Photon Focus MV8-D8424-G01-GT, User Manual, Page: 71 / 139

11.4 Gain and Offset
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 11.3.3.
It is recommended to do the calibration without a lens. The quality of the grey
reference image is crucial for proper Bad Pixel Correction.
11.3.3 Storing the calibration in permanent memory
After running the calibration procedure (see Section 11.3.2) the calibration values are stored in
RAM. When the camera is turned off, their values are lost.
To prevent this, the calibration values must be stored in flash memory. This can be done by
clicking on the property
BadPixelCorrection_SaveToFlash (in category BadPixelCorrection ). Wait
until the command has been finished.
Storing the calibration in permanent memory overwrites the factory calibration.
11.4 Gain and Offset
There are three different gain settings on the camera:
Analog Gain
Analog gain on the image sensor. Available values: x1.375, x4.0, x8.0 and x16.0.
Note that
Digital Offset
is applied after the
Analog Gain
.
Gain (Digital Fine Gain)
Digital fine gain accepts fractional values from 0.01 up to 15.99. It is
implemented as a multiplication operation. Colour camera models only: There is
additionally a gain for every RGB colour channel. The RGB channel gain is used to
calibrate the white balance in an image, which has to be set according to the current
lighting condition.
Digital Gain Digital Gain is a coarse gain with the settings x1, x2, x4 and x8. It is implemented
as a binary shift of the image data where ’0’ is shifted to the LSB’s of the gray values. E.g.
for gain x2, the output value is shifted by 1 and bit 0 is set to ’0’.
The resulting gain is the product of the three gain values, which means that the image data is
multiplied in the camera by this factor.
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