1) p is photons. Duh! What is the name of those things we're trying to capture again? :P
2) Gain.
Okay why can't I maths this out? It makes sense that unity gain is where 1 electron in = 1 ADU out (power in = power out). This results in 4096 levels for 12 bit, which corresponds to 4096 photons.
I can't figure out how the number 139 relates to that. Padding with 4 LSB bits just multiplies the total by 16, right? So 139 * 16 = 2224.
Which is still not 4096.
I understand that the spreadsheet works and this is just my mathematical shortcomings, but I wish I understood how they got that number. As far as I can tell unity should be at 4096/16 = 256 which is wrong, I know, but I don't quite know why...
Markus
