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Re: !Who benefits of PDF tags aside from screenreaderusers?


From: Chagnon | PubCom
Date: Aug 29, 2013 8:49PM

Duff described some PDF readers/viewers that can change the visual
appearance of the PDF, but that type of viewer is not commonly used by the
general public.

The majority of PDFs are viewed as is. In fact, the main reason why
publishers, graphic designers, government agencies, and business use PDFs is
to "lock down" the document so that it deliberately can't be changed. PDFs
generally aren't edited or allowed to have the fonts, font sizes, white
space, and the basic appearance changed at all.

However, Adobe and other software companies do make tools that allow the PDF
to be altered, somewhat, and I expect we'll have more in the future.

The difference between an HTML webpage and a PDF of the same content is
mainly the visual appearance. Websites have the main body text run from the
top of the page to the end, continuously and linearly, and the story's H1
heading is usually at the very top of the page where it is read first.
Compared to print design, there's little control the designer has over how
the webpage will render or appear in everyone's browser. On a webpage, fonts
will adjust, sizes adjust, the layout can flip things from here to there,
especially with the current trend called "responsive design" that redesigns
the page depending upon whether it is viewed on a large monitor or mobile
device or tablet or whatever.

It's called "fluid" design or "responsive design" but as a graphic designer,
I call it pure chaos! Web design is 180 degrees opposite of how that same
content will appear in a 2-page spread of a highly-designed magazine.

When I art-directed commercial magazines and marketing materials, it was my
job to make the design as visually rich as possible: lots of graphics,
colors, unusual layouts, call-out boxes, wild typefaces...designers train
for years how to produce these designs with their software tools because
they win readers and increase sales for the people who hire them. For
example, one of my favorite designs had the 4" tall headline stacked at the
bottom edge of the page and running across both pages in the spread. The
bottom edges were clipped off leaving only partial letters. A custom
illustration was drawn that intertwined around the headline's individual
letters, snaking in and out and over and around them. The main body text
started on the right-hand spread, on the second page not the first. It used
very distinctive typefaces and overlapped part of the illustration and
headline. The first letter of the body text was a "drop cap" which portrayed
that letter in a visually eye-catching way (the industry has stats that show
drop caps increase readership by 10% ... sighted readers, that is). The left
page, the first page of the spread, was mainly blank with a "deck head"
which is 1 or 2 short sentences that lead the reader from the title into the
body text. Deck heads are meant to be visually sexy, attracting the reader's
eye and piquing his interest (and they increase readership by 15%).

This magazine article was a work of art that took 3 of us several days to
design, craft, and produce. It was one of the most heavily-read articles
that year so the publisher was very happy with the results. And it won us a
national design award, which made us very happy.

The last thing I, as a designer, would want to see is our handiwork hacked
to pieces and turned into a visually boring webpage (oh please, no!). Hence,
graphic designers make PDFs of their work so that it is locked down and
can't be changed. The PDF is an exact replica of the original design...each
letter, each pixel of white space, each dotted i and crossed t, and the
visual effect of the entire 2-page spread are preserved in a PDF.

Consequently, this type of PDF is an accessibility nightmare!

Not only does it have to be tagged with <h1>, <P>, etc., but the designer
also has to sequence the tags in a logical reading order so that the
headline across the bottom of the 2-page spread is read first, then the deck
head, and then the body text - which is very different from the visual
reading order of the design.

Summary, that's how PDFs are used in the publishing and graphic design

Government agencies use them to lock down a report's data, or to make a PDF
version of a printed form. Tax forms have exacting visual design
requirements because they must be readable by scanners that expect each data
field to appear in a particular location on the page..

The business world uses them for similar purposes, and also for marketing
and advertising materials which are visually oriented like the magazine

I don't know of any mobile browser that renders a PDF differently than a
desktop browser. The only difference is that the magazine spread I described
above would be reduced to postage-stamp size on a mobile browser. Still
there and intact, but ridiculously tiny.

-Bevi Chagnon
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-----Original Message-----
[mailto: <EMAIL REMOVED> ] On Behalf Of Duff Johnson
Sent: Thursday, August 29, 2013 5:15 PM
To: WebAIM Discussion List
Subject: Re: [WebAIM] Who benefits of PDF tags aside from screen reader

> Do tags affect how the PDF is displayed visually in a browser?

Implementers of PDF viewers may use tags in any number of ways, including to
influence visual display, drive navigation systems (such as zooming, or a
joystick), move between form-field elements and more.

Example: one could use tags to represent a three-column document in a single
column of text. Existing tools such as pdfGoHTML and VIP Reader provide
precisely this capability.

> If so, is there a difference between desktop browser and mobil browser?

Whether and how to use tagged PDF is a choice for each software developer.

To answer your specific question, I'm not aware of mobile browser software
that makes use of tagged PDF at this time (but I would love to be corrected
on this point!)

Duff Johnson

p +1.617.283.4226
w http://duff-johnson.com

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