ALLIED Vision Technologies Guppy F-503 - Manual (Page 131)

Description of the data path
GUPPY Technical Manual V7.1.0
131
Look-up table (LUT) and gamma function
The AVT 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 camera'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 com-
pensation 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 69: LUT with gamma=0.5
Output = (Input) gamma
0
50
100
150
200
250
0 200 400 600 800 1000
Input
Ou
tp
u
t
Guppy, gamma=0.5