Re: [Openexr-devel] Introduction and CTL/ICC question

[Florian Kainz]

ICC profiles and CTL try to solve similar problems:
Pixel values in one color space are transformed into
pixel colors in another color space.

As you already pointed out, the main difference between
ICC profiles and CTL is how the transform is described.
ICC profiles use tags with fixed meanings; CTL describes
the transform as a procedure.

We favor the procedural approach because it is extensible.
Implementing new transformation algorithms should not
require changing CTL.  This allows users to experiment
with new algorithms.

In addition, CTL programs can be parameterized; a single
CTL program can represent a whole family of transforms.
This is useful for image sequences where the value of a
parameter may vary over time.  Parameterized transforms
may also be useful for programs like image viewers where
the user has control over settings like exposure or the
amount of dynamic range compression.

As far as I know, the ICC is investigating how ICC profiles
can be applied to of HDR data.  I don't know much about the
current status of this project, but maybe one of the ICC
delegates on this list can say more about it?

Florian