Channel Balancing - FLIR GRASSHOPPER 3 Series Technical Reference

9.5

Channel Balancing

Some camera sensors are capable of running in a multiple output (or "multi tap") mode. In multiple output mode,
the sensor is capable of reading out data at very high speed. This allows the camera to operate at fast frame rates.
In single output mode, all pixels are shifted off the sensor to the lower left corner of the sensor. In a multiple output
mode the image is divided into sections for reading off the sensor. For example, in a dual output mode, the right
half of the horizontal CCD is reversed and is read off the sensor at the lower right, while the left half is still read off
at the lower left.
As a result of pixel data coming off the sensor at different locations, multiple analog-to-digital (A/D) converters are
required to convert the electrical charge to digital output. All A/D converters, even those of the same make/model,
will have subtle differences in the way they process the same input information. This can result in different output
data given the same input and same A/D conversion parameters. Specifically, this can result in the difference in
image intensities between the different sections of an image.
To address this issue, FLIR "balances" every multiple tap unit as part of the quality control process. This balancing
process attempts to minimize the difference in gains that result from the different A/D converters.
2/10/2017
©2013-2017
FLIR Integrated Imaging
Solutions Inc. All rights reserved.
Figure 9.2: Example of dual channel image with no balancing
Note: Some slight differences may still be visible between 0-10
dB.
Note: Balancing is only done in full resolution modes.
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