Re: Canned Epson Profiles and black point + linear GCR
Re: Canned Epson Profiles and black point + linear GCR
- Subject: Re: Canned Epson Profiles and black point + linear GCR
- From: email@hidden
- Date: Tue, 27 Jul 2004 11:14:20 EDT
In a message dated 7/26/04 11:29:36 PM, email@hidden writes:
>
Now, the only thing remaining, it seems, is some guidelines for when one
>
type of separation style is better than the other.
>
With inkjets this often has more to do with the inks than the images; for dye
inks, Epson traditionally used a very skeletal black, with a dark gray
seperating almost entirely to CM&Y, while a full black seperated to K, in order to
make black ink only text, since there are no PostScript smarts to determine
vector from raster elements. With the release of encapsulated pigment inks, Epson
found it necessary to run black (and more recently light black, otherwise
known as gray) ink way down into the light areas, and way out into the color
mixes to minimize the yellow component, which was causing objectionable levels of
display lighting dependend color variation (in slang: metamerism).
This is clearly demonstrated by the Epson 2000p, whose early driver suffered
from wildly variable colors, while the rewritten driver suffered, instead,
from coarse black dots. Later pigment printers had smaller dot sizes and/or gray
ink to reduce this graininess.
The logic used for black and white printing with contemporary RIPs is based
on a more extreme, but more limited version of this UCR/GCR concept: remove
all yellow from the mix, as its the yellow ink that causes the variation. Since
the neutrals are a bit warm already most near neutral tones can be reached
without any yellow, and the resulting prints will show little variability under
different viewing light colors.
C. David Tobie
Product Technology Manager
ColorVision Inc.
email@hidden
www.colorvision.com
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