Estimate the signal current density (current/meter^2) across the sensor surface
scdImage = signalCurrentDensity(OI,ISA)
This image has a spatial sampling density equal to the spatial sampling
of the scene and describes the current per meter.
We perform the calculation two ways, depending on image size.
If the image is less than 512x512, we calculate using a quick matrix
multiplication. To restrict memory use, if the optical image exceeds
512x512, we loop through the wavebands. Slower, but it means the memory
used stays below 64MB
Computational steps:
The irradiance image is multiplied by the spectral QE information.
The calculation treats the input data as photons, estimates the fraction of
these that are effective, and then turns this into a charge per unit
area.
Subsequent calculations account for the photodetector area.
There are many comments in the code explaining each step.
Copyright ImagEval Consultants, LLC, 2003.