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LQ-401CL
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Fig.21 Color shading correction concept drawing
Note:
For this function, no reference value is stored in the camera.
Operating procedure for individual R, ,B and NIR channel shading correction:
1. Before making adjustment, approximately 30 minutes of warm up is required.
2. Make sure the output signal is not saturated (<80% of full output is recommended)
3. Set command PGC=2 and SDC=2.
4. Set command SDR to 1 to initiate shading correction.
5. If desired, set command PGR to 0 to activate flat-field (pixel gain) correction to
correct for pixel response non-uniformity.
6. Again set SDR=1 after running the flat-field (pixel gain) correction
Please note that before adjusting the shading, the white balance must be adjusted
.
6.2.11 Lateral chromatic aberration
This function compensates for lateral chromatic aberration of lenses. Lateral chromatic aberration
causes different line lengths for the R, G, B and NIR rays at the focal point. This function enables
compensation data for up to three lenses to be stored.
The compensation data specifies how many
pixels the R, B and NIR channels should be stretched or shortened to match the line length of the G
channel which is the reference. The range of correction is minus three pixels to plus three pixels.
In order to realize this function, the LQ-400CL uses an FIR (finite impulse response) filter for R, B
and NIR channels. The filter’s response is determined by a set of 7 types of filter coefficients. The
4096 pixels that make up a line are divided in 16 blocks, with each block having 256 pixels.
To compensate lateral chromatic aberration, the 7 types of coefficients are set for each block.
In the factory, a default set of 112 data elements (7 types x 16 blocks) are calculated and stored.
4096th Pixel
Pixel number in each block: 256 pixels
Note: Restrictions for this function
In order to adjust properly lateral chromatic aberration, the difference between G and R or B or
NIR on right and left sides should be equal. Otherwise, the compensation may not be properly
executed.
The following screen is used for creating up to three user-defined sets of lateral chromatic
aberration data in the camera control tool.