[Radiance-general] Re: convert camera exposure to radiance

[Randolph M. Fritz]

On 2010-08-18 04:07:52 -0700, jelle feringa said:

> I'd like to do the inverse, and use my camera as an approximate 
> radiance / lux / candela measuring device.
> I realize this is pretty approximate, but that will do for now.

See Kodak's "Estimating Luminance and Illuminance With Reflection-Type 
Exposure Meters and an 18% Neutral Test Card" at 
<http://www.kodak.com/cluster/global/en/consumer/products/techInfo/am105/am105kic.pdf>

Since 

modern digital cameras record their exposures, the gray card is 
unnecessary, and the calculation can be automated, as Greg has done in 
Photosphere. One thing to keep in mind is that a camera exposure 
calculation may use different spectral weights than a luminance meter.

Randolph