Image Processing Reference
In-Depth Information
The energy captured by infrared sensors is focused by an optical system onto an infrared-
sensitive material mounted at the focal plane of the optics. This material converts the relected
and emited energy into electrical signals. Real-time signal processing is used to analyze the
signals for the presence of a vehicle. The sensors are mounted overhead to view approach-
ing or departing traffic. They can also be mounted in a side-looking configuration. Infrared
sensors are utilized for signal control; volume, speed, and class measurement; detection of
pedestrians in crosswalks; and transmission of traffic information to motorists.
4.4 Video Detection
Video detection is based on real-time image processing providing efficient wide-area detection
well suited for registration of incidents on roads and in tunnels. Connected to Traffic Control-
lers, the application can also be used for vehicle detection at signalized intersections where it
is difficult or expensive to install inductive loops. Video-detection systems are also considered
Video detection combines real-time image processing and computerized patern recognition
in a flexible platform; it uses a vision processor to analyze real-time changes in the image. In
this system, cameras called image sensors capture images and provide a video signal to the
vision processor. The video signal is analyzed and the results are recorded. Video image de-
tection is one of the leading alternatives to the commonly used loop detectors. It is progress-
ively being used to detect traffic intersections and interchanges. This is because video detec-
tion is often cheaper to install and maintain than inductive loop detectors at multilane inter-
sections. In addition to speed, volume, queues, and headways, it provides traffic engineers
with many other traffic characteristics, such as level of service, space mean speed, acceleration,
and density. Video detection is also more readily adaptable to changing conditions at inter-
sections (e.g., lane reassignment and temporary lane closure for work zone activities). This is
one of the biggest advantages of video image detection. It provides traffic managers with the
means to reduce congestion and improve roadway planning. Additionally, it is used to auto-
matically detect incidents in tunnels and on freeways, thus providing information to improve
emergency response times of local authorities [ 6 ] .
Through the discussion about the image-processing cameras, it is noticeable that they have
these advantages:
• Monitors multiple lanes and multiple detection zones/lane.
• Easy to add and modify detection zones.
• Rich array of data available.
• Provides wide-area detection when information gathered at one camera location can be
linked to another.
• Generally cost effective when many detection zones within the camera field-of-view or spe-
cialized data are required.
5 Image processing
Image processing is defined as a process involving the change in the natural appearance of an
image. It consists of an input and an output. The input is an image, whereas the output is a set
of characteristics related to the image, also the output may be an image.
The main aim of image processing lies in converting the image for beter human interpreta-
tion and machine perception. The operation of image processing may contain several actions
including making the images to appear sharper, removing motion blur from images, remov-
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