Alkeria NECTA Series - Mode 2 (Subsampling - Color Models Only); Sum; Average

8. Capturing Images 84
be used to make calculations starting from the bare raw data coming from the sensor. Fixed Pattern
Noise (FPN) calibration remains active; its contribution can be made neutral (e.g. to evaluate a different
FPN calibration) using the methods described in Section 8.2.
8.1.3 Mode 2 (Subsampling – Color models only)
Mode 2 performs a subsampling procedure on acquired data. Sensor pixels are grouped four-by-four in
clusters called super-pixels (see Figure 8.1). Horizontal resolution is halved, thus data amount of each
row is halved compared to the same pixel format of Mode 0. Users can choose between two binning
modes: Sum and Average.
0
0’
0’
0
1
1
G
R
R
G’
R’
B’
1’
G’
R’
B’
2’
G’
R’
B’
n’-1
G’
R’
B’
2
3
G
R
R
4
5
G
R
R
G
R
R
n-2
n-1
G
B
B
G
B
B
G
B
B
G
B
B
Figure 8.1: Mode 2 subsampling
8.1.3.1 Sum
Sum mode is useful when video signal is inadequate for your application. Resulting RGB pixel is calcu-
lated as follow:
R
′
= 2R (8.1)
G
′
= G
R
+ G
B
(8.2)
B
′
= 2B (8.3)
8.1.3.2 Average
Average mode is commonly used to reduce image noise. Resulting RGB pixel is calculated as follow:
R
′
= R (8.4)
G
′
=
G
R
+ G
B
2
(8.5)