Teledyne Princeton Instruments PI-MTE, System Manual

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54 PI-MTE System Manual Issue 6
5.5.2 Binning
Binning is the process of adding the data from adjacent pixels together to form a single
pixel (sometimes called a super pixel), and it can be accomplished in either hardware or
software. Rectangular groups of pixels of any size may be binned together, subject to
some hardware and software limitations.
5.5.2.1 Hardware Binning
Hardware binning is performed on the CCD array before the signal is read out of the
output amplifier. For signal levels that are readout noise limited this method improves
S/N ratio linearly with the number of pixels grouped together. For signals large enough
to render the camera photon shot noise limited, the S/N ratio improvement is roughly
proportional to the square root of the number of pixels binned.
Binning also reduces readout time and the burden on computer memory, but at the
expense of resolution. Since shift register pixels typically hold only twice as much
charge as image pixels, the binning of large sections may result in saturation and
“blooming”, or spilling of charge back into the image area.
Figure 5-7 illustrates an example of 2 x 2 binning. Each pixel of the image displayed by
the software represents 4 pixels of the CCD array. Rectangular bins of any size are
possible.
Figure 5-7: 2 x 2 Binning for Images
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