CMS Applications

Some high-end applications are “CMS-aware”, meaning they know how to use colour profile information tagged onto an image file. An example is Photoshop.  Starting with version 6.0, Photoshop is capable of simultaneously working with multiple images, each tagged in a different colour space. Also, a Photoshop user can select (as an application setting) a preferred “working space.”

Let’s take at look at what happens, if Photoshop is asked to open an untagged file such as a 10D JPEG file, shot with the Adobe RGB colour space selected by the photographer. The table above shows that the camera will not have tagged the image with an ICC profile. Photoshop will, therefore, display the missing profile dialogue.

Missing Profile Dialogue

Photoshop is giving the user four choices:

1. Just forget about colour management because exact colours are not important. This might be a sensible case for web graphics, or if you just don’t care about exact colours
2. If you know the working space of the image (such as with a Canon Adobe JPEG image), then tag the file with the correct profile as selected from a drop-down menu.
3. If you know the working space of the image (such as with a Canon Adobe JPEG image), then tag the file with the correct profile as selected from a drop-down menu, and CONVERT the image to the working space. (Adobe RGB in this case.)
4. If you know the working space is actually Adobe RGB (the current working space), simply tag the image to so indicate.

Assign vs. Convert

There is a subtle point here that must be understood. There is a difference between ASSIGNING a profile to an image, and CONVERTING an image to a different profile. You assign a profile to an image when you already know its working space, and simply need to add an ICC profile to tag along with the image data. None of the actual image data is changed in any way. However, when you convert an image from one working space to another, the actual image data is modified, and then an ICC profile is added to tag along with the image data.