CHEETAH Hardware User’s Manual
Imperx, Inc.
Rev. 6.2
6421 Congress Ave.
7/7/2015
Boca Raton, FL 33487
+1 (561) 989-0006
70 of 152
2.17.2 User Defined LUT
The user can define any 12-bit to 12-bit transformation as a user LUT and can
upload it to the camera using the configuration utility software. The user can specify
a transfer function of their choice to match the camera’s dynamic range to the
scene’s dynamic range. There are no limitations to the profile of the function. The
LUT must include all possible input values (0 to 4095) – Figures 2.18.
Input signal
O
u
tp
u
t
s
ig
n
a
l
Original TF
Modified TF
Figure 2.18 – Custom LUT
2.18
DEFECTIVE PIXEL CORRECTION
A CMOS imager is composed of a two-dimensional array of light sensitive pixels. In
general, the majority of the pixels have similar sensitivity. Unfortunately, there are some
pixels which sensitivity deviates from the average pixel sensitivity. A defective pixel is
defined as a pixel whose response deviates by more than 15% from the average response.
In extreme cases these pixels can be stuck ‘black’ or stuck ‘white’ and are non-responsive
to light. There are two major types of pixel defects – “Defective” and “Hot”.
1.
”
Defective
” – these are pixels which sensitivity deviates more than 15% due to
fluctuations in the CMOS manufacturing process. During final camera testing at the
factory up to 1024 defective pixels are identified and will be automatically corrected
if defective pixel correction is enabled. Two type of defective pixels are possible:
a.
“
DARK
” is defined as a pixel, whose sensitivity is lower than the sensitivity of
the adjacent pixels. In some cases this pixel will have no response (completely
dark).
b.
“
BRIGHT
” is defined as a pixel, whose sensitivity is higher than the sensitivity
of the adjacent pixels. In some cases this pixel will have full response (completely
bright).
