Compute exposure value for current optics and image sensor array
EV = exposureValue(optics,isa);
Exposure value depends on f-number and exposure duration.
EV = log_2( (f#)^2 / expT )
where
f# is the f-number of the optics
expT is the exposure duration in seconds
Example:
optics = vcGetObject('optics'); ISA = vcGetObject('sensor');
exposureValue(optics,ISA)
Copyright ImagEval Consultants, LLC, 2005