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accommodate scenes with small temperature range differences or
scenes with very large temperature range differences. IR Gain should
be set to extract the detail needed from the scene. IR gain can be
adjusted manually or automatically.
3.12.2.1 Auto-Gain
When the camera is in Auto-Gain it will automatically invoke the Auto-
Level mode. The Auto-Gain mode will then automatically adjust the gain
to give maximum contrast in the display. The Auto-Gain mode will also
adjust the Gain setting dynamically as the scene conditions change to
maintain maximum contrast. Auto-Gain adjusts the gain of the IR
camera automatically and is the preferred setting.
3.12.2.2 IR Gain Control
This is the manual gain adjustment to compensate for scenes with
large or small temperature differences. When in manual gain
mode the symbol appears in the left middle of the display monitor.
The GAIN control varies the thermal sensitivity of the imager; that
is, the span of temperatures the imager is able to discriminate over
the full gray scale of the display. Increasing gain increases the
imager sensitivity, allowing temperature discrimination over a
narrower span of temperatures (i.e. small temperature differences
are shown as different shades of gray). Decreasing gain
decreases the sensitivity for discrimination over a wider span of
temperatures, giving a wider dynamic range.
3.12.3 Examples of Level and Gain
The IR camera’s image is made up of hundreds of distinct shades of
gray, ranging from black to white. The gain and level settings determine
how temperature differences in the scene are mapped into the gray scale
of the image. The level setting will adjust where the temperature scale is
centered. The gain setting will adjust how wide a temperature difference
will be represented by a ‘full scale’ (that is, a full black to full white)
change in the image (Figure 3-38).
3.13 Operating the IR Camera
Unless otherwise noted, refer to Figure 3-1 for IR camera operation.
a. Press the CCD-IR Switch to select the IR camera. The image on the
display will show which camera is selected.
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