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The most important setting is the IR Separation Matrix. This matrix is usually generated by the SensorTune application via the “IR Separation Matrix Calculation” tab, using the sensor’s data for “Dual-Band IR Filter Transmittance Data” and “IR QE Sensitivity Data”.
SensorTune outputs the matrix as an INI file as “STATE = RGBIR CCN,” followed by the space-separated 16 floating point values. This can be merged in to an existing INI file to set the plug-in matrix.
CCN is a 4x4 matrix that works like a color correction matrix, except there are four channels, R, G, B, IR, and the matrix is only intended to remove the IR intrusion into the visible light channels, and the visible light intrusion into the IR channel. For each pixel:
[RGBI_out] = [CCN] [RGBI_in]
The RGB-IR processing routine skips this step if the pixel's value is at or above to a saturation threshold. The threshold defaults to 85% of the maximum pixel value. Some pixels in a small square of Orit's image are above this threshold, and the CCN was skipped in that area. That was the artifact she was seeing. You can set the threshold to 101% to make sure every pixel gets CCN processing.
The plug-in does allow for manual adjustment of any of the 4x4 matrix entries.
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