back to article It's powered by a mega-corp AI, it has a Liquid Mode, but it's not a T-1000. It's Adobe's PDF auto-reflow for mobile

Adobe has introduced Liquid Mode into its PDF reader for Android and iOS, the intent being to make reading PDF documents on mobile a less painful experience. Adobe’s Portable Document Format (PDF) dates from 1993, based on the PostScript language used to describe documents accurately to printing. A PDF document should as far …

  1. Mage

    RE: Ideal to proof read before printing

    Not if it's reflowing on a small screen.

    The ENTIRE point of PDF is to proof for Printing. Or Print. You need a big screen.

    We have two superior techs to read documents on small screens: The epub based ebook (a Kindle AZW/KF8 format is basically the same) or HTML.

    No-one needs this and it won't work for many existing PDFs. It will encourage idiots to use PDFs when they ought to produce ebooks (PDFs can be books in electronic form, they are NOT eBooks) or HTML. The only sensible use cases for PDFs are to proof something for print (so it CAN NOT be reflowed!) or to distribute for print or as a wrapper for a scanned multipage document, superior to multipage TIF, that can optionally have OCR for search. PDF forms are a stupid evil invention.

    1. Dave 126 Silver badge

      Re: RE: Ideal to proof read before printing

      > No-one needs this

      Yes we do. We, the people who on occasion want to read a PDF document whilst on the go, have no choice over the format we find it in. Remember - a huge number of instruction manuals are most easily found in PDF format.

      Your points about publishers choosing more suitable formats is valid, but that doesn't address the fact that there are millions of existing PDFs on the web, some of which might just have the information I need to fix something.

      Should we need an Adobe account to read PDFs on a small screen in a sane fashion? No, of course not. But some sort of text reflow - or even just more intelligent zooming and scrolling for common two-column PDFs - is very useful indeed.

      It is that for that reason that use the Gaaiho PDF reader on my Adroid phone.

      ( I haven't tested Gaaiho Reader extensively, but I was driven to try it out after being frustrated by the very issues Adobe are only now claiming to address).

      1. Anonymous Coward
        Anonymous Coward

        Re: RE: Ideal to proof read before printing

        I think the point is that it *cannot* work for a lot of PDFs.

        PDF is a wrapper format - the contents can be a sequence of a load of words/letters, in which case liquid mode has a chance of working, or it can be an image of a page, in which case it will not work.

        The clue about whether it will work or not on any given document would be to try and copy an line of text out of the document: if you can copy the text and paste it into notepad, it'll possibly work in liquid mode.

        I don't see how you can proofread something for printing in a format that doesn't exactly represent the printed page that you expect to get at the end of the process. Or has proofreading been reduced to "the author got all the words in the right order"?

        1. Roland6 Silver badge

          Re: RE: Ideal to proof read before printing

          >PDF is a wrapper format - the contents can be a sequence of a load of words/letters, in which case liquid mode has a chance of working,

          Well taking the simplistic approach, "Liquid mode" is just an ePub version of the document. Which can easily be accommodated in the PDF wrapper. (Back in the 90's we were using this approach to retain searchable OCR text of TIFF images within a single PDF document).

          So this would suggest the 'AI' is all about creating that ePub version on the fly or from a hash lookup to see if the document has been previously rendered.

    2. Anonymous Coward
      Anonymous Coward

      Re: RE: Ideal to proof read before printing

      From the description -

      "Files cannot use Liquid Mode if they are more than 200 pages long, more than 10MB, scanned, converted from presentations, or contain “complex layouts” such as tables and charts, invoices, statements and receipts, forms, or “non-standard page sizes”."

      it sounds like it is just OCR smacked around with the "AI" BrandoStick, with the result formatted to fit on the requested screen.

      1. Dave 126 Silver badge

        Re: RE: Ideal to proof read before printing

        To be clear:

        There is a need for a PDF reader to make the reading of existing PDFs easier on mobile screens.

