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12 Pixel Data Processing
•
The black reference image must be obtained at no illumination, e.g. with lens aperture
closed or closed lens opening.
•
It may be necessary to adjust the black level offset of the camera. Ideally there should be
no grey levels at value 0 DN after adjustment of the black level offset. This is best
observed in a histogram of the black reference image.
•
Camera settings may influence the grey level. Therefore, for best results the camera
settings of the black reference image must be identical with the camera settings of the
image to be corrected.
•
The black reference image is stored in the camera by sending the command
Correction_SetBlackRef
.
There are two independent
BlackLevel
values that are activated by the setting
of
Sensor_PixelFormat
(
Mono10
/
Mono12
). Example: if
Sensor_PixelFormat
is set to
Mono10
, then setting
BlackLevel
does not alter the setting of
BlackLevel
for
Sen-
sor_PixelFormat
=
Mono12
.
12.2.3
Gain Correction
The gain correction is based on a grey reference image, which is taken at uniform illumination
to give an image with a mid grey level. The average grey level of the grey reference image
should be between 2400 and 3200 DN at 12 bit resolution (150 to 200 DN at 8 bit resolution), if
PreGain
is correctly set, so that the saturation level is at 4095 DN (@ 12 bit resolution).
Gain correction is not a trivial feature. The quality of the grey reference image
is crucial for proper gain correction.
Gain correction algorithm
After configuring the camera with a black and grey reference image, the camera is ready to
apply the gain correction:
1.
Determine the average value of the grey reference image.
2.
Subtract the offset correction matrix from the grey reference image.
3.
Divide the average value by the offset corrected grey reference image.
4.
Store the result in the camera as the gain correction matrix.
5.
During image acquisition, multiply the gain correction matrix from the offset-corrected
acquired image and interpolate the defect pixels (see Section 12.2.4).
Gain correction is not a trivial feature. The quality of the grey reference image
is crucial for proper gain correction.
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MAN093 08/2021 V1.1
Содержание MV4 Series
Страница 8: ...CONTENTS 8 of 143 MAN093 08 2021 V1 1 ...
Страница 12: ...1 Preface 12 of 143 MAN093 08 2021 V1 1 ...
Страница 16: ...3 Product Specification Figure 3 1 Photonfocus MV4 UV 10 GigE GT camera series 16 of 143 MAN093 08 2021 V1 1 ...
Страница 40: ...4 Image Acquisition 40 of 143 MAN093 08 2021 V1 1 ...
Страница 42: ...5 Exposure Control 42 of 143 MAN093 08 2021 V1 1 ...
Страница 52: ...6 Counter Timer 52 of 143 MAN093 08 2021 V1 1 ...
Страница 64: ...10 Image Format Control 64 of 143 MAN093 08 2021 V1 1 ...
Страница 66: ...11 Frame Rate 66 of 143 MAN093 08 2021 V1 1 ...
Страница 82: ...12 Pixel Data Processing 82 of 143 MAN093 08 2021 V1 1 ...
Страница 92: ...12 Pixel Data Processing 92 of 143 MAN093 08 2021 V1 1 ...
Страница 96: ...13 Precautions 96 of 143 MAN093 08 2021 V1 1 ...
Страница 120: ...16 Troubleshooting 120 of 143 MAN093 08 2021 V1 1 ...
Страница 126: ...19 Support and Repair 126 of 143 MAN093 08 2021 V1 1 ...
Страница 128: ...20 References 128 of 143 MAN093 08 2021 V1 1 ...
Страница 132: ...A Pinouts 132 of 143 MAN093 08 2021 V1 1 ...