Re: linearization - luminance, chroma or density?
Re: linearization - luminance, chroma or density?
- Subject: Re: linearization - luminance, chroma or density?
- From: Mike Strickler <email@hidden>
- Date: Tue, 23 Jan 2007 14:10:25 -0800
1) Hue Hooks: Most inkjet inks will experience a hue hook at higher
ink
lay down levels. It's not uncommon to see 20 degrees of hue shift
from
70% to 100%. ICC profiles perform much better in environments where
there's little hue shifting. Quite often, the last 20-40 percent
of ink
will increase density and look darker to your eye but will actually
have
minimal or an adverse effect on chroma/saturation, the parameter
you're
really trying to maximize. As others have commented, the key is to get
the maximum saturation with the least amount of ink and then have the
profile add K to achieve darker colors.
Not necessarily. If the object is proofing, the objective is to limit
the inks so as to just encompass the gamut of the simulated output.
In the case of 4-color offset the limits may be set far below the
point where significant hue shifts occur. This may partially explain
why for 4-color press proofing purposes density linearizations seem
to perform about as well other types. Obviously the situation shifts
when proofing presses with extra channels.
3) Total Ink Limit: Most RIPs perform best if you're not overly
aggressive with the Total Ink Limit (TIL). I get nervous when I
need to
drop TIL below 200. Appropriate per-channel limiting helps keep
TIL in
the desired range.
Usually does, especially when printing on coated papers. Notable
exceptions are uncoated papers and textiles, in which case the TIL is
extremely low while per channel limits must be kept high enough to
achieve acceptable saturation.
Incidentally, the tools we've used to perform this kind of analysis
are
X-Rite's Colorport (for generating the CMYKRGB patches, free download)
and Colorshop X (I'm sure Colorthink could do the graphing, too).
In this regard I like the ink limiting in EFI/Best Colorproof, which
shows the resulting gamut of the proofer as compared with the
simulated device and even let's the user slightly enlarge or reduce
the proofer's gamut.
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