        I did not mean that there was a need for Adobe's specific solution.

        I did mean that that there is a clear problem: reading existing PDFs with the default reader on Android can be a pain. This problem has been partially addressed by PDF readers from 3rd parties that offer text reflow and more zoom and scrolling options.

        Even the above suggestion that PDF text be copied and pasted into a text editor is just more evidence that the problem exists.

        Mage's argument that there is no need for a better PDF reader of any description because PDFs shouldn't be used isn't helpful in the context of, for example, consulting an instruction manual PDF for a washing machine error code. Mage's 'solution' does nothing to make for the millions of extant PDF files on the web easier to read when one doesn't have a big screen to hand.

        1. Tom 7 Silver badge

          Re: RE: Ideal to proof read before printing

          There is a need for PDF readers for phones, as there is a need for Rhunestone anti-grav machines for phones. We need to wean people of paper shaped documents NOW!

    3. Tom 7 Silver badge

      Re: RE: Ideal to proof read before printing

      Theres a reason its called Pointless Document Format.And while it may lool the same on your screen or printer it wont on someone elses. PDF: the Brexit of the internet - does nothing it says on tin.

  2. Nick Ryan Silver badge

    Unfortunately it still won't fix the all too common completely moronic use of PDF documents such as:

    • Where everything is output as images, no text at all (complete usability and accessibility failure)
    • The document character order is different to thevisual character display order (another complete accessiblity failure, but just about usable if crippled in use)
    • Where the document is rendered for a specific orientation, such as rendering two pages side by side to allow the multi page document to be "easier to read on the web" (accessible, but largely unusable)

    1. Greybearded old scrote Silver badge

      I've seen a couple of occasions where a pdf full of scans made some sense.

      One was preserving a manual for abandonware that we were still using. Naturally, I fed that to OCR software, but correcting it afterwards was time consuming.

      The other was for archiving against FOI requests. When I laughed at that it was explained to me that any hand written notes needed to be captured too.

      Hmm, maybe I need two more exceptions to my LARTing comment below.

      1. Nick Ryan Silver badge

        A .PDF full of scans is very different to outputting a text document as an image - that's what I have exception to

    2. Dave 126 Silver badge

      > moronic use of PDF documents such as: Where everything is output as images, no text at all (complete usability and accessibility failure)

      No text is handy when sending, for example, a poster created in Illustrator to a printing agency in PDF format. Converting the text to vector outlines means that you don't have to worry about the printing agency having all the fonts you have used. Obviously in this use case the lack of edibility is not an issue - the creator retains the original document and doesn't want the printer to change anything.

      1. Nick Ryan Silver badge

        That's a fair use case... as long as the exact DPI is adhered to along with all the appropriate colour hinting.

        The alternative is to just embed the font in the document. This has been a standard capability of PDFs for quote some time now.

        I've been on the receiving of tender responses rendered as images (instant very high negative scoring) as well as non-scanned manuals (largely unusable when one cannot search the text).

    3. Anonymous Coward
      Anonymous Coward

      > The document character order is different to the visual character display order (another complete accessiblity failure, but just about usable if crippled in use)

      Word does that on occasion (or used to - haven't looked at the latest versions). Another PDF sin is specifying the exact x,y position of every single character even when the default font metrics are being used so there is no need. (The result is that approx 15 bytes are needed per character when one would do).

      1. Nick Ryan Silver badge

        Oh hell, that's really horrible.

        Sounds similar to what happens when Microsoft Word is used as an HTML editor.

  3. Greybearded old scrote Silver badge

    Just unfit for the purpose

    Basically, anyone who writes pdf for any use case other than print or proofing needs to be re-educated with the biggest LART available. There are multiple formats designed to reflow as needed, although many alleged designers insist on nobbling that functionality in the name of 'pixel perfection.'

    It's been nearly 30 years of the web. It's long past time we dropped what Ted Nelson mocks as, 'paper under glass.'

