PDF usability and best practices?

[Wilhelmina Randtke]

I know that overall file size is key to whether people will be able to
easily download and open a pdf...

... but, *Are there any guidelines or recommendations about document size
for pdfs?*


My concerns are:
The access copy has to be the preservation copy, because it's highly
unlikely someone will think to preserve it.  So, for scanned images, most
of the flexibility in reducing file size will come from reducing resolution
and so permanently loosing some of the representation of the original paper
object.  Nevertheless, a larger file size will result in access issues -
longer downloads, higher chance of an error during the download process,
clunkier handling of the pdf using any viewer.
For a representation of a voluminous document, the tradeoff is that having
multiple open documents is confusing, but also having a single 5000 page
document open is confusing.

I would like to know whether anyone knows of studies on this tradeoff
between image quality and file size.  I would also like examples of ways of
presenting a very long text by breaking that text into segments - how are
the segments arranged to allow meaningful retrieval of the desired part of
the text, and how can the pdfs be presented in ways that aid navigating
across the entire text?

-Wilhelmina


On Fri, Mar 16, 2012 at 7:58 AM, Bob Rasmussen <ras at anzio.com> wrote:

> This is a partial answer, based on what I know of PDFs' internal
> structures.
>
> A key consideration is whether the PDF is "linearized". If it is, then the
> browser does not need to download the entire PDF before some of it (the
> first page) can be viewed.
>
> Other factors to consider:
>
> * Overall file size (as mentioned by someone else)
> * Number and type of embedded fonts
> * Whether it's "searchable". When pages of text are scanned, each is an
> image. When it has had OCR done on it, it becomes searchable (and could
> also be read aloud by screen reader software).
>
> On Thu, 15 Mar 2012, Wilhelmina Randtke wrote:
>
> > I am looking for recommendations or guidelines on best practices for
> > displaying PDFs on the internet.
> >
> > What I don't want:  I am not looking for ADA compliance.  I am able to
> find
> > that.
> >
> > What I do want:  I am looking for anything about ability to access the
> > document - so:
> >   -  How large a file size is acceptable?  (I anticipate U.S. visitors to
> > the project this is for.)
> >   -  How long in pages a document can be before it becomes overwhelming
> to
> > a reader?
> >   -  Any size constraints imposed by different PDF viewing devices and
> > connection speeds?
> >   -  Ways to represent a really long document - like a novel - and
> > represent it in meaningful ways in PDF format, without doing a single
> giant
> > PDF (and without becoming married to technology other than PDF-A and
> html)?
> >
> > Any pointers to guidelines or best practices on displaying voluminous
> PDFs
> > would be appreciated.
> >
> > -Wilhelmina Randtke
> >
> > ============================
> >
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> >
> > 2012-03-15
> >
>
> Regards,
> ....Bob Rasmussen,   President,   Rasmussen Software, Inc.
>
> personal e-mail: ras at anzio.com
>  company e-mail: rsi at anzio.com
>          voice: (US) 503-624-0360 (9:00-6:00 Pacific Time)
>            fax: (US) 503-624-0760
>            web: http://www.anzio.com
>  street address: Rasmussen Software, Inc.
>                 10240 SW Nimbus, Suite L9
>                 Portland, OR  97223  USA
>
> ============================
>
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>
> Web4Lib Web Site: http://web4lib.org/
>
> 2012-03-16
>

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