Re: How do one generate profiling patches (The hen or the egg)
Re: How do one generate profiling patches (The hen or the egg)
- Subject: Re: How do one generate profiling patches (The hen or the egg)
- From: Thomas Holm / Pixl <email@hidden>
- Date: Wed, 23 Apr 2003 12:42:12 +0200
email@hidden wrote:
>
You seem to be viewing this backwards; your print 100% Cyan, and read the
>
result as a Lab value. That tells you want value will result from that
>
recipe,
Yes essentially you get a lab (or spectral reading)
>
and also what values of Cyan will be out of gamut on that device.
How? The lab reading from the printed paper will only tell you the lightness
and a+b coordinates of the printed Cyan. You still need the reference value
to see how far off your reading is, and thus define the outer limit of the
gamut (how cyan can cyan be). Only when you know what is the maximum
printable cyan is can you define a gamut.
>
Then you derive an inverse table from all those values for the other side of
>
the profile. (Gross oversimplification).
I'd say, I still don't get it, I want to know the mechanics...
OK, maybe I didn't explain my point clearly enough:
Suppose I want to generate my own patches for whatever purpose (like Bill
Atkinsons TC 9.18 target for ProfileMaker). I'd build the CMYK (or RGB)
patch file with defined color values. Presumably I'd have to do this in CMYK
(or RGB for RGB profiles).
How do I generate a reference file for this new target? I need to be able to
build a profile for it...
If my understanding of profiling is correct (which it may or may not be) the
actual readings of a printed target are compared with a reference file. Thus
a gamut for the device is established, and at the same time the resulting
profile know what Lab coordinates the defined CMYK values will land on, and
have a basis for calculating the values falling between the defined patches.
What I don't get is the "double digital" target (CMYK and Lab that must have
a correlation) where you print one and compare the readings from this with
the other (lab reference).
It's the link between the two (CMYK or RGB patch file, and Lab reference
file) I don't get...
Best Regards
Thomas Holm / Pixl ApS
- Photographer & Colour Management Expert
- Adobe Certified Training Provider in Photoshop.
- Imacon Authorized Scanner Training Facility
- Remote Profiling Service (Output ICC profiles)
- Seminars speaker and tutor on CM and Digital Imaging etc.
- Home Page: www.pixl.dk 7 Email: th[AT]pixl.dk
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