RE: Qualifying a CMYK Press Profile
RE: Qualifying a CMYK Press Profile
- Subject: RE: Qualifying a CMYK Press Profile
- From: "Darrian Young" <email@hidden>
- Date: Mon, 25 Nov 2002 20:49:08 +0100
Graeme Gill wrote:
>
We've seen some weirdness on pigment based printers operating in their
>
"fake high resolution" modes, where they increase the pixel
>
addressability without a corresponding reduction in dot size,
>
leading to 200%+ ink coverage from a single channel, but it
>
generally isn't useful to keep pouring ink on once you've
>
got 100% coverage.
Can you explain what you mean by 200% ink converage? Do you mean double the
density of of the 100% patch? For example, 100% has a density of 1.8, and
another patch has a density of 3.6? I have never heard of a 200% dot and
usually % refers to dot.
>
Since the purpose of calibration is to put a printer back in a known
>
operating mode, it doesn't matter whether the density reading
>
corresponds to visual results or not.
Maybe, but if the software is using the density readings to adjust your dot
gain curves, it will cause a problem. Your density is gong up, but if the
software thinks it is going down, it adjusts them in the wrong direction.
>
> What has happened is that there
>
> is a color shift with this amount of density so the density meter does
not
>
> read the values correctly.
>
I doubt such an explanation. The whole point about density measurements
>
is that they are tuned for process control, and are deliberately chosen
>
to be narrow band to reduce sensitivity to the behaviour of the
>
colorant at the edge of its block band. Wideband measurements
>
(such as used for colorimetry) are going to be more sensitive to
>
color shifts (as they should be).
If then, visually it is evident that there is more density, but the density
meter says there is less, and the Spectroeye (which can do density readings
of spot colors also says it is going up), what is your explanation?
Regards.
Darrian Young
MGV
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