Re: convert gray vector PS into K channel in Photoshop?
Re: convert gray vector PS into K channel in Photoshop?
- Subject: Re: convert gray vector PS into K channel in Photoshop?
- From: Stephen Marsh <email@hidden>
- Date: Tue, 27 Nov 2001 22:45:56 +1100
Johannes writes:
>
How can I get Photoshop to convert PostScript with
>
"setgray" color definitions into the K channel of the
>
rasterized picture?
Johanne, I get the feeling you know more about the nuts and bolts behind
all this than me - I am into pre press, but here goes...
Best option:
Print off separated CMYK PostScript instead of composite...one file for
each separation.
This could be as .ps, .eps or .pdf for delivery to Photoshop.
Rasterize into separate greyscale mode images, flatten, then use the
merge channels command (channels palette options menu) to combine the
separate seps into one CMYK file - thus preserving the intended colour
from the original application. Combine any spot colours into spot
channels if required (the knockouts and overprints should be handled by
the source application producing the PS code).
>
I found this when I tried to convert a PostScript file with
>
some pictures and a test wedge in vector format into CMYK,
>
because the "proofer" would not take PostScript but TIFF.
>
The C, M, Y patches came out ok. But the K patches were
>
horribly brownish...
If you are after a conversion from composite data - then the high use of
black (max GCR or 0% start point for black) in UCR or GCR is requied to
separate the incoming data into the black channel.
As to your black printing brownish...
Do you mean this patch is K only, or CMY or CMYK?
Are you converting incoming composite CMYK PostScript to your CMYK
workspace profile, or is the CMYK being rasterized using the internal PS
code CMYK values...which are not converted, but a proifle assigned?
It sounds like you are doing some RIPing of PS data for desktop output -
so you might find this link of use:
http://www.macintouch.com/postscriptalt.html
Hope this helps,
Stephen Marsh.