OPERATING AND USER MANUAL QUARTZ SERIES
54
HiQ mode - Image averaging
9.3
The camera is able to average a number of images before they are output over the interface. Averaging
N images reduces the temporal noise and increases the signal to noise ratio by a factor
√
N.
The averaging of images can be enabled by command AVG.
Command format: AVGx
Command format:
AVG?
Return Message: x
Where x indicates number of images to average; 1
≤
x
≤
10, for the Q-12A65 this is 1
≤
x
≤
8.
x = 1 is the normal, non-averaged camera operation.
HDR mode - Multislope
9.4
Introduction
9.4.1.
In the camera, a high optical dynamic range can be realized by using a multiple slope feature. For high
exposures, this ensures contrast in bright part of the scene that would otherwise saturate.
The underlying principle is in varying the pixel charge capacity of the sensor in steps. This can be
done up to 2 times within one exposure time to achieve a maximum of 3 exposure slopes. This is
illustrated in the figures below.
The multislope levels Vhigh and Vlow1 in figure 9.2, correspond to pixel reset and normal ‘single slope’
sensor charge capacity respectively. The levels Vlow2 and Vlow3 are added in multislope. The red and
blue line illustrate the effect of the additional steps.
The red line represents a pixel that receives a bright illumination. The blue line represents a pixel which
is illuminated weaker. As shown in the figure, the brightly lit pixel is affected twice by the intermediate
voltage steps that effectively temporarily limit the pixel capacity. Eventually after the total exposure
time this prevents the pixel from saturating. The darker pixel is not influenced by this multiple slope
and will have a normal response.
The pixel under bright illumination in figure 1 shows parts (horizontal lines) where the charge is
constant. Basically, this is intermediate pixel saturation. The saturation comes with additional fixed
pattern for which is not corrected for in the present camera.
The levels and exposure times are programmable via a command set as described below. This feature
results in a multislope (piece wise linear) response curve. The placement of the kneepoints in this
image depends on the specific Voltage and Timing programming.
Summary of Contents for Q-2A340
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