    1. Anonymous Coward
      Anonymous Coward

      Re: Just unfit for the purpose

      What often happens is that a PDF will be created so that an instruction manual can be printed. End user loses instruction manual. Years later user needs to consult manual. They find it easier to find PDF version on web than to find original hard copy.

    2. Gene Cash Silver badge

      Re: Just unfit for the purpose

      Fuck Jakon Nielsen.

      PDFs are perfect for things like instruction manuals, where things need to be laid out properly and clearly, without web-style stupid shit like the image on one page and the caption on another.

      1. Greybearded old scrote Silver badge

        Re: Just unfit for the purpose

        What is this 'page' of which you speak? That's a squashed tree concept isn't it?

        1. Dan 55 Silver badge

          Re: Just unfit for the purpose

          Would you really like to read e-books without so much as a page break that forever-scroll? It'd be paragraphs all the way down.

      2. Greybearded old scrote Silver badge

        Re: Just unfit for the purpose

        BTW, sensible use of a block level element will group the picture and caption together. Semantic markup and all that.

        1. Roland6 Silver badge

          Re: Just unfit for the purpose

          >BTW, sensible use of a block level element will group the picture and caption together.

          From having had to print webpages (eg. "for your records print this page") it seems many webpage creators don't understand "sensible usage".

          1. Tom 7 Silver badge

            Re: Just unfit for the purpose

            And almost all PDF producers dont understand "sensible usage".

            1. Roland6 Silver badge

              Re: Just unfit for the purpose

              Yes, I suspect in the current era, the problem lies in the tools...

              I use Word/Libre etc. to produce a formatted document, which allows me to link elements together, the problems seem to arise when these documents are converted to some other format ie. PDF and HTML, where this linkage information seems to get lost.

              Given the purpose of PDF is to preserve the look of a printed page across devices and printers, it is generally okay that PDF loses some of the metadata of the original document. It only becomes a problem when you wish to use the PDF as if it were a document format like ODF and Doc, ie. something PDF/Postscript wasn't intended to be used for .

              However, webpage creators don't really have the same excuses; particularly when there is an expectation that the user will want to print the displayed webpage. It p*sses me off that web page producers don't understand the principle that I want not only to be able to display a webpage nicely on my screen, but also at times I want it to 'display' nicely on a series of A4 sized 'screens'. Strangely MS manage this quite well in Word giving the user multiple views of the same content. Interestingly, there are some websites that do understand that people want to print stuff and the print option reformats the content for printing (to printer or PDF).

  4. AMBxx Silver badge

    But is it Flash?

    Could it be a Flash viewer for pdf?

  5. Greybearded old scrote Silver badge

    Another thing

    Phone screens just aren't up to any significant amount of reading. I want a screen the size of a book, and did even before my eyes got this old.

    I've long since used a 10 inch tablet for reading and the cheapest dumbest kirkphone in the shop. The only reason I have an android phone now is that Nokia's flip costs more than an entry level smart phone.

    1. David Roberts

      Re: Another thing

      For you, perhaps.

      I started with a 10 inch tablet, got an 8 inch tablet for a niche use and ended up using that for everything because it was more portable, and that is now falling into disuse because I can use the Kindle reader on my latest phone to read a whole book without discomfort.

      Noting that each new phone has been larger than the last.

  6. Anonymous Coward
    Anonymous Coward


    First, the reflow is coming from a company that has progressively reduced the effectiveness of the Acrobat UI over the last 20 years to the point where I can barely find stuff in the latest release that was once obvious. If they're using AI to put things on the screen in the right place, perhaps they could start with their toolbars.

