® 8k/4k CL Color
32
e2v semiconductors SAS 2014
Gain
:
(
Gain
with
GainSelector
=
GainAll
)
Set the Amplification Gain. This command is available in the CommCam “Gain & Offset” section :
Read function : “r gain”;
Returned by the camera : Value from 0 to 6193 corresponding to a Gain range of 0dB to +8dB calculated as following
: Gain(dB) = 20.log(1+ Gain/4096).
Write function : “w gain” <int> ;
Tap Gain (
Gain
with
GainSelector
=
Tap
X) :
Read function : “r fga<tap>”; <tap> is 1 or 2
Returns the Gain value for the tap. Ex : “
r fga1
” returns Gain value Tap1.
Write function : “w fga<tap> <value>”
<tap> : 1 or 2
<value> : from -128 to +127 by step of 1 (0,0021dB each step)
Digital Gain (
Gain
with
GainSelector
=
DigitalAll
) : Set the global Digital Gain. This command is available in the CommCam
“Gain & Offset” section :
Read function : “r gdig”;
Returned by the camera : Integer value from 0 to 255. The corresponding Gain is calculated as 20log(1+val/64) in
dB
Write function : “w gdig” <int> ;
Digital Offset (
BlackLevelRaw
with
BlackLevelSelector
=
All
) : Set the global Digital Offset. This command is available in
the CommCam “Gain & Offset” section :
Read function : “r offs”;
Returned by the camera : Value from –4096 to +4095 in LSB
Write function : “w offs” <int> ;
Tap Balance Gains Enable Switch (
TapBalanceGainEnable
) :
Read function : “r fgae”;
Returns the Tap Balance Status.
Write function : “w fgae <val>” with <val> : 0 or 1
0 : Disables the Tap Balance Gains
1 : Enables the Tap Balance Gains
6.3.4.1
White Balance
As described in chapter 6.3.2, the structure of the sensor differentiates Green pixels facing Blue or Red pixels.
Then the white balance is associated with 4 color Gains :
-
Red
Gain
-
Green
Red
Gain
-
Green
Blue
Gain
-
Blue
Gain
The Color Selection or enabling (Image Format Chapter) can affect the way you’re performing the white balance :
For example, if you disable the Blue and the Red color, the “White Balance” will be performed only between the
two Green Gains.
The dissociation of Green (blue) and Green (Red) is justified by the possible difference of response of the two
types of Green because of their respective neighbor color influence and then the necessity to tune them
separately.
As usual, for a perfect White balance, provide to the Camera a non-saturating white (gray) target in the center of
the sensor.
The White balance has to be performed after the Flat Field Correction as each color is performing its own FFC with
its own reference.
In any case, the best tuning of the Camera Gains is performed from the left to the right of the Gain Chain described
above : Preamp Gain first and quarter Gains last (if required).
