[Openexr-user] storing an EXR image in memory

[Enrico Borrione]

hiya all,
I am starting playing with EXR files and having much fun indeed. I made
up a little demo based on the exrdisplay program that gave me quite a
good feeling. Anyway it isn't yet the kind of thing I was wondering of,
so i am thinking about some more complex stuff ( -> more work closing in
fast).

I have a couple of questions so far:
1) again on exrdisplay rendering pipeline (someone of you may remember
me, i was posting as tensor g): I studied the whole code and the only
question remaining is, do i really need the knee function? Actually I
made some tests, but i can't really see much difference between an app
running the knee and one that doesn't. Just wondering if i may be able
to cut a bit on that code, but yet afraid of leaving back some necessary
stuff... ;)

2) i have been reading some specs, lately, and i came across some
articles talking of hdr images. In particular they was refering to some
nvidia memory buffers called HI LO, that should provide a facility to
store hdr images in "raw" format in memory. Actually i think it wouldn't
be *so* smart loading an exr image, process it into an 8bit texture and
then use the latter in my texturing: no point to load 16 halfs and then
using just 8 exposure-calculated values...
Finally the question: how can i store in memory the full 16 bits of the
texture?  I'd like to put all the data into a cubemap, just to handle
'em more *comfy*, but i am afraid that that usual GL_CUBE_MAP_ARB just
won't accept Halfs. 

3) Refering to the nice answer Florian Kainz gave me some days ago:

> Given an OpenEXR file's "chromaticities" and "whiteLuminance"
attributes, the code snippet below computes a pixel's absolute luminance

now how do I extract chromaticities and whiteluminace values??? Sorry 4
being *so* lame, but it is the first time i ever face image
processing...

As usual thx to all the hints will come by :)

see ya E.