Re: Black Generation
Re: Black Generation
- Subject: Re: Black Generation
- From: Henrik Holmegaard <email@hidden>
- Date: Mon, 12 Feb 2001 17:25:42 +0100
The problem is the black, which seems to print a very large dot for the
lighter shades. This becomes an issue when lighter colors are needed to be
proofed, and this output I have mentioned before on the digest as the 'dodgy
black stiple'.
...and this only seemed to reduce the Black Generation, not
remove it.
Should I be ... profiling in RGB ?
An inkjet has a larger elementary spot size than a press. Offset
printing is a contact sport, inkjet printing isn't. The jet of ink
travels a short distance and the spot is oversized to allow for error
in the placement. This is why the black spots are more visible in
inkjet prints.
When you do a proof, you do a CMYK-to-CMYK conversion via three
channel CIELab. This means that the original offset or newsprint
black is lost. It also means you get a black generation which is
optimized for your inkjet.
The relation between gamut volume, total area coverage and black
generation is roughly speaking like so: The goal is to get the pure
colors because they define the gamut volume which means keeping the
total area coverage up. Then substitute K for CMY in the shadows to
avoid soaking.
If you're using PrintOpen 4 for PC, there are presets for inkjet proofers.
I hope that this is not the only benefit of PrintOpen 4.0 (Black Generation
is a feature of the upgrade mentioned at their website),
PO4 just has other black generation algorithms than PO3. You can use
heavier GCR now, but you don't want to do that for profiling inkjets
as GCR replaces CMY with K in skintones, for instance.
--
Henrik Holmegaard
TechWrite, Denmark