X64 Xcelera-HS PX8 User's Manual
CamExpert Quick Start
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Flat Field Correction Calibration Procedure
Calibration is the process of taking two reference images, one of a black field – one of a light gray
field (not saturated), to generate correction data for images captured by the camera. Each camera
pixel data is modified by the correction factor generated by the calibration process, so that each
pixel now has an identical response to the same illumination.
Start the Flat Field calibration tool via the CamExpert menu bar:
Tools • Flat Field Correction • Calibration.
Flat Field Calibration Window
The Flat Field calibration window provides a three-step process to acquire two reference images
and then save the flat field correction data for the camera used. To aid in determining if the
reference images are valid, use the histogram tool to review the images used for the correction
data.
Figure 16: Flat Field – Calibration Application
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Setup the camera to capture a uniform black image. Black paper with no illumination and
the camera lens’ iris closed to minimum can provide such a black image.
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Click on Acquire Black Image. The flat field demo will grab a video frame, analyze the
pixel gray level spread, and present the statistics. The desired black reference image should
have pixel values less than 20. If acceptable, accept the image as the black reference.
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Setup the camera to acquire a uniform white image (but not saturated white). Even
illumination on white paper is acceptable, to provide a gray level of 128 minimum. It is
preferable to prepare for the white level calibration before the calibration procedure as
described in the previous section.
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Click on Acquire White Image. The flat field demo will grab a video frame, analyze the
pixel gray level spread, and present the statistics. The captured gray level for all pixels
should be greater than 128. If acceptable, accept the image as the white reference.
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Click on Save. The flat field correction data, saved as a TIF image, is given a file name of
your choice (such as camera name and serial number).
