Re: Ambient measurements with PM 4.1.5
Re: Ambient measurements with PM 4.1.5
- Subject: Re: Ambient measurements with PM 4.1.5
- From: Roger Breton <email@hidden>
- Date: Fri, 24 Oct 2003 21:53:11 -0400
In PMP, when choosing a White Point for calibrating the monitor, if the user
clicks on 'Set Paper White' up comes a dialog box where one is expected to
enter some XYZ values. My question is as follows: what values does the
program expect there?
A) D50/2 tristimulus values corresponding to the spectral reflectance of the
'substrate' one wants to calibrate his CRT to? Like, if I take my EyeOne and
take a measurement of the photographic paper onto which my images are
printed at my lab which I am using inside my viewing booth -- assuming that
this is what I am going to try to match on my CRT;
B) tristimulus values derived corresponding to the light source in my
viewing booth;
C) tristimulus values of the 'substrate' as measured with a
spectroradiometer -- thus integrating the spectral power distribution of the
light source inside the viewing booth, the spectral recflectance of the
'substrate' weighted by the 2 degree standard observer color matching
functions?
Further, I assume it is necessary to normalize the XYZ values so that Y =
100, always? If you select 6500K in the drop down list and then you press
the Set Paper White button PMP displays the normalized tristimulus values of
D65. I guess that's what the program is expecting.
Regards,
Roger Breton | Laval, Canada | email@hidden
http://pages.infinit.net/graxx
>
At 8:09 AM -0400 10/24/03, Roger Breton wrote:
>
> Hello Alex and Thomas,
>
>
>
> Can you give any details about the measurement geometry of the i1 in this
>
> mode? This is not Emissive mode but measuring light falling the head of the
>
> i1 as in trying to characterize the spectrum from a light source, right?
>
>
Technically it is not emissive mode as that is not including the diffusion.
>
>
When you use an ambient-capable Eye-One to take an ambient reading, you attach
>
a small black cap to the Eye-One that has a white diffusion chip in it. What
>
they are trying to achieve is the 0-degree geometry with a "perfect" diffuser
>
- that's written somewhere in a technical spec as the official method for
>
taking ambient light readings. (I'm sure someone else on the list can tell us
>
the spec)
>
>
> I
>
> assume you guys are refering to the i1 Photo. Do they say (Gretagmacbeth) in
>
> what radiometric units is the i1 measuring in this mode: microWatts / m2/sr?
>
>
Eye-One Photo or "better". This would include any of the other bundles the
>
Eye-One Spectro comes with such as Publish, Beamer and Pro (w/ ProfileMaker
>
4).
>
>
> Seriously thinking about upgrading my i1 to an i1 Photo. (or Publish?)
>
>
If you have a Display, Monitor or older Pro then you will need the upgrade.
>
>
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
>
________________________________________________________________________
_______________________________________________
colorsync-users mailing list | email@hidden
Help/Unsubscribe/Archives:
http://www.lists.apple.com/mailman/listinfo/colorsync-users
Do not post admin requests to the list. They will be ignored.