I'm getting efficiency more than 100% for my camera in ISOs higher than 6400. Under what circumstances does one get more pixel values than the number of incident photons (photon detection efficiency more than 100%)?
P.S. I removed the IR filter from my Nikon D3s and now have a fog covered the CMOS and I'm using dcraw to get the raw pixel values out of the raw image.
Ref. to IR fog: Bright image with infrared D3s and cap on (image included)
UPDATED: Thanks for the contributions, I guess I've got to emphasize on couple of thing: 1- I'm not trying to calculate Quantum Efficiency but the photon detection efficiency (one can calculate one from another by knowing about geometrical efficiency and Geiger efficiency). 2- I know the exact number of incident photons by an acceptable uncertainty. 3- I guessed it could be some digital amplifications, but then it should be well calibrated for such DSLRs and considering that I'm not saturating the pixels.