Re: RGB Spaces
Re: RGB Spaces
- Subject: Re: RGB Spaces
- From: Henrik Holmegaard <email@hidden>
- Date: Sun, 6 Oct 2002 09:54:30 +0200
"Pablo Roufogalis L." <email@hidden> wrote:
>I'd guess this is a legacy thing from when it was common sense that
the RGB
>space for editing was the same as the RGB space for the monitor: I have
>noticed that the profiles for RGB spaces are defined as monitor spaces
and
>even include numbers for raw phosphors colors.
The ICC Specification offers seven classes of profile:
scnr for scanners and cameras
prtr for printers
mntr for monitors
The above are the device classes, and the non-device classes are:
link for device links
spac for color space
abst for abstract
nmcp for named color profile
The first reason for choosing the monitor class was that a class was
needed which would support RGB as device space and bidirectionality for
separation and simulation.
Of the device classes, scnr is only required to be unidirectional from
device space to connection space, so you cannot use an scnr profile to
simulate another space because you cannot convert into an scnr profile.
Printer and monitor profiles are required to be bidirectional, so you
can convert from one of these spaces into the connection space and from
the connection space into one of these spaces. Thus the Adobe InDesign
2.0 manual states that only bidirectional profiles may be used as
working spaces.
The second reason for choosing the monitor class over for instance the
color space class was that it suited the Photoshop CMS at the time.
Printer profiles must be table-based in the ColorSync 2.0 and later
format, and monitor profiles may be matrix-based or table-based. RGB
working spaces are idealized, matrix-based monitor spaces. The approach
through a simplified gamma model reproduces gray for R = G = B and has
historical reasons in the Photoshop CMS which are no longer important.
Hope this helps.
_______________________________________________
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.