LAB as working/interchange space
LAB as working/interchange space
- Subject: LAB as working/interchange space
- From: Roger Breton <email@hidden>
- Date: Thu, 31 May 2001 09:00:06 -0400
>
> To which Roger Breton adds:
>
>
>
> There are no transformation involved here, Chris. The experience I relate is
>
> that of displaying an already converted CMYK image in Photoshop 6 as opposed
>
> to opening the same image in LinoColor, ProfileEditor and ColorFlow!
>
>
Must I point out that CMYK->LAB is also a conversion, and also has an
>
intent, and has a choice of black point compensation, and has a
>
choice of CMM?
I think I have not clearly explaining myself, here. The case I am trying to
describe is that of "opening" a CMYK file from disk. The way I understand it
is that, upon opening, Photoshop needs to determine what to do with the
embedded profile it finds in the CMYK file (let's assume there is one). It
needs to do this because the user choice of CMYK Working Space is set to
something other than the embedded profile (Policy set to Preserve and ask
upon opening). The user then instructs Photoshop to use the embedded
profile.
Is there actually a "conversion" taking place at that stage? Doesn't the
CMYK pixels remain unaltered? Doesn't Photoshop only need to figure how to
display those CMYK pixels on the monitor? And correspondingly resort to the
A2B1 Tag supplied in the embedded ICC profile (Device to PCS - "ICC Lab")?
Further, the Lab readouts in the Info palette becomes the values off that
A2B1 Tag or the values of the CMYK Working Space?
--
Roger Breton
Quibec Institute of Graphic Communications
Montrial (Quibec) Canada T. (514) 389-5061 F. (514) 389-5840
email@hidden