Hello Paul et al,
As Olaf mentioned already the English documentation will be available
soon. It describes exactly how to calculate the CMY values based on
the CIELAB values of the respective black ink patch taken from the
characterization data (absolute colorimetric color conversion).
With regard to your question about the selected black ink percentages:
We wanted to add a quarter tone and a three quarter tone to the 50%
patch. 40 percent sits too close to 50 and 80 is too high.
Of course it would have been possible to add further patches with
percentages between 0 and 100 %. But as all of us know space is very
limited and paper cost is another reason to limit the strip length.
The versions 'L' and 'M' contain patches to capture the dot gain
curves plus trapping. The strips shall not exceed the width ('M') and
height ('L') of A4 pages, letter respectively. Otherwise it would not
be possible to place the strips on typical press sheet signatures. In
order to enable effective measurements by spectrophotometers such as
the Heidelberg ImageControl the patches have to be not smaller than 6
by 5.5 millimeters.
Best regards,
Florian
Am 23.12.2005 um 07:44 schrieb Marttila Jouni:
Hello Paul
It shouldn't be too difficult to make also 40% and 80% patches. I have
myself made it so that I created 3-colour profiles from Fogra data,
looked
what Lab e.g. 40 black gives and then look from the 3-colour
profile what
CMY values this Lab-values of black correspond.
And actually Eci/bvdm CMY 50% correspond to 45/36/33 for ISOcoated.
If we
would force cyan to stay 50% we would end up with something like
C50%, M42%,
Y37%, which would correspond to K56%
I have already tested Eci/bvdm gray control strip and our own with
same
principle on test printing and it works very well.
BR Jouni Marttila
-----Original Message-----
From: eci-en-admin(a)lists.transmedia.de
[mailto:eci-en-admin@lists.transmedia.de] On Behalf Of Paul Sherfield
Sent: 22. joulukuuta 2005 19:50
To: eci-en(a)lists.transmedia.de
Subject: [ECI-EN] Re: ECI/bvbm Grey Control Strip (M) Fogra 27
Hi
Is there ant English documentation on the use of this control strip?
Also can I ask why the 50%, and 70% patches were chosen over
the 40% (quoted as 50% 40% 40%) and 80% which are highlighted
in the Altona documentation?
And where can this chart be downloaded?
Many thanks
Paul Sherfield
The Missing Horse Consultancy Ltd
Telephone: 01442 871752
Mobile: 07899 906385
http://www.missinghorsecons.co.uk
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