[Elphel-support] FPN correction

[Jens Bürger]

Hello everyone,

we try to use the FPN correction.
However, in the comments of x353.h is denoted:
...

// [2:0] scaling of 11 bit FPN result to fit in 8bit output:
// 00 - default - use [9:1]
// 01 - use [10:2] - to protect from saturation after applying mpymode //      nominal range - 0..127
// 10 - use [7:0] before saturation, "digital gain" == 4 (maximal) // 11 - use [8:1] before saturation, "digital gain" == 2

...

This is a bitvector three bits wide, but the meaning of only two bits is explained. Where is the third bit? :)

Additionally, we found the fpns and fpnm PHP parameters; do they work as explained in 
http://wiki.elphel.com/index.php?title=Ccam.cgi
?

Is there a difference between these two FPN correction settings?

Thanks in advance,

Jens