Ranger HRC™ operator´s manual – Functions and features
Publ. No. TM 614 006 699 Rev B – ENGLISH (EN) – Oct 30. 2008
5.2
IR image optimization
The quality of the IR image depends on many factors, such as target tem
-
perature, ambient temperature, distance to target, etc. The IR Camera
has a number of functions – automatic and manual – that are used to
control the image quality.
5.2.1
NonUniformity Correction
Non-Uniformity Correction (NUC) is a function that performs an internal
calibration of the IR camera.
NUC can be performed in three different ways. With Internal NUC, the
image is calibrated against a shutter inside the camera (Internal shutter).
With External NUC, either the lens cover (External shutter) or the scene
(Shutter off) is used as thermal reference.
The normal procedure is to start with an Internal NUC. If an acceptable
image quality is not achieved, an External NUC against the lens cover or
against the scene may improve the image.
At startup of the system, NUC has to be performed frequently (every 5
minutes) as the temperature of the IR Camera changes. After about
30 minutes, NUC is only needed when the quality of the image is
degenerated.
5.2.2
Adjustment area
The IR Camera automatically adjusts the image based on the scene con-
tents. By selecting different adjustment areas, it is possible to control
which part of the scene that shall be used when adjusting the image.
The selected area has an impact on the adjustments of level (brightness),
span (contrast) and color distribution, as illustrated in the figures below.
