Musings on Photography

Images in PDF documents

Posted in Adobe InDesign, book design, web issues by Paul Butzi on August 31, 2009

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Colin plaintively asks

As an example of what I mean, the section on images tells you what formats InDesign will accept. It tells you how to move them, put them in frames, link them, wrap text around them and all sorts of other things. It even illustrates the import options for various file types. But what it doesn’t do is suggest which ones to use. Or whether it is best to standardise file specifications (colour space, bit depth etc) outside of InDesign or not. Or whether it is best to place images that are sized perfectly, or oversized. Or output sharpened. Or what the consequences might be of using compressed or uncompressed files. Nor does it give any clues as to where you might find out the answers to these questions.

I have no deep insight here, except for this one observation: if I want something to look good on a screen, I size it to the exact size it will be on screen, then sharpen it at that size so that it looks good on screen. If you import oversized images into InDesign, then if you’ve done any sharpening on them, it was done on this oversized version, and if you then let InDesign resample them, you will end up with something not quite as good as if you had made the image exactly the right size and sharpened it.

Now, this is a rotten deal. For one thing, it pretty much means that you can’t put oversize images into the files so that viewers can zoom in to see more detail. It means that when 300 dpi screens are commonplace (next August, say) you’ll need to redo your PDF portfolios and books. And it means that if you embed 100dpi sharpened images in the online version, you can’t use the same image files for your Blurb print version.

Rotten all around. I’d observe one little out, which is that approximately zero people will view your PDF file at whatever the heck their PDF viewer calls ‘life size’ – basically pixel per pixel. So that viewer is going to resample whatever you put in your PDF file anyway. This is rotten, because no matter what, your images are not sharpened at whatever resolution the PDF viewer is displaying them at. Rotten, rotten. On the other hand, if you know that the viewer is going to display your images without sharpening, perhaps the right thing to do is embed oversized sharpened versions, so that when people zoom in all the way, they get some positive impression of your work.

Until we resolve this little conundrum with better control over how images are displayed in PDFs, I see no way out of this box. Yes, it’s rotten. Rotten is the word of the day.

7 Responses

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  1. Gordon McGregor said, on September 1, 2009 at 7:40 am

    when I’m working with inDesign, I bring the images in finished. Sized, sharpened, everything for whatever size of PDF I’m planning on putting together.

    I’m weird enough to actually view PDFs at 100%, too.

    I might have to go and trawl all the inDesign books on Safari and see what they recommend.

  2. Gordon McGregor said, on September 1, 2009 at 7:50 am

    This may offer some insight : http://www.adobe.com/products/postscript/pdfs/highresolution.pdf

    All my executive summary is : you are screwed. In much the ways described above.

    ZIP compression is going to be lossless, so always safe to use. I’d tend to get images right before placing them in inDesign. Even to the level of standardising file type, colorspace etc. You can certainly convert them in inDesign, but you’ll have to exercise the usual caution to ensure you convert them correctly – just easier to do it all up front.

    When I produced a web and print SoFoBoMo PDF, I did two completely separate versions in inDesign. Different images, different cover layout, different page layout to a certain degree. Web is a different medium to printed book, to do both well requires attention.

    If you are really doing it right, font sizes should change – as for example, 12 pt is great on a screen and terrible on a page. Similarly, fot choices should probably change – witness the whole IKEA gnashing of teeth over their use of a web/ display font for their new logos.

    Certainly all of these things can be glossed over or described as being overly fastidious, but then, you might as well just slap in any old pictures, too.

  3. Bryan Willman said, on September 1, 2009 at 8:55 pm

    You are screwed, but maybe not by what you think (or at least not mostly.)

    When a book is printed, it is known what size it will be. What the resoultion and color depth will be. It will be known or at least hoped that the image will start clean. It will not normally be disturbed by popups offering to introduce you to the cheap date of your dreams.

    When a set of images is online, what you really know is that the set of images is online. And as time goes on, the problem gets worse. It is already the case that mobile phones can show .pdfs, and one imagines that will be practical soon. On the other hand, my cinema monitor with 2560×1600 and about 100dpi resolution will eventually be surpassed. If you optimize for the cell phone, I’ll have a really hard time with your image.

    So the best bet, I think, is to size images for a pretty big monitor, and hope that downsampling does more good than harm. I think this is much safer than sizing for a small monitor and playing roulette with upsizing.

  4. Anita Jesse said, on September 2, 2009 at 1:33 pm

    While your early posts on this topic filled me with enthusiasm (especially your test version), the last two entries (along with comments) certainly brought me face to face with cold, hard (dare I say rotten) reality. A venture worth tackling, but not one with easy solutions.

  5. Peter Szawlowski said, on September 2, 2009 at 7:11 pm

    To add a bit more to an already complex issue – The current release of Acrobat (9 PRO) allows you to assemble text, graphics, Powerpoint files, photographs, CAD files, video, and audio files into what Adobe calls a portfolio which then anyone can view with the Acrobat Reader, so your concept of a “Book” might perhaps evolve into something else.

  6. Gordon McGregor said, on September 2, 2009 at 10:21 pm

    the thing probably to not lose sight of is that while this might not be a perfect presentation format, it is the presentation format that has the most promise.

    You could I suppose code a more intelligent website that presented images and modified them on the fly, to suit the current viewer, but that’s maybe more work and might lead you to a flash website (and we know how Paul feels about them)

    So you could spend much time gnashing and fretting over the failings of PDFs. Or we could use them to the best of their capability and let many more people see our pictures than currently and in a more controlled but still accessible format. Choices, choices. If only there was a looming 1 month deadline to move things along.

  7. Gordon McGregor said, on September 2, 2009 at 10:22 pm

    and as a follow-on to that, if you are worried about sharpening and resizing, we haven’t even talked about monitor calibration and the hideous places many pictures will be viewed. C’est la vie.


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