Camera and beamshot as lightmeter using software ?

[KreAture]

I had a look at some of the math and essentially both the sensitivity and view of a digital camera is quite well defined. A program reading an image could extract sensitivity setting, shutter speed, focal length, aperture and pixel intensity from a beamshot and integrate this to create a lumen/candela reading for the light output...

What is needed is to calculate the pixel intensitys relative to a given distance and angular resolution of each pixel. Corrections would have to be made based on the lit surface but if one used some standard paper/matte this should be quite accurate.

So, do we have a coder among us that would like to give it a go?

Would be nice to have an application that given few inputs and a picture could tell us the actual light output and spot power of any torch...

A place to begin regarding the math would be wikipedia. Looking up digital slr, field of view and lumen/candela for starters.