[Openicc] color management cookbook style?

[Carol Spears]

On Mon, Apr 18, 2005 at 03:20:22PM -0700, Hal V Engel wrote:
> On Monday 18 April 2005 01:52 pm, Carol Spears wrote:
> >
> > where are the tables?
> >
> 
> 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.
> 
it makes sense to me that image files are binary.  they are created by a
computer for the computer.  even these files are becoming more and more
easy to manage with a simple text editor.

what i would like a couple of examples of is the information that is
used to create these profiles.  binary at the point between a different
device and a computer makes no sense.  there is information about the
device and it is put into a certain format that can be easily read.  the
math is complicated, i can see this.  i understand the reason that
profiles are binary.  it will be easier for me to just believe after i
step through it.  right now, all i really believe is that i have someone
elses math and opinions and methods all bundled up into something that
other people believe in.


> 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.  
> 
thanks, i have a handful of these.  i chuckled when i got a generic cmyk
glossy paper profile.  i dont think i need to take the time to figure
out what lcms can tell me about that.

> 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.  
> 
i bet making the profile is difficult.  getting the first set of
information from the printer is old stuff though.

i am saving up for a colorimeter.  i am sorry i do not have the access
to the gaschromotography equipment i have had in my past as well.
between the time that i can afford color reading equipment and now, i
thought it would be useful and interesting to look at the information
that is available about the devise(s) in the pre-profiled form.

> 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.
> 
the majority of the users of TheGIMP do not need real color management.
i would like to think that the majority of them also know that they dont
need it.  it might even be 99% of the users who do not need it.

as a user, i am one of the 99%.  if i want a good print of something, i
know how to get it.  however, i am also here for the 1% of the users who
know what color management is and really do need it.  

> 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. 
> 
spending time on www.normankoren.com is what made me start to look for
the actual information.  so early in the explanation of color management
it breaks into "this profiling company uses these types of color samples
and this many of them and this other company uses these colors this
way".  this is the part where i want to see which color samples indeed
give the better information.

i can see you did not like my tofu stuff, here is more of that.  when i
was teaching astronomy lab at my college, they retested the speed of
sound and found they had been a full half a mile per second off.  

we might have a problem because i do not want to use the same tools you
are using.  it should not be a problem.


> 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.
> 
on gny/linux, i read about how everyone else does it.  it reads like
gobbly gook much of the time.  other times, it looks suspiciously like
an infomercial.

carol