Instruction manual
Guppy Technical ManualV7.4.0
106
Description of the data path
Look-up table (LUT) and gamma function
The Guppy camera provides one user-defined look-up table (LUT). The use of this
LUT allows any function (in the form Output = F(Input)) to be stored in the cam-
era's RAM and applied to the individual pixels of an image at run-time.
The address lines of the RAM are connected to the incoming digital data, these
in turn point to the values of functions which are calculated offline, e.g. with a
spreadsheet program.
This function needs to be loaded into the camera's RAM before use.
One example of using a LUT is the gamma LUT:
Output = (Input)
0.5
This gamma LUT is used with all Guppy CCD models. This is known as compensa-
tion for the nonlinear brightness response of many displays e.g. CRT monitors.
The look-up table converts the 10 bits from the digitizer to 8 bits.
Figure 61: LUT with gamma=0.5
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Input
Output = (Input)
gamma
Guppy, gamma=0.5