Linea SWIR GigE Series Camera
Operational Reference
•
57
Flat Field Correction Algorithm Description
Flat Field Correction Algorithm – Method 1 (feature: flatfieldCorrectionAlgorithm) applies the
following FFC formula for correcting pixel values.
newPixelValue[x] = (sensorPixelValue[x] - FFCOffset[x]) * (FFCGain[x])
•
FCC Gain ranges from 0.0 to 3.999 with a resolution of 1/1024
•
[x] is the Flat Field Correction Pixel coordinate.
See the FlatfieldCorrectionPixelXCoordinate features.
•
newPixelValue is the pixel value after Flat Field Correction is applied.
•
sensorPixelValue is the pixel value before Flat Field Correction is applied.
•
FFCOffset is the offset coefficient value to subtract from the sensorPixelValue.
•
FFCGain is the gain coefficient value that is multiplied with the sensorPixelValue.
Important: FFCOffset and FFCGain are derived factors calculated from a number of camera
specific feature values (Invisible DFNC features). These values are meaningless to the user.
Information on the Sapera Flat Field Coefficients File
The Flat Field Coefficients File is a standard 16-bit TIFF file for both 8-bit and 12-bit acquisition
modes. If the Flat Field Calibration is performed while using a 12-bit buffer, the user Flat Field
Calibration coefficients file is applicable to both 8-bit and 12-bit acquisitions. If a Flat Field
Calibration is performed while using an 8-bit buffer, switching to 12-bit acquisition will lose
coefficients.
Important Factors about Flat Field Processing
Important: Before calibration, the Linea SWIR GigE should be powered on long enough to achieve its nominal
temperature (a minimum of 30 minutes). A low ambient temperature may increase the time required for the
camera to reach a stable internal temperature.
Important: During calibration, no other Linea SWIR GigE features should be accessed or modified.
How to do a FFC Setup
The process requires images be snapped in black and bright conditions, followed by the FFC
process.
•
If using a sheet as a white target, it must be completely free of blemishes and texture.
•
Dirt or texture will generate variating in the image and incorporate it into the calibration
coefficients of the camera. Vertical stripes are visible while imaging after the target is removed.
•
A moving target during calibration will average out any dirt or texture present.