    Second, as many have pointed out, PDF is a page description language. It excels at positioning things on the page with exactness, and doing so in the correct color. It was never designed for reflow, and the internal format doesn't really allow this. Even now, any product extracting text from PDF has to guess where lines, columns, or even words end - it's very common for a whitespace to be represented with a simple "move cursor" operation rather than any sort of semantic space. PDF text predates Unicode, and it's common to find documents without the requisite structures to identify the meaning of the text. I expect this effort is doomed to reside somewhere between barely-acceptable and outright failure.

    Someone pointed out earlier that the most obvious reflowable document format - HTML - would be a likely contender. You're not the first to raise this, is all I can say. Maybe one day Adobe's wheel-invention subdivision will see the light. Mercifully PDF XMP is no longer with us as of PDF 2.0, so the path is clear to combine a proper reflowable format (HTML) with a proper page description format (PDF).

    Yes, in terms of accessibility it isn't as good as HTML, but that is being worked on. Tagged PDF is very much a thing, and if a document is to be reflowed I would personally be starting by making sure it has the necessary information to do this, rather than relying on the wonders of AI. That means tagged PDF, aka accessible PDFs, aka PDF/UA. If you're generating PDF, do yourself, your customers, search engines and posterity in general a favour and switch to PDF/UA.

    Very, very anon.

    1. Hollerithevo

      Re: Hmm

      I jump up and down all the time on designers and business teams who do not use PDF/UA. Given that it's the law to make everything accessible, they have to get with the programme and do this on PDFs, but each time I say this I get stares from dozens of pairs of dead, uncomprehending, bovine eyes*.

      The fact that tagged PDFs then provide extra benefits for possible re-flowing might finally be the way into their brains. But as most businesses see websites and digital assets such as PDFs just a different and less good way of producing glossy brochures, I am not hopeful.

      *Cows are actually smarter. My apologies to cows everywhere.

  7. DS999 Silver badge

    Relies on the cloud?

    Well I'm out then. Hopefully the iOS native PDF reader will adopt similar functionality, it is annoying having to turn my phone to landscape or pinch/zoom/scroll to read a PDF on a phone so this is a problem that needed to be solved. Just not like Adobe did.

    Seems to me that it should be easy enough to do without requiring either "cloud" or "AI". There also needs to be a simple toggle to enable/disable it, since sometimes you want to view the document in its original form even if that makes it unwieldy - something like Safari's "reader mode" toggle would be perfect for that.

  8. Mike 137 Silver badge

    Wow! Word wrap!

    The fundamental problem is that each line of text in a PDF is a separate container-bounded object. Although this works for static documents, it's a very limiting approach (it makes editing hard as well). A "notional end of line" tag in a continuous data stream that could optionally be ignored (like in every current word processor) would work better, but changing the core mechanism now would render too many documents unreadable.

    Adobe were originally a font foundry and they did that very well. However their every inroad into software applications has been bug ridden, clunky or not future proof (or any combination of these).

  9. ecofeco Silver badge

    FFS. WHY?!

    Why does anyone think working on a tiny screen is somehow productive?

    Dammit I swear the world turns more Idiocracy every day.

    You forgot your laptop? That's on YOU for being an idiot. Along with all the other scenarios where you did not plan ahead.

    1. Hollerithevo

      Re: FFS. WHY?!

      I hate working on a small screen and do not do it, but c'mon: you are living in a science fiction world where you have this small device that you can use to read, look at movies, talk to people face to face, send documents and mail, use as a multi-tool (calculator, dictionary, encyclopedia, play games by yourself or with others, and on and on.

      You can be on a mountain or on a ship or on a train and still talk to your mate in Peru or refresh your memory on spoken Hungarian. And you can actually be pretty productive at work, with a small bit of frustration. Even though I occasionally rage, this is all pretty darn awesome.

  10. Anonymous Coward
    Anonymous Coward

    Who would ever voluntarily install something from adobe any more?

    I mean, seriously? Even viruses are better written.

    1. Anonymous Coward
      Anonymous Coward

      Re: Who would ever voluntarily install something from adobe any more?

      Photoshop is great. But Acrobat is a dog.

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