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

[Arnie Cachelin]

On Tuesday, July 29, 2003, at 06:21  PM, James H. Cloos Jr. wrote:
> 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.

Just to throw in some uninformed speculation,
I'm not sure cooling or S/N improvement is important for adding the bit 
depth needed for HDR imaging, since the CCD noise will impact the 
lowest intensity signals, while the bits we really need are in the 
super hot areas of the scene.  Sure if the sensor is behind many layers 
of ND filter attenuation, so the sun is a 1.0 white spot, then all the 
details will be swamped in shot noise, but that does not seem like a 
clever solution.   More useful, IMHO, would be a method for polling the 
CCD multiple times per image, so that the hottest points would have at 
least a few unsaturated samples taken.  This would essentally be a 
method for measuring multiple exposures from a single 'shot'.