ALLIED Vision Technologies Guppy PRO F-503 - Manual (Page 111)

Description of the data path
Guppy PRO Technical Manual V4.0.0
109
Look-up table (LUT) and gamma function
The AVT Guppy PRO 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 to be applied on 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 an LUT is the gamma LUT:
There is one gamma LUT (gamma= 0.45)
Output = (Input)
0.45
or with normalized values:
Output/1023 = (Input/4095)
0.45
This gamma LUT is used with all Guppy PRO models.
Gamma is known as compensation for the nonlinear brightness response of
many displays e.g. CRT monitors. The look-up table converts the incoming
12 bit from the digitizer to outgoing 10 bit.
Figure 43: LUT with gamma= 0.45
Output = f (Input)
0
200
400
600
800
1000
0 500 1000 1500 2000 2500 3000 3500 4000
Input
O
u
tput
Guppy PRO, gamma=0.45