Re: [Gimp-user] ICC Profiles: UFRaw + GIMP => 2x correction?

[Kevin Brubeck Unhammer <unhammer fsfe org>]

Gary Aitken <gimp dreamchaser org> writes:

> Humor me, and try the following:
>
> Scenario 1:
>
> Load a raw image into ufraw with some feature for which you can tell a
> difference when a profile is applied.
>
> Apply the profile in ufraw.
> Save the file as .tif
>
> Start gimp.
> Go to Edit/Preferences/ColorManagement
>   Make sure RGB Profile is set to "None"
> Load the .tif image.
> It should look as the corrected image, i.e. profile applied.
> Go to Edit/Preferences/ColorManagement
>   Check RGB Profile
>     It still says "None"
> ok so far
>   Presumably the profile used is the one embedded in the .tif image.
>   But there is no way of knowing what that profile is or whether it
> has been applied that I can figure out.

When I apply an Output Profile in UFRaw and send to GIMP, GIMP asks me
whether to keep the embedded profile or convert to sRGB, so I do know
that it's noticing a profile there. You can set GIMP to ask on the
bottom drop-down of that menu.

Also, just to check "if it's plugged in", if you run ImageMagick's
"identify -verbose myfile.tif", does it have a section like

     Profile-icc: 3004 bytes
       Description: Pink
       Manufacturer: IEC http://www.iec.ch
       Model: IEC 61966-2.1 Default RGB colour space - sRGB
       Copyright: Copyright (c) 1998 Hewlett-Packard Company Modified using Adobe Gamma

?

Or, if you click Image→Image Properties (alternatively:
Image→Mode→Set/Convert Colour Profile), does it say that the current one
is sRGB built-in, or that it is YourProfileName?

> Now set the RGB Profile to the one you used in ufraw when generating
> the .tif image.
>   You will see the image transformed again.
>   In effect, the profile is being applied twice.

I don't see this. What I do see is that no matter what crazy embedded
Output Profile I use in UFRaw (and I select "keep embedded" in GIMP),
changing the RGB Profile in that part of GIMP doesn't change what the
image looks like, and they all look the same no matter what profile they
have (or even if they don't have a profile).

However, if I open an image without an embedded profile, clicking
Image→Image Properties tells me that the profile is "sRGB built-in", and
if I have RGB Profile set to something weird in Preferences then, the
image gets weird colours.

Tested using UFRaw version 0.18, GIMP version 2.7.4, on Arch Linux.

> BTW, I'm using gimp 2.7.5 (2.8 preview); I don't know if this is
> specific to 2.7.5 or not.  It may also be that these are temporary
> issues with the transition to full color management and 16bit colors.
> But if they are issues not already on the gimp development plate, they
> should probably be raised so they are at least well-known.

Ah. Perhaps the difference is to do with Windows?


-- 
Kevin Brubeck Unhammer