3 ms·

can somebody explain? I already can create PDF from latex, what does this repo add to it?

anewhnaccount3 2y ago
In the future better accessibility for screen readers of text (paragraph breaks), images (alt text), tables (control of reading order), and math formulae. It's up to the pdf readers too though.
lxgr 2y ago
PDF/UA makes PDFs accessible, which can otherwise be very hard to parse for screenreaders or display software that wants to reflow them (e.g. for reading them on small displays). Without special hints (that are ignored by regular PDF readers or printers), PDF is essentially a vector graphics format, and any of these tasks amount to an exercise in OCR. This is a somewhat little-known fact about PDFs, since many viewers do in fact implement many of these OCR-like heuristics to provide features such as text selection, search etc. that make it look a lot like a text-based format, but it really is a vector graphics format at heart. PDF/UA makes this a bit easier. As an example, consider a multiple column layout, as is often used in scientific articles. PDF-creating software not concerned with accessibility might just intersperse all columns line by line (i.e. present text in presentational left-to-right, top-to-bottom fashion), but it could just as well achieve the same outcome by drawing column by column in semantic order. Beyond encouraging that, I believe PDF/UA also defines a bunch of (invisible) metadata tags that readers can use to figure out semantic structuring of a document.
- dguest 2y ago
  Sounds like this would massively simplify converting scientific articles back to HTML or text. Seriously, I know of one experiment that has O(thousands) of papers as latex source, which they publish as PDFs and which (more recently) they convert back to markdown with some ML-based image to text engine. All so that it can be fed to a vector database to make searching easier, of course. PDFs are a terrible format for machine readable information (and thus for reproducible science), but they are the currency of the scientific community and as such will be the standard output for the foreseeable future.
  - nabla9 2y ago
    >PDFs are a terrible format for machine readable information was terrible format. PDF 2.0 Tagged PDF has MathML support, Index, Quote, BibEntry, Title, lists, tables, .... you can derive HTML from PDF if it's fully tagged. PDF also support displaying and print production better than anything.
    - elric 2y ago
      I'd argue it still is a terrible format for anything other than printing. It values form over function. I mean this makes sense for laying out papers to be published into a physical journal, but it doesn't make as much sense for other purposes. I'd much rather have plain text, or markdown, or asciidoc than PDF or HTML. It works everywhere. And support for embedded mathematical typesetting is a solved problem.
      - tjoff 2y ago
        I agree plain text has a lot of appeal. But support for embedded mathematical typesetting, images etc, being solved feels like a stretch. I mean sure, you can do it, but now you are on the other end of function over form. I feel like PDFs are, for tons of usecases, the best we've got. The alternative isn't markdown, it's usually .docx.
        SSLy 2y ago
        The actual alternative is EPUBs
        lxgr 2y ago
        I love ePub, but I also have to admit that the viewer experience for non-books is really not quite there yet. Most viewers on iOS, macOS, Linux and Android that I've tried are very tied to the idea of all ePubs being ebooks and insist on managing them in their own library, don't optimize latency to first page rendered (because they usually index and cache a bunch of stuff for a "newly opened book", assuming you'll be reading it over the course of days/weeks) etc. For example, on macOS, the default app associated with ePub is Apple Books, but to be able to use technical papers in ePub format, I really need something like Preview.app (and that doesn't support them). (In that way, the situation is very similar to JPEG XL: macOS supports them in quick view, but only Safari can actually open them...)

In the future better accessibility for screen readers of text (paragraph breaks), images (alt text), tables (control of reading order), and math formulae. It's up to the pdf readers too though.

lxgr 2y ago

PDF/UA makes PDFs accessible, which can otherwise be very hard to parse for screenreaders or display software that wants to reflow them (e.g. for reading them on small displays). Without special hints (that are ignored by regular PDF readers or printers), PDF is essentially a vector graphics format, and any of these tasks amount to an exercise in OCR. This is a somewhat little-known fact about PDFs, since many viewers do in fact implement many of these OCR-like heuristics to provide features such as text selection, search etc. that make it look a lot like a text-based format, but it really is a vector graphics format at heart. PDF/UA makes this a bit easier. As an example, consider a multiple column layout, as is often used in scientific articles. PDF-creating software not concerned with accessibility might just intersperse all columns line by line (i.e. present text in presentational left-to-right, top-to-bottom fashion), but it could just as well achieve the same outcome by drawing column by column in semantic order. Beyond encouraging that, I believe PDF/UA also defines a bunch of (invisible) metadata tags that readers can use to figure out semantic structuring of a document.

dguest 2y ago
Sounds like this would massively simplify converting scientific articles back to HTML or text. Seriously, I know of one experiment that has O(thousands) of papers as latex source, which they publish as PDFs and which (more recently) they convert back to markdown with some ML-based image to text engine. All so that it can be fed to a vector database to make searching easier, of course. PDFs are a terrible format for machine readable information (and thus for reproducible science), but they are the currency of the scientific community and as such will be the standard output for the foreseeable future.
- nabla9 2y ago
  >PDFs are a terrible format for machine readable information was terrible format. PDF 2.0 Tagged PDF has MathML support, Index, Quote, BibEntry, Title, lists, tables, .... you can derive HTML from PDF if it's fully tagged. PDF also support displaying and print production better than anything.
  - elric 2y ago
    I'd argue it still is a terrible format for anything other than printing. It values form over function. I mean this makes sense for laying out papers to be published into a physical journal, but it doesn't make as much sense for other purposes. I'd much rather have plain text, or markdown, or asciidoc than PDF or HTML. It works everywhere. And support for embedded mathematical typesetting is a solved problem.
    - tjoff 2y ago
      I agree plain text has a lot of appeal. But support for embedded mathematical typesetting, images etc, being solved feels like a stretch. I mean sure, you can do it, but now you are on the other end of function over form. I feel like PDFs are, for tons of usecases, the best we've got. The alternative isn't markdown, it's usually .docx.
      - SSLy 2y ago
        The actual alternative is EPUBs
        lxgr 2y ago
        I love ePub, but I also have to admit that the viewer experience for non-books is really not quite there yet. Most viewers on iOS, macOS, Linux and Android that I've tried are very tied to the idea of all ePubs being ebooks and insist on managing them in their own library, don't optimize latency to first page rendered (because they usually index and cache a bunch of stuff for a "newly opened book", assuming you'll be reading it over the course of days/weeks) etc. For example, on macOS, the default app associated with ePub is Apple Books, but to be able to use technical papers in ePub format, I really need something like Preview.app (and that doesn't support them). (In that way, the situation is very similar to JPEG XL: macOS supports them in quick view, but only Safari can actually open them...)