Re: PDF problems on multiple platforms

[Michael Richards <michaelr@xxxxxxxxxxxxxxxx>]

We use pdf extensively and I've had some 6 years experience of using it
intensively on Mac, NT and now Solaris.
In fact I even saw a demo of the beta of version 1 in 1990 (the beta was
called "Acrobat" and Adobe hadn't yet invented the name of the shipping
product -- true!)

The rest appears as glosses to your e-mail:

Thomas Michanek wrote:

> We need to convert our Frame documents to PDF so that they
> can be viewed in Acrobat Reader on both UNIX and Windows NT 4.
> We can distill to PDF on either platform.
>
> General problem: text and graphics appear different in Acrobat
> Reader on the two platforms. We need them to look as similar
> as possible, regardless on which platform the PDF is produced.
> What platform should we distill on and with which settings?
>
> *** We need advice from people with experience of PDF
> *** generating and viewing on both platforms.
> *** This request is rather urgent, since we need to show
> *** the advantages with multi-platform PDF viewing.
>
> OUR SETUP:
> FrameMaker version 5.5.3 on both platforms.
> Acrobat Distiller 3.02 on Windows NT 4.
> Printer driver: Distiller Assistant v3.01.
> Acrobat Distiller 3.01 on UNIX (Solaris).
> Acrobat Exchange/Reader 3.01 on both platforms.
> Distiller settings (identical on both platforms):
>   Compress text and line art, Downsample bitmap images on or off
>   (see below), Manual ZIP compression, Embed all fonts, Preserve
>   transfer functions, Unchanged color conversion, 3.0 compatibility
> Fonts used: Times, Helvetica, Courier (Type 1 versions)
> Graphics (imported screendumps) are monochrome, grayscale,
>   and color, at different dpi's (72, 100, 150, etc.)
> All documents viewed at 100% scale.

You omit here a most important fact: what is the graphics file format of
imported bitmaps?

> PROBLEM 1:
> The fonts Times and Courier appear identical on UNIX and Windows,
> but the font Helvetica appear different (without smooth).
> The Acrobat Online Guide says:
> "A font rasterizer is built into Windows, OS/2, and UNIX Acrobat
> viewers. Adobe Type Manager (ATM) is used to rasterize fonts on
> the Macintosh."
> Why then does Helvetica look different on UNIX and Windows?
> Note: we embed fonts, but are these fonts really embedded?

Good question. Normally what happens when a font is not included on
system or embedded is that either Acrobat or ATM look up a database of
known fonts (Adobe fonts as a general rule! Other foundries names are
not necessarily included in the database) and produces an approximation
of the font using either of two Multiple Master Fonts ("Serif" & "Sans
Serif"). The glyphs are the right sizes but don't necessarily look like
the font in question. Now, is the exact name of the "Helvetica" font you
use known to the UNIX database? I wish I knew how to check this. BTW you
can check if the font actually has been embedded by going to
File:Info:Fonts, which brings up a list of all fonts in the pdf file.

There is no difference between the appearance of a font if rendered by
ATM or the font rasteriser or the Display PostScript of Solaris and some
other flavours of UNIX. (Let's face it, they all are based on the same
fragments of code.)


> PROBLEM 2:
> When viewing a UNIX-generated PDF on Windows, the grayscales
> and colors are rendered differently compared to UNIX.
> The same is true for Windows-generated PDF viewed on UNIX.
> Some grayscales/colors become "dotty" or "patterned" in a
> way that doesn't happen on the other platform. This is
> difficult to explain in words, but very annoying on-screen.
> Is this difference in the Acrobat Readers a known and
> unavoidable problem?

Unavoidable. Sorry.

> PROBLEM 3:
> When downsampling graphics is turned off, the resulting PDF
> becomes much larger in Windows (as expected). However, on
> UNIX, the resulting PDF actually becomes *smaller* (with
> all other settings being identical in the Distiller).
> We have checked the resulting PDF by zooming in on graphics,
> and the graphics are really downsampled (or not) as expected,
> on both platforms. Can anyone explain this?

This is why I asked what your graphics file format is. And what is the
nature of the graphics. Bet that they are screen grabs, right? If so, a
couple of things are happening. 1) If you have the downsampling off, and
these screen grabs have large areas of flat colour (as screen grabs tend
to have). Distiller detects that the best way to treat these graphics is
to LZW compress them. Nice. Distiller has done this since version 2.1.

BUT, if you downsample, Distiller essentially takes four pixels and
renders them as one pixel. The image therefore gets fuzzy (i.e. is
"anti-aliased). That means that Distiller no longer detects the image to
be a screen grab and turns it into a jpeg. jpegs can only be greyscale
or 24-bit colour. The jpeg version will tend (for screen-grabby stuff)
to be bigger than the LZW version. The reverse is true for photographs,
but that's another story.

Lastly, I bet you're using tif or gif. Right? Both are indexed colour.
Acrobat doesn't use indexed colour. For some reason (Schlomo? do you
know?) UNIX will turn grey tifs into 8 bit images (greyscale) while
other Distillers (Mac, definitely, Windows too?) turn all tifs into
24-bit, resulting in file bloat.

> PROBLEM 4:
> With smoothing turned on, monochrome graphics at 72 dpi are
> not affected on UNIX, but they become "smoothed" in Windows.
> If you change the scale somewhat, the graphics are not
> "smoothed" anymore.
> Is this a known "feature" and how do you avoid it?

Yep, it does it on mine too! I suspect that the reason is the Display
PostScript used on my Sun to draw stuff to the screen. Anyone else?

> Other questions:
> Is the used printer driver in Windows a bad choice?
> How do we know what PPD is associated with the driver?
> Do we need exactly the same version of Distiller on both
> platforms? Is any version "better" than the other?

Never use the out-of-the-box PostScript driver from MS. They "improve"
on the drivers they get from Adobe! And always have, right back to the
early days of Windows 3.0 (when the driver was written by Aldus).

> Grateful for any advice,
>
> - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
> Thomas Michanek, Documentation Manager, Telelogic Tau
> Telelogic AB, Teknikringen 9, SE-58330 Linkoping, SWEDEN
> PHONE/FAX:  +46 (0)13 200656/212166
> EMAIL:  mailto:Thomas.Michanek@telelogic.com
> WWW 1:  http://www.telelogic.com
> WWW 2:  http://hem1.passagen.se/framers
> - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
>
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