Datacolor User to User Support Group.

In a message dated 2/13/08 4:38:24 PM, yahoo@... writes:


> So, question number one: Can I use a Spyder to produce a
> Photoshop-friendly profile without touching the graphics card
> LUTs? Gretag described this as an "advanced feature" when I
> last spoke to them, but it seems a logically obvious thing to
> want to do (use a colour-managed application with an LCD? how
> dare I...)
> 
You seem to want to get under the hood and soup up your car before you even 
try driving it. Making LUT-less profiles is NOT standard fare, not even a very 
good idea, and certainly NOT what you should be doing first,   though for some 
reason it seems to you like the obvious thing to do. The color ramps of an 
LCD are not nice smooth gamma shaped curves like those on a CRT; they need some 
pretty significant LUT adjustments to neutralize and match them channel to 
channel. Not doing that, and asking Photoshop to fix it all for you on the fly, 
to that very nonlinear, misbalanced screen is just not reasonable. Thats why 
neither of the major monitor calibration companies are recommending it to you.

> 
> Secondly, as mentioned, I used two monitors, with different
> gamuts. 
> 
Not only that, you use two different TYPES of monitors, which require rather 
different viewing conditions, and which should not be used side by side, or 
frankly even in the same room. You also describe one of them as nasty... you 
should get the best displays you can afford, and work from there, rather than 
work with nasty stuff...

> This leads me to two scenarios:
> 
> a) The file I'm processing is fully contained within the smaller
> gamut of the LCD. In this case, it would be useful for the CRT
> and the LCD to match (i.e. the CRT should, as much as possible
> for in-channel mapping, be calibrated using the graphics card
> LUTs - because I don't want to keep fiddling with it manually -
> to match the LCD, and I should be able to use the profile from
> the LCD). Or...
> 
> b) The file I'm processing needs the expanded gamut of the CRT,
> and I should use the CRT's profile with it calibrated to use
> as large a gamut as possible (which at least means that the
> limits of the RGB LUTs should be at full range, no matter what
> this says for the intervening values and the native white point).
> It would be nice to be able to apply some profile which would
> keep the LCD correct except for the clipped colours, but I
> appreciate that XP's CMS doesn't support doing that, so under
> these circumstances I'm going to have to accept that the LCD
> won't be "right".
> 
You are working way too hard at this. Just profile both displays (with LUT 
corrections, please) and if you don't quite trust the most saturated colors on 
one, then use Photoshop's Gamut Limit tool to check which colors in it are out 
of gamut... you won't need to do this often to figure out what colors are not 
going to be quite as satuated as they should be on that screen. And don't 
assume (until you do a 3d gamut comparison) that the LCD is notably smaller than 
the CRT, it may not be that much different, in fact it may be larger in some 
areas.
> 
> I'm assuming that I'd have to switch between the scenarios
> manually - I'm not expecting a Photoshop plug-in to automate
> the process!
> 
> You don't need to switch between anything, just use your display profiles for 
each display. The two will match, where they can match, and top out where 
they top out. There is no manual switching or manipulation needed. But you will 
need to use appropriate ambient light for both, and appropriate white lumiance 
for each. You won't get a side by side match unless you set both to the same 
white luminance, and have reasonably similar black points (thus dynamic ranges) 
on each, and thats not likely to happen with one LCD and one CRT.

C. David Tobie
WW Product Technology Manager
Digital Imaging & Home Theater
Datacolor Inc.
CDTobie@...
www.datacolor.com/spyder3


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