FLIR Camera Adjustments
102-PS242-100-01
Rev110
June 2014
Page 24 of 28
Manual mode: The following three parameters are user-specified:
o
DDE Gain: ranges from 0 to 65535 for Tau 2.7 and later releases and represents the
magnitude of high-frequency boost
For gain = 0, DDE is disabled
For gain > 0, details are enhanced by gain/2048. In other words, a value of 1
represents a 1/2048 attenuation of details whereas a value of 8192 represents a
4X enhancement of details. Note that gain is also applied globally and locally to
the low frequency portion of the image, and therefore the DDE gain is relative
(therefore users are strongly discouraged from using manual DDE mode).
o
DDE threshold: ranges from 0 to 255 and represents the maximum detail magnitude that
is boosted. Details with variance exceeding the threshold are not enhanced. Details with
variance less than the thresholds are enhanced. Values greater than 255 will place the
camera in Dynamic DDE mode with a DDE index of x-255. In this case, DDE Gain and
DDE spatial threshold are adjusted dynamically.
o
DDE spatial threshold: ranges from 0 to 15, and represents the threshold of the pre-filter
(smoothing filter) applied to the signal prior to high-frequency boost. The pre-filter
prevents low-magnitude fixed-pattern noise from being amplified. Note that the DDE
spatial threshold also represents the DDE index when in automatic DDE mode.
3.0
LUT Palettes and Polarity
Another topic to discuss is the image LUT (Lookup Table). There are a number of lookup tables that
make the image colored. This is called false color, or pseudocolor. The color is not actually related to
wavelengths of light, but rather the grayscale intensity. The most useful might be the option for White
Hot and Black Hot, which is also called the polarity of the image. The Black Hot palette is a pure
inversion of the 8-bit data where zero becomes the hottest and 255 becomes the coldest. There are some
applications where a Black Hot image allows for more perceived contrast in the image. This is primarily
due to concept discussed earlier about low luminance changes.
Figure 26: White Hot
Figure 27: Black Hot
