Re: PDF problems on multiple platforms

[Thomas Michanek <tmi@xxxxxxxxxxxx>]

On Thu, 12 Nov 1998, Michael Richards wrote:

> > Graphics (imported screendumps) are monochrome, grayscale,
> >   and color, at different dpi's (72, 100, 150, etc.)
>
> You omit here a most important fact: what is the graphics file format of
> imported bitmaps?

I didn't think this would matter, as the graphics are copied in and
stored within FrameMaker, but:
- monochrome screendumps are originally in XWD format
- grayscale and color screendumps are originally in GIF format

> > The fonts Times and Courier appear identical on UNIX and Windows,
> > but the font Helvetica appear different (without smooth).
> > Note: we embed fonts, but are these fonts really embedded?
>
> 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.

I didn't think the fonts would be embedded, since I've read somewhere
that Times/Helvetica/Courier are never embedded, but the font info
lists *all* fonts in the files. The lists are slightly different in
the Windows and UNIX versions of the PDF file, though.
This is, however, not a big issue.

> > 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.
> > Is this difference in the Acrobat Readers a known and
> > unavoidable problem?
> 
> Unavoidable. Sorry.

So you don't think that this problem is due to what Peter Spicer wrote:
 
> you have a BIG problem using version 3.01 of Acrobat Reader
> and Exchange. Version 3.01 has a well-documented problem with its
> graphics rendering engine that is the cause of much of the fuzzy 
> screenshot (raster graphic) problems people have been describing on 
> this list. This, of course, is assuming they have used the proper 
> Distiller Job Option settings for lossless compression . . .

But the problems are not with "fuzzy" screenshots, but a difference
in the "raster quality" of gray and colored areas.

> > 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).
> 
> 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.

But why does this then only happen on one of the platforms???
And we have specifically specified ZIP compression for all graphics.

> 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.

We don't use TIFF, so that cannot be the reason.

> > Is the used printer driver in Windows a bad choice?
> 
> Never use the out-of-the-box PostScript driver from MS.

We don't, we use the Distiller driver provided by Adobe.
But I guess we should be using AdopePS 5.0.1 instead?

Thanks and keep the advice coming,


- - - - - - - - - - - - - - - - - - - - - - - - - - - - -
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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