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154 • Operational Reference Nano Series GigE Vision Camera
Lookup Table (LUT) Overview
The Genie Nano cameras include a user programmable LUT table as a component of its embedded
processing features. A LUT is used for operations such as gamma adjustments invert and threshold
processes.
The camera LUT table are dependent on the sensor (per pixel – see feature LUT Size) and is
illustrated in the following figure (see Processing path bits per pixel). Pixel data from the sensor is
passed through the LUT memory array, where the new programmed pixel value is then passed to
the Genie output circuit. The LUT data table is stored along with other parameters with the user
configuration function.
. . . . . .
0
1
2
3
1020
1023
1022
1021
1023
1022
1021
1020
2
1
0
3
Output
Sensor
Pixel
Data
Simplified Nano LUT Block Diagram
(10-bit example)
LUT Programmed
as Invert Function
Simplified Example 10-bit LUT Block Diagram
LUT Size vs. Output Pixel Format
The LUT size will be the same as the camera’s sensor pixel size. All camera processing is performed
at the sensor pixel format of the camera, while the user chooses the output pixel format (such as
8-bit).
Using the example of a 10-bit Nano camera, the LUT table is also 10-bit. The Nano default neutral
LUT programming is as follows:
•
When the Output Pixel format = 10-bit, the default LUT data value is equal to the LUT
index value for each index. This is a linear LUT that does not modify the sensor data.
•
When the Output Pixel format = 8-bit, the default LUT data is programmed to map the
1024 sensor pixel values to 256 output values. Therefore LUT index “0 to 3” have the value
“0”, LUT index “4 to 7” have the value “1”, and so on until the last group where LUT index
“1020 to 1023” have the value “255”.
LUT data is selected either as a predefined gamma correction, or is programmed with individual
values for various LUT index entries, or a user LUT data file is upload using the File Access controls.
Refer to the Sapera documentation for information about the SapLut Class. Note that a SapLut file
can be uploaded to the Nano but cannot be read back.