Re: dot gain and generic CMYK profiles
Re: dot gain and generic CMYK profiles
- Subject: Re: dot gain and generic CMYK profiles
- From: Maarten van der Spek <email@hidden>
- Date: Thu, 10 Oct 2002 21:17:30 +0200
Hi Neil,
Thanks for your responds.
>
> From Linocolor support I'll get information about the 'Offset-Euro-postive
>
> plates' profiles. All these profiles are for coated paper and the dot gain
>
> compensation is 18% (their no profiles for uncoated paper included by
>
> Linocolor Elite).
>
The profiles for GCR300 K85 would be acceptable for sheetfed pos non glossy
>
papers. IF it was too heavy there would still be room to cut back on the
>
press, yet the images separated from three color to this profile will print
>
correctly (except of course on high ratio recycle wood papers!).
>
The supplied Linocolor profiles are usable in most cases where a default sep
>
is needed, and you will only be able to out guess the worst scenario.
>
Playing with profiles in Linocolor or Photoshop will give you readouts in
>
the sample points the advantage goes to Photoshop as it's control over
>
rendering, Adobe CMM+ACE. Yet if you are feeding batch scans to a server
>
then you'll be running the separations through Linocolor.
The profile from Linocolor Elite for uncoated paper you recommended is this
named 'Offset Euro pos U300 GCR85' (max black 90)?
>
> Adobe's support tells me that the dot gain compensation in the Euroscale
>
> Coated 2 profile is 9% and in the Euroscale Uncoated 2 profile is 15% (the
>
> same values as standard shown in the Custom CMYK dialog box from Photoshop).
>
These are the numbers if you used a custom set ink set up. The profiles that
>
Mr. Knoll made take care of dot gain for each channel from specific measured
>
data sets. They are of a very good quality, the results are what one could
>
expect of high quality seps, hands down.
>
The other numbers when using custom set ups are confusing. Bruce explains
>
why in his book if I remember correctly.
Is your conclusion that the information from Adobe isn't right and that the
dot gain compensation for the Euroscale 2 profiles for Coated paper is about
19% and for uncoated paper is about 25%.
I cant find a good explanation in the book wy their is such a big difference
between the Photoshop's Custom CMYK standard settings and the Euroscale 2
profiles. The only two things I find in the book are that the way dot gain
compensation is calculated is changed (but in what way?) and that the old
and the new ink definitions for coated and uncoated paper aren't the shame.
>
> In the book 'Real World Photoshop 6' from david Blatner and Bruce Fraser I
>
> read that the dot gain for Euroscale Coated is about 19% an for Euroscale
>
> Uncoated is about 25% (table 5.1) and that the guideline for positive plates
>
> is 10-12% (table 5.2).
>
This is around average. The numbers go way down on CTP though. This is still
>
the big question for service bureaux , if they compensate with profiles
>
before the CTP plate setter or just run reverse transfer curves in the plate
>
setter.
>
>
Neil Snape email@hidden http://mapage.noos.fr/nsnape
>
Are their generic CMYK profiles for CTP, till now I'll always used Adobe's
Euroscale Coated 2 profile for it.
Best regards,
Maarten van der Spek.
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