Re: Dumb question - Printing Colorchecker
Re: Dumb question - Printing Colorchecker
- Subject: Re: Dumb question - Printing Colorchecker
- From: edmund ronald <email@hidden>
- Date: Thu, 27 Oct 2005 17:33:17 +0200
I took Steve Upton's suggestion, took Danny Pascale's LAB Colorchecker
file, updated it for my deviant red patch measurement and printed via
absolute colorimetric. I got a SUPERB print.
The only problem is the slight green tint in the neutrals when viewed
in sunlight (Epson 2100 metameric shift), and the red patch which
makes it almost but not quite.
This profile was generated with Monaco Profiler 4.8 and a DTP70, and
the least number of patches (half a sheet of A4).
Thanks to everyone on the list - in particular to Danny Pascale, Roger
Breton, and Steve Upton.
And I'm open to suggestions as to what books I should read - so I can
ask less dumb questions the next time round ;)
Edmund
On 10/27/05, email@hidden <email@hidden> wrote:
> Please note that Edmund's TIF file is encoded in Adobe RGB
> (D65), not L*a*b* (even though, as he mentioned, I checked
> the values in L*a*b* D50, as converted by Photoshop info).
> This may explain the apparent contradiction between what
> should be done and what is seen.
>
> To print this RGB D65 image would then require Rel. Col.,
> which corresponds to Edmund's neutral output.
>
> The blue tint when printing with Abs. Col. also
> corresponds to a D65 white printed relative to D50
> printing environment.
>
> Danny
>
> On Wed, 26 Oct 2005 22:48:40 -0700
> Steve Upton <email@hidden> wrote:
> > At 3:52 AM +0200 10/27/05, edmund ronald wrote:
> >>Roger, in the mean time, Danny Pascale has confirmed that
> >>my spectral
> >>values and LAB values match the colorchecker tiff aRGB
> >>file that I
> >>tried to print. Apart from one square (blue) which may be
> >>a
> >>manipulation mistake.
> >>
> >>Now how do I print this thing ? The colors look in-gamut
> >>when viewing
> >>the profile. Why do the neutral square go blue with abs
> >>col and stay
> >>neutral with rel col ? I don't get it ...
> >
> > The big difference is that Adobe RGB has a blue white
> >point so abs col reproduces the blue white point in the
> >output space. Lab has a D50 white point which doesn't.
> >
> > So, using Lab values with abs col is much more likely to
> >give you the results you want.
> >
> > Also, are you measuring or viewing to find the
> >difference? If viewing, make sure you don't have an odd
> >white surround casting everything.
> >
> > Regards,
> >
> > Steve
> >
> > ________________________________________________________________________
> > o Steve Upton CHROMiX
> > www.chromix.com
> > o (hueman) 866.CHROMiX
> > o email@hidden 206.985.6837
> > o ColorGear ColorThink ColorValet ColorSmarts
> > ProfileCentral
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