Re: untagged RGB data
Re: untagged RGB data
- Subject: Re: untagged RGB data
- From: John Zimmerer <email@hidden>
- Date: Fri, 19 Dec 2003 12:24:47 -0800
Roberto,
This behavior really isn't any different from ColorSync in Mac OS 9 and
earlier. You just never noticed, since ColorSync had to be explicitly
called by an application. Whenever ColorSync is called to match an
image and there is no embedded profile, the generic profiles are used
as the source profile. That's why you can't delete these profiles --
the OS needs to have a known-good fallback for untagged source data.
The confusion is around the reason for having the ColorSync
preferences. Theses were never meant to be more than default
application preferences, not system preferences. That's one reason we
moved them to the ColorSync Utility. In other words, it has always been
up to the individual applications to look to these "default" profiles.
The primary reason that the OS (i.e., Quartz, AppKit, etc.) doesn't
look to the user-definable preferences for handling untagged color, is
that it's possible to select a "bad" default profile. The users on this
list might be able to make intelligent/reasonable choices, but the
"average" enduser might unknowingly select a profile that could wreak
havoc. Imagine if all of the sudden the entire screen became inverted,
or if white (like the default window background color) became black.
This would affect the printing system as well as the display. A bad
default profile could possibly hose the OS -- that's the down side of
having ColorSync completely integrated into the OS.
Seems to me that this issue goes away if we remove the ColorSync
preferences altogether. Only one vendor (to my knowledge) currently
looks to the preferences. That way you'd know for sure what profile
gets used for untagged images (the corresponding generic profile). For
any app calling the ColorSync preferences (e.g., Photoshop), we could
always return the generic profiles.
JZ
On Dec 18, 2003, at 8:24 PM, Roberto Michelena wrote:
>
On 12/18/03 9:29 PM, "John Zimmerer" <email@hidden> wrote:
>
>
> NOTE: untagged
>
> CMYK data is matched to the display using the Generic CMYK Profile.icc
>
> as source, and untagged gray data is matched to the display using
>
> Generic Gray Profile.icc as source.
>
>
So it's not what has been set as "default" profiles in ColorSync
>
Utility,
>
but rather the actual file called "Generic CMYK Profile.icc".
>
This doesn't make sense; "default" is understood as "when nothing has
>
been
>
specified, use default".
>
So when untagged, it should use the default. Meaning, what the user has
>
selected as default in the utility.
>
And actually the same should happen for RGB, but I can understand not
>
doing
>
so for performance reasons.
>
>
Anyway: if I want to force Untagged CMYK data to my default, can I just
>
rename my CMYK profile of choice to "Generic CMYK Profile.icc" and
>
replace
>
with it any other "Generic" occurrence in the hard drive?
>
Or do I also need to tweak the internal profile name?
>
Or any other internal thing?
>
>
-- Roberto Michelena
>
EOS S.A.
>
Lima, Peru
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