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4 Functionality
4.2 Pixel Response
4.2.1 Linear Response
The camera offers a linear response between input light signal and output grey level. This can
be modified by the use of LinLog
digital gain may be applied, as follows. Please see Table 3.3 for more model-dependent
information.
Black Level Adjustment
The black level is the average image value at no light intensity. It can be adjusted by the
software by changing the black level offset. Thus, the overall image gets brighter or darker.
Use a histogram to control the settings of the black level.
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4.2.2 LinLog
Overview
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The LinLog
technology from Photonfocus allows a logarithmic compression of high light
intensities inside the pixel. In contrast to the classical non-integrating logarithmic pixel, the
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LinLog
pixel is an integrating pixel with global shutter and the possibility to control the
transition between linear and logarithmic mode.
In situations involving high intrascene contrast, a compression of the upper grey level region
can be achieved with the LinLog
response. At high intensities the response changes to logarithmic compression (see Fig. 4.10).
The transition region between linear and logarithmic response can be smoothly adjusted by
software and is continuously differentiable and monotonic.
G r e y
V a l u e
1 0 0 %
0 %
Figure 4.10: Resulting LinLog2 response curve
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LinLog
is controlled by up to 4 parameters (Time1, Time2, Value1 and Value2). Value1 and Value2
correspond to the LinLog
Value1 and Value2 respectively, the stronger the compression for the high light intensities. Time1
38
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as described in the following sections. In addition, a linear
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technology. At low intensities each pixel shows a linear
L i n e a r
R e s p o n s e
V a l u e 1
V a l u e 2
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voltage that is applied to the sensor. The higher the parameters
S a t u r a t i o n
W e a k c o m p r e s s i o n
R e s u l t i n g L i n l o g
R e s p o n s e
S t r o n g c o m p r e s s i o n
L i g h t I n t e n s i t y
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