User`s manual

Preliminary
58 • Operational Reference Genie Monochrome Series-GigE Vision Camera
Flat Field (Image Shading) Correction
Image Shading correction, also know as 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 Genie camera stores flat field correction data until power off or in its user setting state for
recall at any time (see "
Power-up Configuration" on page 30). Flat field correction data is composed of
8 bit gain and 8 bit offset coefficients
The CamExpert Flat Field Correction tool allows calibrating. saving, and loading the flat field
calibration data for any Genie camera being controlled.
Before performing calibration, verify Genie 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. Note the lens iris position for a white but not saturated image.
Additionally check that the lens iris closes well or have a lens cover to grab the dark calibration image.
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 Genie. Each sensor 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:
Pre-processing • 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 Genie used. To aid in determining if the reference
images are valid, a histogram tool is provided so that the user can review the images used for the
correction data.