Photon Focus MV1-D2048-3D03 Series, User Manual, Page: 77 / 131

5.7 Column FPN Correction
5.7 Column FPN Correction
The camera contains a correction to decrease the Column Fixed Pattern Noise (FPN) of the
sensor. By default the Column FPN Correction is enabled.
The Column FPN Correction of the camera is correctly calibrated at the Photonfocus production
facility. Although a new calibration is normally not required, the user can recalibrate the
Column FPN Correction. No light should be applied to the camera during calibration. The
average grey value of every column of the image is calculated. The difference to the average
grey value of the whole image is then calculated for every column and stored in internal
camera memory. After calibration, this difference is then subtracted column-wise from every
image to reduce the Column FPN. Detailed instructions on the calibration of the Column FPN
Correction is given in Section 7.7.
5.8 Outliers Correction
Defective pixels of the image sensor might appear as dark or bright pixels. Although this is not
common, a defective pixel correction (Outliers Correction) is implemented in the camera. By
default the outliers corrections for black pixels and for white pixels are enabled.
A pixel is labeled as a black pixel if the grey value is smaller than the parameter BlackLimit and
the grey value differences to its two neighbours on the same row exceed the value of the
parameter
BlackDiff
(see Fig. 5.40). The Black Pixel Outliers correction can be enabled or
disabled by a property (see also Section 7.8). If it is enabled then a black outlier pixel is
replaced by the mean of the grey values of its two neighbours on the same row.
Similarly a pixel is labeled as a white pixel if the grey value is bigger than the parameter
WhiteLimit and the grey value differences to its two neighbours on the same row exceed the
value of the parameter WhiteDiff (see Fig. 5.40). The White Pixel Outliers correction can be
enabled or disabled by a property (see also sec_gui_outliers_corr). If it is enabled then a white
outlier pixel is replaced by the mean of the grey values of its two neighbours on the same row.
B l a c k P i x e l C o r r e c t i o n
R a w i m a g e
I n t e n s i t y
B l a c k L i m i t
D i f f L e f t
D i f f R i g h t
D i f f L e f t > B l a c k D i f f A N D
D i f f R i g h t > B l a c k D i f f
C o r r e c t e d i m a g e
W h i t e P i x e l C o r r e c t i o n
W h i t e L i m i t
D i f f L e f t
D i f f R i g h t
D i f f L e f t > W h i t e D i f f A N D
D i f f R i g h t > W h i t e D i f f
Figure 5.40: Outliers correction
.
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