Standard Features AW00011916000
284 Basler scout GigE
12.8.2 Lookup Table (scA750-60 Only)
On these cameras, pixel data is acquired at 10 bit depth. Before the pixel values are transmitted out
of the camera, the two least significant bits are dropped and the pixel data is transmitted at 8 bit
depth.
Normally, the 10 bit pixel data reported by the sensor’s ADCs is directly used to generate the 8 bit
output transmitted by the camera. The luminance lookup table feature lets you use a custom 10 bit
to 10 bit lookup table to map the 10 bit output reported by the ADCs to 10 bit values of your choice.
The mapped 10 bit values will then be truncated and transmitted by the camera as 8 bit values.
The lookup table is essentially just a list of 1024 values, however, not every value in the table is
actually used. If we number the values in the table from 0 through 1023, the table works like this:
The number at location 0 in the table represents the mapped 10 bit value that will be used
when the sensor reports that a pixel has a value of 0.
The number at location 1 is not used.
The number at location 2 in the table represents the mapped 10 bit value that will be used
when the sensor reports that a pixel has a value of 2.
The number at location 3 is not used.
The number at location 4 in the table represents the mapped 10 bit value that will be used
when the sensor reports that a pixel has a value of 4.
The number at location 5 is not used.
The number at location 6 in the table represents the mapped 10 bit value that will be used
when the sensor reports that a pixel has a value of 6.
And so on.
As you can see, the table does not include a mapped 10 bit output value for every pixel value that
the sensor can report. So what does the camera do when the sensor reports a pixel value that is
between two values that have a mapped 10 bit output? In this case, the camera performs a straight
line interpolation between the two nearest neighbors to determine the value that it should use. For
example, assume that the sensor reports a pixel value of 5. In this case, the camera would perform
an interpolation between the values at location 4 and location 6 in the table. The result of the
interpolation would be used as the mapped 10 bit value.
Another thing to keep in mind about the table is that location 1022 is the last location that will have
a mapped 10 bit value associated with it. If the sensor reports a pixel value of 1023, the camera will
not be able to perform an interpolation. In this case, the camera simply uses the mapped 10 bit
value from location 1022 in the table.
The advantage of the luminance lookup table feature is that it allows a user to customize the
response curve of the camera. The graphs on the next page show the effect of two typical lookup
The information in this section only applies to scA750-60 gm/gc cameras. For
information about the other camera models, see Section 12.8.1 on page 281.
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