Description of the data path
MARLIN Technical Manual
V2.4.0
82
Look-up table (LUT) and gamma function
The AVT Marlin 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 apply it 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 a LUT is the gamma LUT:
Output = (Input)
0.45
This is used with all Marlin CCD models.
It is known as compensation for the nonlinear brightness response of many
displays e.g. CRT monitors. The look-up table converts the most significant
10 bits from the digitizer to 8 bits. The gamma function is controlled by the
register F0F00818h by toggling bit 6.
Figure 40: Gamma LUT
Output = (Input)
gamma
0
50
100
150
200
250
0
200
400
600
800
1000
Input
Ou
tp
u
t
Marlin, gamma=0.45