gimp-user  

Re: [Gimp-user] Color profiles & color spaces -- assignment v. conversion?

David Gowers
Thu, 17 Jul 2008 03:23:18 -0700

Hi Hedley,

On Thu, Jul 17, 2008 at 4:22 PM, Hedley Finger
<[EMAIL PROTECTED]> wrote:
>
> I know just enough about colour management to get myself into trouble.
>
> On Gimp 2.4.6, there are now some new options under the Image > Mode >
> menu path, namely
>
> @   Assign to Color Profile // Actually uses Little CMS (lcms)
> @   Convert to Color Profile // Actually uses Little CMS (lcms)
>
> @   Assign colorspace  // Hmmm, should be 'Color Space' for niceness?
> @   Convert colorspace  // Likewise!
>
> At the moment there are no Help topics nor topics on the User Manual
> site for these menu options, so can some Photoshop, graphic arts, or
> prepress guru assist with these queries:
>
> @   What does *assigning* an image to a colour profile do and what
> effect does it have on colour management downstream?
It changes the meaning of the pixel values. Generally this means the
image looks different.

> @   How is *converting* an image to a colour profile differ from
> "assigning", and what effect does it have on colour management downstream?
Converting, instead of assigning a different meaning to pixel values,
converts the pixel values from the previous color profile to the
profile you specify, so that the result is as close to identical as
possible to the original..

> How is assigning or converting a *colour space* different from a
> *colour profile*?  The options appear to be the same as for colour
> profiles.
There is no difference.

>
> Are these two sets of lcms and Gimp dialogue alternative ways of
> getting the same result on the image, or is one set changing the image
> file and the other is actually doing something to the profile files
> (aaaarrgghhhh!)?
No.

David
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