Lookup Table - Basler A102f User Manual

6.7.8 Lookup Table

The A102 camera has a sensor that reads pixel values at a 12 bit depth, however, the camera can
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be set to output pixel values at an 8 bit depth. When set for 8 bit output, the camera normally uses
an internal process to convert the 12 bit pixel values from the sensor to the 8 bit values transmitted
out of the camera. A102
lookup table to map the 12 bit sensor output to 8 bit camera output rather than using the internal
process.
The lookup table is essentially just a list of 4096 values, however, not every value is the table is
actually used. If we number the values in the table from 0 through 4095, the table works like this:
• The number at location 0 in the table represents the 8 bit value that will be transmitted out of
the camera when the sensor reports that a pixel has a value of 0.
• The numbers at locations 1 through 7 are not used.
• The number at location 8 in the table represents the 8 bit value that will be transmitted out of
the camera when the sensor reports that a pixel has a value of 8.
• The numbers at locations 9 through 15 are not used.
• The number at location 16 in the table represents the 8 bit value that will be transmitted out of
the camera when the sensor reports that a pixel has a value of 16.
• The numbers at locations 17 through 23 are not used.
• The number at location 24 in the table represents the 8 bit value that will be transmitted out of
the camera when the sensor reports that a pixel has a value of 24.
• And so on.
As you can see, the table does not include an 8 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 defined 8 bit output? In this case, the camera performs a straight
line interpolation to determine the 8 bit value that it should transmit. For example, assume that the
sensor reports a pixel value of 12. In this case, the camera would perform a straight line
interpolation between the values at location 8 and location 16 in the table. The result of the
interpolation would be reported out of the camera at an 8 bit depth.
Another thing to keep in mind about the table is that location 4088 is the last location that will have
a usable 8 bit value associated with it. (Locations 4089 to 4095 are not used.) If the sensor reports
a value above 4088, the camera will not be able to perform an interpolation. In cases where the
sensor reports a value above 4088, the camera simply transmits the 8 bit value from location 4088
in the table.
Please look at page
table smart feature. You will notice that the first two quadlets of the register include bits that allow
you to check for this feature's presence and to enable or disable the feature. These initial two
quadlets are followed by 4096 quadlets. The 4096 quadlets contain the values that make up the
customized lookup table.
BASLER A102
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DRAFT
cameras also include a smart feature that allows you to use a custom
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6-25 and examine the layout of the control and status register for the lookup
Smart Features
6-23