Re: Postscript printer errors with rounded barlines?

[Jan Warchoł]

Hi Han-Wen

2011/7/19 Han-Wen Nienhuys <address@hidden>:
> Hi guys,
>
> I've noticed that some printer postscript interpreters add
> linethickness to barlines when printed, even though they create with
> draw_round_box with line thickness 0.0.  The result is that barlines
> noticeably stick out of the staff; the error is in the printer, since
> GV at 64x mag shows that everything is OK, and show with both the PDF
> and the PS output.  Unfortunately, a small example does not trigger,
> but the attached file when run through lilypond at commit
> 4e55f40a1bf65633fedc62d09d91d8e3c0247efe does (PDF attached).   By the
> amount it sticks out, I suspect it is somehow picking up the
> blotdiameter of another routine, but I have no idea how that could
> happen.
>
> I have seen this on my home printer (HP LJ 2100, with HPs postscript
> extension card, configured as generic postscript in CUPS) and the
> printer at my office, (Gestetner mp c2550).  This is a regression, as
> I am sure it worked correctly at some point on my printer before, but
> it I can't see anything obvious in the change log.

I'm not experienced with PostScript, but i have an impression that
this may be related to an issue discussed earlier - see here
http://lists.gnu.org/archive/html/lilypond-user/2007-07/msg00485.html
and here
http://lists.gnu.org/archive/html/lilypond-devel/2007-07/msg00072.html
I see that something about draw_round_box was said there...

If you look at top example from here
http://lists.gnu.org/archive/html/lilypond-devel/2007-07/msg00076.html,
it shows how Lily-made pdfs look also on my screen (some stems thicker
than others, barlines sticking below staff like in the attachment).
If i remember correctly, the problem mentioned there was dismissed as
being screen-specific and not visible in print.  However, i've
discovered that it is visible in print - it's simply less ugly because
printers have generally bigger resolutions that computer screens - but
it's still there.  I've made a scan of a printed Lilypond-made pdf.
The printer's resolution is 1200 dpi, the scanner's resolution is 2400
dpi.  The resulting image clearly shows sticking out barlines (it's
very interesting that they stick out below the staff - on the top they
are perfectly flush with staffline - just like in on-screen viewed
pdf); also varying thickness of stems is visible (compare first two
notes, or notes in the second measure). The file is here (watch out, a
big png): http://www.sendspace.com/file/hxx179
It's also interesting that stafflines have sharp edges, while stems
and barlines are blurry.

HTH...
Janek

barline bug.png
Description: PNG image