Xtium2-CL MX4 User's Manual
CamExpert Quick Start
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Using the Flat Field Correction Tool
Flat Field Correction is the process of eliminating small gain differences between pixels in a sensor
array. That sensor when exposed to a uniformly lit field will have no gray level differences between
pixels when calibrated flat field correction is applied to the image. The CamExpert Flat Field tool
functions with hardware supporting flat field processing.
Xtium2-CL MX4
Flat Field Support
The Xtium2-CL MX4
supports hardware based real-time Flat Field Correction when used with a
monochrome video source. The Xtium2-CL MX4 supports two methods for pixel replacement:
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Neighborhood Replacement: a bad pixel is replaced with the average of its 2 neighbors on the
same video line.
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3x2 Cluster Replacement: a bad pixel is replaced with the average of its 5 neighbors, its two
line neighbors and the 3 pixel neighbors from the line above. Support for this feature using
Sapera Classes and CamExpert will be available in Sapera LT 8.20, therefore contact Teledyne
DALSA Technical Support for any inquiry regarding this feature. Note that this process requires
a cluster map file defining bad pixels, provided by the camera manufacturer.
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Note that the MX4 Flat Field algorithm handles all cases of bad pixels being on the frame edge
or where neighboring pixels are also bad.
Loading the Required Camera File
Select the required camera configuration file for the connected camera. Verify the acquisition with
the live grab function. Make camera adjustments to get good images.
Set up Dark and Bright Acquisitions with the Histogram Tool
Before performing calibration, verify the acquisition with a live grab. Also at this time make
preparations to grab a flat light gray level image, required for the calibration, such as a clean
evenly lighted white wall or non-glossy paper with the lens slightly out of focus. Ideally a controlled
diffused light source aimed directly at the lens should be used. Note the lens iris position for a
bright but not saturated image. Additionally check that the lens iris closes well or have a lens cover
to grab the dark calibration image.
Verify a Dark Acquisition
Close the camera lens iris and cover the lens with a lens cap. Using CamExpert, click on the grab
button and then the histogram button. The following figure shows a typical histogram for a very
dark image (8-bit acquisition).
