[argyllcms] Re: Eye of Gnome Color Management

On Mon, 2009-03-30 at 17:54 -0700, Hal V. Engel wrote:
> On Monday 30 March 2009 02:28:01 pm Leonard Evens wrote:
> > I have been confused about whether or not Eye of Gnome, under Linux,
> > supports color management.  There seemed to be several bits of seemingly
> > contradictory evidence.
> >
> > 1.  eog definitely shows something different on the display from what
> > gimp, inkscape, and Firefox, all of which agree, show. The last three
> > programs can be configured to get the display profile from from the
> > system, and they show exactly the same thing for any image file.   If I
> > tell those  programs not to use the display profile, then what they show
> > looks exactly like what eog shows.
> >
> > 2.  Searching the source code for eog does bring up icc strings.   I
> > believe it may also show it making an attempt to get the profile from
> > the system, but I'm not sure about that.   I didn't try to actually
> > understand the code, looking instead just at function calls which seemed
> > relevant.
> >
> > 3.  At the suggestion of a couple of previous responses to my posts, I
> > tried looking at certain test files as recommended, and the results
> > seemed to confirm that eog was using color management information.
> >
> > 1 seems inconsistent with 2 and 3.   But I believe I may have discovered
> > one possible source.    Searching the eog development archives, I found
> > notes to the effect that color management only worked for files with
> > imbedded color profiles.  (This is considered a defect.)
> 
> This condition is not defined by any standard since one part of the transform 
> is not defined (IE. the missing embedded profile).  But in some cases 
> applications will make the assumption, and we all know what they say about 
> assumptions, that any image with no embedded profile is some "standard" color 
> space like sRGB but this could also be wrong.  Think of it like this:
> 
> Given 
> 
> X + Y = Z and Y = 5 
> 
> how would you figure out what Z is?  Of course you can't and this is 
> analogues 
> to: 
> 
> Image with no embedded profile (X) transformed into (+) the monitor color 
> space (Y) = the transformed image (Z ?? who knows what this should be).   
> 
> To solve for two unknowns you need at least two equations involving those 
> unknowns and in this case there is only one equation.

I see your point.  But why can't eog do what gimp, inkscape and firefox
do?

> 
> > I don't know
> > if that means it uses only the imbedded profile or if it means that it
> > will only make use of the system display profile if there is a profile
> > of any sort imbedded in the file, e.g, an sRGB profile.    It may be
> > that the image files I've been testing with don't have imbedded
> > profiles.
> >
> > Any comments?
>

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