Re: Null Profile?
Re: Null Profile?
- Subject: Re: Null Profile?
- From: Steve Upton <email@hidden>
- Date: Sun, 11 Nov 2001 21:43:42 -0800
At 8:00 PM -0800 11/11/01, JWL wrote:
What if I try to create a null input profile, though? Say if I edit a target
capture so that the patches are all the same as the lab values of the target
data file, then feed this to the profile creation software. Would the
resulting profile would be "null", having the same effect as not specifying
a source profile, i.e., no conversion?
The target capture values are in RGB and the data file values are in
Lab. There would be no way to edit the target capture values to be
"the same".
This also brings me to a point I've been meaning to post.
There is, by the definition of how this stuff works, no such thing as
a "null" profile when dealing with device profiles. Device profiles
convert from Lab (or XYZ) to device space or device space to Lab.
There is no way to create a profile that will have no effect (null)
as it will have to convert from a colorimetric value to a device
value or vice versa. It's like converting this sentence to French and
hoping it will have no effect. Even if the meaning is the same and it
could be translated back it would still be in French.
ColorSync does come with generic profiles that are considered to be
"generic" by someone @ Apple but they certainly do have an effect,
even if they are applied twice - eg RGB->Lab->RGB. If you apply them
in one step then ColorSync detects this and does not perform any
conversion. But, strictly speaking they do have an effect.
The only profiles that you could create as "null" are abstract
profiles - like Lab->Lab or certain flavors of device link profiles -
RGB->RGB or CMYK->CMYK
Bruce's idea is probably your best bet as you can tell the camera
software to convert from aRGB->aRGB and it will either a) not convert
at all if ColorSync is doing the work or b) convert and convert back
with some rounding errors but basically intact. I've used the same
technique when I found that the Nikon Capture software treats
incoming data as NTSC. We just applied the NTSC profile as the
destination and then did our color management outside of the Nikon
software...
Regards,
Steve
________________________________________________________________________
o Steve Upton CHROMiX www.chromix.com
o (hueman) 866.CHROMiX
o email@hidden 206.985.6837
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