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5.6 Bad Pixel Correction
5.6
Bad Pixel Correction
The Bad Pixel Correction corrects single pixel defects of the image sensor. If a pixel is marked as
"bad" (defect) then its value is replaced by the mean of the two neighbouring pixels on the
same image row.
5.6.1
Enable / Disable the Bad Pixel Correction
The Bad Pixel Correction can be enabled or disabled with the property
BadPixelCorrection_Enable
(in category
Correction
/
BadPixelCorrection
). By default the correction
is enabled.
5.6.2
Calibration of the Bad Pixel Correction
The calibration of the Bad Pixel Correction is based on a grey reference image, which is taken
at uniform illumination to give an image with a mid grey level. The Bad Pixel Correction is
calibrated in the production of the camera. More defect pixels may appear due to normal
aging of the image sensor. It is possible to recalibrate the Bad Pixel Correction with the
following instructions:
1.
Setup the camera to the mode where it will be usually used. (Exposure time, ...). The
width and height should be set to its maximal value.
If different exposure times will be used, calibrate the camera under the longest
exposure time.
2.
Put the camera in free-running mode by setting the property
TriggerMode
to
Off
.
3.
Start grabbing of the camera by clicking on the
Play
button.
4.
Wait until the camera has achieved working temperature.
5.
The image sensor must be uniformly illuminated to give an image with a mid grey level.
Check this before you proceed with the instructions.
6.
Set the visibility of the Device Control window of the PF_GEVPlayer to
Expert
.
7.
Every pixel that is above the higher threshold or below the lower threshold is marked as a
bad (defect) pixel. The values of these thresholds can be set by the properties
BadPixelCorrection_LowThreshold
and
BadPixelCorrection_HighThreshold
. These values must
match with acquired image used for calibration: only defect pixels should have a value
below
BadPixelCorrection_LowThreshold
or above
BadPixelCorrection_HighThreshold
. The
image could be saved to a file and viewed with an image viewer that has the ability to
show the histogram of the image as a list. A free tool with this feature is ImageJ. In the list
of histogram values check that there are only a few pixels above or below the thresholds.
8.
Run the command
BadPixelCorrection_Calculate
(category
BadPixelCorrection
) by clicking
on the corresponding button. The camera transmits a test image during calibration.
9.
The Bad Pixel Correction is now calibrated. The calibration values are stored in the
camera’s RAM and these values are lost when the camera power is turned off. To store the
calibration values to permanent memory see Section 5.6.3.
It is recommended to do the calibration without a lens. The quality of the grey
reference image is crucial for proper Bad Pixel Correction.
MAN069 12/2018 V1.1
61 of 123
Summary of Contents for MV1-D4096 Series
Page 1: ...Photonfocus MV1 D4096 Camera Series CMOS camera with GigE interface MAN069 12 2018 V1 1 ...
Page 10: ...1 Preface 10 of 123 MAN069 12 2018 V1 1 ...
Page 12: ...2 Introduction 12 of 123 MAN069 12 2018 V1 1 ...
Page 32: ...4 Product Specification 32 of 123 MAN069 12 2018 V1 1 ...
Page 94: ...6 Hardware Interface 94 of 123 MAN069 12 2018 V1 1 ...
Page 108: ...7 Software 108 of 123 MAN069 12 2018 V1 1 ...
Page 110: ...8 Mechanical Considerations 110 of 123 MAN069 12 2018 V1 1 ...
Page 112: ...9 Troubleshooting 112 of 123 MAN069 12 2018 V1 1 ...
Page 118: ...12 Support and Repair 118 of 123 MAN069 12 2018 V1 1 ...
Page 120: ...13 References 120 of 123 MAN069 12 2018 V1 1 ...
Page 124: ...B Camera Revisions 124 of 123 MAN069 12 2018 V1 1 ...