"Peter B. West" <[EMAIL PROTECTED]> wrote on 28.05.2004 01:15:26:

I suppose that everyone has noticed this exchange on fop-user.


Mike Kellstrand wrote:


I ran the PDF through Ghostscript and it looks like it is doing the


I did notice that the same PDF printed in Ghostscript vs. Adobe print out with slightly different size fonts. Arg! :)

Is there a specific reason for this pointer?

If there is any doubt: font sizes are the same whereever you print out a PDF
- as long as the PDF viewer application and the printer(driver) work correctly
and the user hasn't made any mistake.

Possible causes for this kind of problem:

1. The printer (or emulator) does not use exactly the same font, but a substitute
with differing metrics. GhostScript default fonts are not perfectly compatible
with the metrics of the Adobe base fonts - that goes at least for GhostScript
version from about a year ago.

2. This is a variation of 1. Improper setting of font match settings in the
printer driver options. Using device fonts in PCL printing is especially
dangerous as many drivers then don't handle Z-order or font color correctly in
addition to having device fonts with metrics that match only to 95% or so.

3. The user has made a mistake (page/paper scaling options if the Acrobat print
dialog, like fit to page, etc.).

4. The PostScript printer (or emulation) or the printer driver is buggy. The
Kyocera PS emulation is a little shaky in my experience - though not regarding
font sizes or metrics regarding the base fonts.

We have done lots and lots of PDF and PostScript output for a bunch customers
with an output of several 100.000 pages per month (by the way: more than 50%
of these still done with FOP) and using dozens of different printers, and a number of fonts (base fonts as well as others). Any font size or metric
problems during the last years regarding PDFs or PSes could be resolved to one
of the 4 reasons - most popular is 3.

Hope this resolves any doubt you might have.

Thanks Arnd. My argument is that the renderer must tell the layout engine about font metrics. I have always regarded PDF and PS (with obligatory fonts) as stable targets in this respect. It's reassuring to find that there are so many ways in which variations will creep in to the output of even such a heavily standardised format as PDF. To get the output point-perfect then, the renderer needs to know the peculiarities of the output device.

I'm not suggesting this, but I would expect these considerations to temper a little the enthusiasm for centralised font handling.

I thought my meaning more evident than it evidently was.

Peter B. West <http://www.powerup.com.au/~pbwest/resume.html>

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