Re: XYZ or Lab space for profile info?? (WAS: PhotoCal+Spyder exp erience)

[Steve Upton <upton@chromix.com>]

<x-flowed>At 2:51 PM +0100 8/30/01, Rew, Alan wrote:
>Steve Upton <upton@chromix.com>, wrote:
>
><snip>
>>  The profile connection space (PCS)- where they all hook together - is
>>  typically Lab but for many monitor profiles is XYZ. Again, not big
>>  deal as the system will handle the conversion so we tend to think of
>>  them as the same thing.
><snip>
>
>So the PCS that's actually used to connect a particular set of profiles
>together - which only comes into play inside a CMM (e.g. Adobe ACE) - is
>usually Lab. In this case the CMM will have extra work to do where a profile
>happens to use XYZ to hold it's PCS data.

To be quite honest I can't speak with a whole ton of authority on the 
form it takes within a CMM during transformation. It's like plasma, 
on earth you can only create it in a lab and even then it is not 
suggested you try to hold it in your hand. I think your understanding 
is sound though.

>  One reason for my confusion was my
>failure to distinguish between the PCS data in a profile and the PCS used in
>a CMM, and assuming that they had to be the same type.

Ah yes, well again, colorimetric data (Lab or XYZ) is what is 
important here, the units are reasonably arbitrary (at least for the 
purposes of this discussion)

>
><snip>
>>  Confused yet?
><snip>
>
>Not at all - your explanation was very helpful (as usual!).
>
>Thanks for your help.

Not a problem, we aim to please...

back to coding.........


Regards,

Steve

+--------------------------------------------------+
  Steve Upton
      upton@chromix.com

             CHROMiX / Profile Central
       www.chromix.com   www.profilecentral.com
+--------------------------------------------------+

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