RE: show a PDF pop-up based on the viewer's zoom value ?

Subject: RE: show a PDF pop-up based on the viewer's zoom value ?
From: Amy Dohlman <amdohlman -at- uwalumni -dot- com>
To: monique -dot- semp -at- earthlink -dot- net, techwr-l -at- lists -dot- techwr-l -dot- com
Date: Tue, 9 Mar 2010 08:23:06 -0600

Monique says:

> And I've seen this problem (images in PDFs appear fuzzy at some zoom values
> but not others) with images created all in vector formats by a variety of
> tools (Illustrator, Visio, etc.).  Isn't this just a PDF viewing issue?

Monique, I believe you're right, it is a PDF viewing issue. A few years ago,
I spent more time than I like to think about chasing down a PDF fuzzy image
issue. Like yours, my images printed crystal clear, but on-screen they looked
fuzzy or distorted.

My research led me to believe that if I could find the exact magnification to
use in the PDF, then voila - crystal clear images both on-screen and in print.
That magnification depended on the dpi used when I imported the images into
Frame - for a dpi of 150 (which was what I commonly used) it was something like
133%. (Always a weird value, like 127% or 154%, never something to the nearest
5%.) However, our manuals (and PDFs) were laid out such that once you zoomed
into the graphic to see it "crystal clear," then you were too close to
read the text without scrolling and such.

I've also noticed wierd artifacts or display issues with other elements in
PDFs. For example, we use ruled lines under headings or in the footer at the
bottom of the page, and in our tables. When you open the PDF, some of these
rules display as thicker or thinner than they should be (or sometimes disappear
entirely on screen). Yet when you print, they print perfectly, exactly as they
should. I just chalk these weird display issues and fuzzy graphics up to quirks
in Adobe Acrobat (which is what I use to open and work with PDFs - another
software package might not have these issues).

You can set up your PDFs such that they automatically open at a specific
magnification – in Acrobat, select Properties from the File menu, then select
the value to use from the Magnification list on the Initial View tab. This
doesn't solve your issue, obviously, but it might give an indication of the
magnification to use to your viewers. You can also try saving your flowchart
in a vector format (such as EPS or SVG) if available in your program, then
import that – it may come through more clearly than the raster graphic.

Good luck!

Amy Dohlman

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