Oliver Heins schrieb:
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 the visible 'knockedout' text on the picture is just another acrobat bug. I manually checked the text and the OVP attributes are correctly set. If you use the coloring mechanism (Ausgabenvorschau -> Farbwarnungen -> [x] Überdruck anzeigen), you will see that everything looks ok.
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.
I noticed this too (no picture with mkiv). BOF = Bug Or Feature :)
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