Re: MS Color Control Applet
Re: MS Color Control Applet
- Subject: Re: MS Color Control Applet
- From: Steve Upton <email@hidden>
- Date: Fri, 30 Jun 2006 22:59:51 -0700
At 6:14 PM -0700 6/30/06, Marco Ugolini wrote:
>In a message dated 6/30/06 5:41 PM, Steve Upton wrote:
>
>> - it turns out that any white point other than D50 in monitor profiles was not
>> intended in v2 profiles and has been "outlawed" in v4 profiles. All colors are
>> to be adapted to D50 and the white point should be D50 from now on.
>
>
>Hi Steve.
>
>Does that mean that we should only create D50 monitor profiles from now on?
If you are asking if all monitors should be calibrated to D50, no.
>Or that if we insist on making a monitor profile with a D65 white point, a
>program that follows v4 guidelines will do...what exactly?
That's the right question. The software will follow the ICC spec and adapt the white point to D50 before writing it into the profile. Any white point adapted to D50 becomes D50 (in monitor profiles) so the media white point tag in v4 profiles will always be D50 even if the monitor is calibrated to a different white point... and this is correct. It seems odd but it's OK.
> > - gamut comparisons should be done with the white points adapted in some
>> manner. This will give a better indication of how two gamuts compare that when
>> one of them has a shifted white point.
>
>Yes, makes sense. But there must be a difference between *adapting* the
>white point, on the one hand, and *scaling* it (and the black point too) on
>the other, with the possible absurd consequence that a newspaper output
>profile with its white and black points scaled would seem to have more or
>less the same gamut as a sheetfed coated profile, which is clearly
>ludicrous.
right but let's not confuse display profiles and print profiles. Displays' white points are, by definition, Lab=100,0,0 - the flavor of Lab depending on the calibrated white point. So a D65 100,0,0 Lab value adapted to D50 becomes 100,0,0 D50 (no change). BUT all the other colors get adapted too and that's the important part.
>Although it's what one gets by viewing these profiles in the
>ColorSync Utility, which scales all 3D profile graphs, from what I gather.
indeed. An interesting set of graphs but after close consideration I could not find a single graph in a typical CMYK profile that would mean anything to the average user.
> > With this is mind it makes more sense to map all monitor gamuts to 100,0,0
>> which is how ColorThink Pro now plots and non-pro ColorThink will follow as
>> well.
>
>Yes, that sounds right too. The objective is to represent a pure black and a
>pure white by means of an imperfect tool, i.e., a monitor display.
right.
> > At 9:16 AM -0700 6/27/06, Marco Ugolini wrote:
>>>
>>> When comparing color spaces on a 3D graph, I think the correct way is to use
>>> the absolute colorimetric rendering intent (which is the way ColorThink does
>>> it), that is to say, *not* to adapt the white point, and certainly not to
>>> perform any black point compensation.
>>
>> Ultimately what I decided to do was go with a hybrid approach. Because I
>> really wanted the measurement data cloud to match up with the gamut volume for
>> printers, I left print profiles graphing as absolute colorimetric by default.
>> ColorThink Pro will recognize display/workingspace profiles that have non-D50
>> white points and graph them as relative colorimetric.
>
>To a mere user like yours truly, it sounds like a fair approach.
>
>> Because Pro is, well, 'pro' level, I also left the ability to change this
>> behavior exposed to the user. So when a profile is graphed in Pro the default
>> intent will be "device gamut" which determines the appropriate intent based on
>> the above logic. You can also override this setting to graph D65 spaces
>> offset, or pull print gamuts' white points up to 100,0,0 and so forth.
>
>Now, I'm having a problem understanding that. How can it be considered
>appropriate, say, to bring up the white point of a newspaper output profile
>to the 100,0,0 peak and still think that this is a dependable representation
>of the gamut produced by that medium?
well, you could argue that it no longer represents the gamut. OR you could say that it represents the ICC Lab-range of the device values as they get mapped by the profile into the PCS using the relative colorimetric intent. (a mouthful for sure but we have users who are looking for this very thing)... ALSO it could be said that it DOES represent the gamut to the 'adapted eye'. In certain viewing conditions the paper white is the dominant white in the scene and so it represents 100,0,0 white.... probably not with newsprint though.
in other words there are several potentially valid ways of looking at it.
> > I hope this helps. Gamut graphing seems to be an area where there hasn't been
>> a lot of research and discussion so sometimes we're forging ahead into new
>> territory.
>
>Yes, and, speaking for myself, I thank you and others like you who dedicate
>so much of your considerable skills and mental firepower to the task, so
>that the rest of us can be a bit more sure-footed while meandering in the
>thick forests of color-land.
happy to help
>A happy 4th to you.
ch ......s..sssssssss..... BOOOOM!! hee hee hee....
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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