[Openicc] _ICC_PROFILE in reality

[Graeme Gill]

Chris Murphy wrote:
> I just expect the OS to handle it. The problem with apps having to do
> something special to make it work is that so few developers do.

I think this would be possible, but the OS graphic support would
have to be sufficiently enlightened. For instance, it would
be necessary for the graphics system to allow arbitrary
source pixel representation by the application, and then
allow the application to set a device link type transform
from that space to the display. The OS/Window manager could then
manage the spatial aspects. This leaves the application in full
control over the color transformation. Complications are
that typically what an application has to display is a composition
of different elements. Certain image data may be in an arbitrary
color space with a desire for high fidelity color, but there will
be other elements defined in different color spaces that need to
be composited together. You end up with the need for quite a
sophisticated compositing system. I suspect that many of
the current display composting systems fall short of what I've described
above in two ways: They don't support arbitrary source representation
(ie. they all assume 3 component sources), or they don't support
an device link transform (ie. they assume ICC source profile +
destination profile).

When the application handles the whole deal and transforms its sources
into the device dependent display values, it at least has the possibility
of getting it right. The developer has to care to do so though.

Graeme Gill.