CHEETAH Hardware User’s Manual
Imperx, Inc.
Rev 1.7
6421 Congress Ave.
8/26/2016
Boca Raton, FL 33487
+1 (561) 989-0006
50 of 121
factory. Both LUT’s are available for modifications, and the user can generate and upload
his own custom LUT using the CHEETAH Configuration software – refer to Appendix B.
LUT
12 bit input
data
12 bit output
data
Figure 25
: Look up table
2.13.1 Standard Gamma Correction
The image generated by the camera is normally viewed on a CRT (or LCD) display,
does not have a linear transfer function – i.e., the display brightness is not linearly
proportional to the scene brightness (as captured by the camera). As the object
brightness is lowered, the brightness of the display correspondingly lowers. At a
certain brightness level, the scene brightness decrease does not lead to a
corresponding display brightness decrease. The same is valid if the brightness is
increased. This is because the display has a nonlinear transfer function and a
brightness dynamic range much lower than the camera. The camera has a built-in
transfer function to compensate for this non-linearity, which is called gamma
correction. If enabled, the video signal is transformed by a non-linear function close
to the square root function (0.45 power) – formula 2.4. In the digital domain this is a
nonlinear conversion from 12-bit to 12-bit – Figure 26.
Output signal [V] = (input signal [V])
0.45
(2.4)
