Daniel Rogers wrote:
There may be some worth in considering including other kinds of
information in a pixel besides alpha.
In addition to alpha (the measure of coverage) you could also include
transparency (which is something a measure of how much light passes
through, i.e. the actual transparency of glass, as opposed the the
coverage of a screen, this is equivilent to insisting on a layer mask to
be included for every layer).
It is a little tempting, as it would remove a lot of ambiguity in
the overloading of the meaning of the alpha channel. We've
(well, GIMP and probably most other transparency-handing packages
out there) been equating transparency with alpha for so long now
though that I'd hate to have to re-educate users. But it needn't
be something that the front-end has to expose.
We could also include luminesence, which
is a measure of how much light a pixel produces (as opposed to
reflectance, which is all we measure how with rgb).
There are various per-pixel properties I could think of which might
be very exciting (surface normal vector, specular reflection index)
especially for natural media rendering. Luminescence wouldn't be
the first that'd come to my mind, since I think that any such image
elements would by nature be quite isolated and fit very well on their
own 'addition' style layer and save a lot of complexity, but
perhaps it would be nice to paint with fire after all...
--
Adam D. Moss . ,,^^ adam@xxxxxxxx http://www.foxbox.org/ co:3
busting makes me feel good
kthx bye
