Re: CMMs in Profiling apps
Re: CMMs in Profiling apps
- Subject: Re: CMMs in Profiling apps
- From: Graeme Gill <email@hidden>
- Date: Tue, 18 Jan 2005 00:08:04 +1100
- Organization: Argyll CMS
Roberto Michelena wrote:
If I remember well, at least some former profiling application (was it Agfa
Colortune?) allowed selection of the CMM used during profile building.
Because it seems obvious that a profiling application needs access to a CMM,
if not to build the profiles, at least to verify them and give all those
statistics.
In creating a profile for a device, it doesn't make much sense to use a
system CMM. CMM's generally don't have the facility to create device profiles
(that's what the profiling applications specialize in), and even though most
CMM's have some sort of facility to write a profile, this is often at a low
level (ie. the CMM is handed data in almost exactly the form written to the
ICC profile). This means that it is usually the profilers job to craft the
actual binary values that are written to the ICC profile, leaving little scope
for the CMM to exert any influence on the result.
Yes, another CMM could be used in a supplementary verification pass, but I'm
not sure if that leads you anywhere useful.
The theory of recording the CMM in the profile, and allowing different
CMM's to be selected to interpret profiles, was that it allowed certain
vendors to add "secret sauce" to their profiles (in the form of
private tags), and then interpret those tags to give a superior result
to that obtained by using just the standard public tags. The intention I'm sure
was that the interpretation of the standard public tags would be unambiguous,
and that therefore all CMM's would give the same results when interpreting
profiles created by a different CMM. In practice this turned out not to
be the case, although I think things are generally better than they were.
ICC V4 attempts to reduce the scope for such differing interpretations,
but time will tell whether it achieves this aim, or just complicates things
some more.
But then, it seems that most would use its own internal CMM, in other words,
ProfileMaker would use a gretag CMM flavor, PrintOpen a Heidelberg one, and
so on. Because I wouldn't count on any using the Microsoft CMM?
Almost certainly, because it is going to verify against the profile
using it's "secret sauce", indicating the best possible result.
The question I have is of multiplatform profiling apps... will they produce
exacly the same profile, and yield exactly the same statistics after
building it, regardless of platform? will I have the very same results on
Monaco Profiler, for example, regardless of whether I'm using it in Mac OSX
or Windows XP?
Probably.
And will I have the same preview when doing profile edits? (if I were using
the same monitor calibrated by the same sofware and instrument, of course).
Possibly. It depends whether the software itself completely takes over all
aspects of the color management (Adobe Apps tend to be this way), or
whether it relies on other system components to do some of the work (ie. in
the process of displaying images.)
There are some system differences that are harder to work around, such as
the poor standardization of monitor calibration. Apple Mac's uses a private
tag to store lookup curves (but not other parameters that might be used in
DCC connected monitors), but MS Windows and X11 are much less standardized in
this regard. Lots of scope for stuff not working.
Graeme Gill.
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