UM_NBASE-T_C
OLOUR
REV.E
09/2018
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48
7.8
Flat Field Correction Control
7.8.1
FFC Calibration and Bank/Preset Saving
How is performed the Flat Field Correction ?
What is the Flat Field correction (FFC) ?
The Flat Field Correction is a digital correction on each pixel which allows :
To correct the Pixel PRNU (Pixel Response Non Uniformity) and DSNU (Dark Signal Non
Uniformity)
To Correct the shading due to the lens
To correct the Light source non uniformity
Before
After
How is calculated / Applied the FFC ?
The FFC is a digital correction on the pixel level for both Gain and Offset.
Each Pixel is corrected with :
An Offset on 10 bits (Signed Int S9.1). They cover a dynamic of
256LSB in 12bits with a
resolution of 1/2 LSB 12bits. Offset : the MSB is the sign, the rest of 9bits is from 0 .. 256 with
precision of 1/2
A Gain on 14 bits (Unsigned Int U1.13) with a max gain value of
x4.999
The calculation of the new pixel value is :
P’ = ( P + Off).(1 + Gain/1024).
Gain : 0 to 4095
Standard FFC computed on the max of the line for each color (Green
Blue
and Green
Red
are treated
separately). Then the White Balance will overlay the colors
Pixels
