[Openicc] color management cookbook style?

[Hal V Engel]

On Monday 18 April 2005 01:52 pm, Carol Spears wrote:
> hello,
>
> i have been very respectfully reading the email on this list.
>
> i also have access to a text book and all of the print "how tos" and
> "how they do this" documents that search engines & my attention span
> can gather.
>
> when it comes to software, i tend to stop when i see a binary file.
> especially when i have access to the formulas that were used to create
> the file.
>
> in real life, i followed the recipe to make tofu once.  it was very
> difficult and for hours of work and many soy beans, i was only able to
> make about 2 tablespoons of actual product.  i now gladly purchase this
> premade and am grateful to a world in which this substance is plentiful
> without me having to work that hard for it.
>
> you can read and read and read about how one way is better than the
> other or how they both have their different good points and bad points
> ...
>
> where are these icc tables anyways?
>
> lcms converts from one binary format to another.  this is a miracle to
> me.  my hats off to the lcms developers.
>
> until i actually see the tables everyone is working with and do the
> conversions by hand a couple of times, i am not going to ever believe in
> this stuff enough to learn all of these new acronyms.
>
> where are the tables?
>
> thanks,
> carol
>

Carol,

ICC profiles are binary files that contain the information needed to map color 
between various color spaces.  They are not directly human readable but there 
are tools that will allow you to look at the contents.  I don't know of any 
that are available for open source systems off hand.  But if you do a little 
googling you will be able to find a few that are freely available for Windows 
and possibly the Mac.  There might even be web sites that are setup to allow 
you to inspect profiles.

If you would like I can send you any number of profiles but these are very 
easy to find on the internet and from other sources.  In reality these 
generic profiles are not very useful in and of themselves.  And in particular 
you really do need custom profiles for your devices and a good work flow for 
this to work correctly.  

Printers are difficult to profile.  But it is possible to purchase custom 
printer profiles on-line from a number of sources for reasonable fees.  You 
send a printed target to them and they ship back a profile.  Things like 
scanners and cameras are easy to profile.  Monitors are in between and you 
need a colorspectrometer to do this correctly along with profiling software.  

One of the more difficult aspects of CM is that there are implications in how 
this affects your work flow.  In fact when using manual CM work flows like I 
do now it has a huge impact.  If it did not result in an equally large 
improvement in my results I would not be doing all of the extra work 
required.  In reality, the extra work to do a CM work flow actually saves me 
time in the long run as well as giving me much better results.

There is also a significant learning curve when you start to delve into CM.  
It touches almost everything on a system and if you are doing color critical 
work every aspect of your work flow.  Proper color management even requires 
that you use the right kind of lighting.  So even the room you work in 
matters.  For a real good overview I would suggest that you visit 
http://www.normankoren.com  He has perhaps 6 or 8 web pages that deal with 
aspects of color management from a user perspective and it is well written 
and accessible for those who are just starting with CM.  Unfortunately, all 
of his examples are very Windows centric so when he starts getting into some 
of the more detailed stuff it might be a little difficult to follow unless 
you are also using the same tools (or have in the past).  But the 
introductory sections are general enough to be usefull to anyone no matter 
what software they are currently running. 

On Windows I use a tool called ProfilePrism to create printer profiles.  The 
reason that I bring this up is that ProfilePrism installs a DLL named 
lcms.dll and we all know where that came from.   I might add that Argyllcms 
also adds some things to the CM mix as it has the ability to create profiles, 
which lcms can't do,  as well as doing some of the same things a lcms.  So we 
allready have the foundation that is needed to build everything else.

Hal