3—Basic Operation of the Tau and GUI Tau User’s Manual
3-16 April 2009 TAU-0035-00-10, version 100
Polarity/LUT: The Tau camera detects and
images the temperatures in a given scene. Within the
camera, these temperatures are mapped (as
determined by the AGC algorithm selected) to a range
of 0 to 256 values. In a black and white display mode,
this range is converted to shades of grey with, for
example, 0 being totally black and 256 being totally
white. The 0 to 256 grayshades range sensed is
referenced to a Look-Up Table (LUT) permanently
stored in the camera to convert the scene to a video
image. Different LUTs are available to change the
appearance of the displayed image. The most common
selection is either White Hot (hotter objects appear
brighter than cooler objects in the video display) or
Black Hot (hotter objects appear darker than cooler objects). Since the difference between
these two modes simply reverses the choice of darker or lighter for temperature extremes, this
is sometimes referred to as Polarity. Other color LUTs are available as shown below.
Figure 3-7 shows each of the LUTs as displayed in Test Pattern Ramp Mode starting with the
upper left: White Hot, Black Hot, Fusion, Rainbow, Globow, Ironbow1, Ironbow2, Sepia, Color1,
Color2, Ice Fire and Rain. Select one of these LUTs from the pull-down menu to view your image
displayed using the LUT you choose.
Simple experimentation with this feature while viewing the video image will give you familiarity.
Remember that you must click the Save Settings button on the Setup tab to save the LUT
settings as default at power-up.
Note
The setting of the Polarity/LUT mode will not affect the digital data output.
White Hot
Color1
Globow
Black Hot Fusion Rainbow
Ironbow1 Ironbow2 Sepia
Color2 Ice Fire Rain
Figure 3-7: Look-Up Table Options
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