Bug with overprinting in Mark II/IV?

From: Oliver Heins <olli@sopos.org>
To: mailing list for ConTeXt users <ntg-context@ntg.nl>
Subject: Bug with overprinting in Mark II/IV?
Date: Fri, 11 Dec 2009 13:53:04 +0100	[thread overview]
Message-ID: <874onxhdu7.fsf@sopos.org> (raw)

Hello,

with color black overprinting is not working.  You can easily spot this
when you use the »Ausgabevorschau« (sorry, my acrobat is in german
locale, must be something with »preview« in english; located in the
»tools« menu) in acrobat and remove magenta and black from the preview.
Whilst under the region with the magenta colored text the picture gets
shown, in the region with the black colored text the text is cut out of
the picture, leaving white.

I think this is a bug, as overprinting makes most sense with black.  It
happens both in Mark II and IV -- you have to manually copy the
hacker.jpg to your working directory (under linux e.g. with cp
$(kpsewhich hacker.jpg) /path/to/your/working/directory) and change the
path to make the minimal example work under mark iv.

Best regards,
 olli

\setupcolors[state=start,cmyk=yes,rgb=no]

\definelayer	[mybg]
		[x=0mm, y=0mm,
		width=\paperwidth, height=\paperheight,
                repeat=yes]
\setlayer	[mybg]
		[hoffset=5cm, voffset=7cm]
		{\externalfigure[sample/hacker.jpg][max]} % mark ii
%		{\externalfigure[hacker.jpg][max]} % mark iv
\setupbackgrounds[page][background=mybg]

\starttext

{\bf With foregroundcolor = magenta.}
\color[magenta]

\startoverprint
\input tufte
\stopoverprint

\color[black]
{\bf With foregroundcolor = black. \color[magenta](Some magenta
  without overprint)}
\color[black]

\startoverprint
\input tufte
\stopoverprint

\stoptext

-- 
Oliver Heins heins@sopos.org    http://oliverheins.net/
http://blog.overheins.net/     F27A BA8C 1CFB B905 65A8
http://scriptorium-adp.de/     2544 0F07 B675 9A00 D827
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Please avoid sending me Word or PowerPoint attachments:
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