be able to capture that.

Yeah we don't handle this yet.
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