[argyllcms] Re: Aw: Re: IT8 target
- From: Graeme Gill <graeme@xxxxxxxxxxxxx>
- To: argyllcms@xxxxxxxxxxxxx
- Date: Wed, 21 Sep 2016 11:20:53 +1000
Lars-Daniel Weber wrote:
My problem is are the LAB values. I don't have access to the ISO file, it's
Of course, I could use Wolff's data (the measured ones) for this as
reference, but I don't
want to steal his work.
I think you will find that his aim values are based on the aim points of other
of IT8 charts, and are based on the ISO 12641 standard, which is in turn based
the Kodak Q60 values. The Kodak target values are given in their TECHINFO.pdf
available from their ftp site ftp.kodak.com/gastds/Q60DATA/TECHINFO.pdf
I've got a high quality photoprinting service, which uses the same machine and
paper as Wolff does. So I just want to give it a try and play around ;)
I'm not sure "playing around" and avoiding spending money add up to the same
thing though - typically there is a lot of work in getting these things right.
For instance, to make a chart that has similar patch values, you first need to
create a profile for your photoprinting service, and that means printing a few
thousand test patches and measuring them. Then you would create a trial IT8,
measure it and then correct the patch values.
And photoprinting services are notoriously poor subjects for profiling, because
1) they often have automatic, image dependent adjustments going on (to make
customers pictures "look good"), and
2) often don't have much clue as to what color management is all about or what
their machinery is actually doing in this regard. All too typically they
will be in an sRGB "emulation" mode when you send them a file, and won't
have any repeatable (i.e. non-manual) means of printing a file with native
photo processing gamut. etc.
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