Re: [Openexr-devel] Query: Image Based Lighting and HDRI-enabled cameras

[James H. Cloos Jr.]

>>>>> "Brian" == Brian Willoughby <address@hidden> writes:

Brian> What about pixel depth?  Will we ever see 12 bits per component
Brian> in an HD camera? 

12 bit may require that the imager be cooled, else noise may
overwhelm.  I have seen reports or a website or something at
least a couple of years back where a peltier cooler was used
to improve a ccd's noise floor enough to allow a better bit-
depth.  IIRC the pwoer requirements were too much for use in
many portable applications, notably including the consumer &
prosumer markets.

If the power requirements can be controlled I am sure 12 to
16 bit imagers will be feasible.

Brian> I understand that the HD cameras that Lucas
Brian> used have 10-bit CCDs, but only store 8 bits per component on
Brian> tape due to the compression.  That's why he had custom storage
Brian> hardware built to take the live 10-bit uncompressed outputs and
Brian> store that data without truncating to 8-bit (or compressing in
Brian> a lossy fashion, either, I suppose).

That is of course why you want to grab the raw data from the imager.
A lossless compression asic/fpga/cpld would remain beneficial, of
course, just to ensure the storage devices can keep up.  (The
fastest SATA drive I've seen (WD's 36G drive) can do up to
100 Mbit/s to/from the platter.  That allows about four
megabits per frame at 24 fps.  At 10 bit raw that
means about 720x540 pixels per frame.  (NB
that for a 1 ccd camera you only get 10
bits per pixel in raw formats; you
have to interpolate to get the
full data.)

Brian> I think we have a while before CCDs produce 16-bit half float
Brian> values (HDRI),

Getting floats directly from the imager will be an engineering feat.
Are there *any* ADCs in the wild that sample into floats?

Perhaps sampling the log of what is currently sampled would do?

-JimC