User`s manual

Spyder3 GigE Vision SG-14 Monochrome Cameras User’s Manual 49
Teledyne DALSA 03-032-20123-01
Set Analog Offset (Black Level)
Sets the analog offset. The analog offset should be set so that it is at least 3 times the rms noise value at
the current gain. The analog offset is configured for the noise at the maximum specified gain and as a
result you should not need to adjust the analog offset.
The Black Level Selector parameter selects which tap is selected: All, Tap1, or Tap2. Followed by using
the Black Level (DN) feature to select an offset value in a range from 0 to 255 DN (12 bit LSB).
Update Analog Gain Reference
The Update Gain Reference feature sets the current analog gain setting to be the 0 dB point. This is
useful after tap gain matching allowing you to change the gain on all taps by the same amount.
Calibrate the Camera to Remove Non-Uniformity
(Flat Field Correction)
Calibration Overview
When a camera images a uniformly lit field, ideally, all of the pixels will have the same gray value.
However, in practice, this is rarely the case (see example below) as a number of factors can contribute to
gray scale non-uniformity in an image: Lighting non-uniformities and lens distortion, PRNU (pixel
response non-uniformity) in the imager, FPN (fixed pattern noise) in the imager, etc.
Figure 25. Image with non-uniformities
By calibrating the camera you can eliminate the small gain difference between pixels and compensate for
light distortion. This calibration employs a two-point correction that is applied to the raw value of each
pixel so that non-uniformities are flattened out. The response of each pixel will appear to be virtually
identical to that of all the other pixels of the sensor for an equal amount of exposure.