Catalogue Security Technology

What means......?
AES
Auto Electronic Shutter
Normally, the CCD chip in video cameras is exposed for 1/50th of a second and then
read out. Since CCDs are very sensitive to light, the sensor would quickly be overexposed
in strong light and the output signal rendered unusable. Therefore, either
the amount of light to the sensor must be reduced by a shutter in the lens or the
exposure time of the sensor reduced. The electronic shutter shortens the effective
exposure time of the CCD up to 1/100,000th of a second
AGC
Automatic Gain Control
In contrast to a shutter, the automatic gain control is active in poor lighting conditions.
A control voltage is obtained from the image which controls the CCD signal
gain depending on the brightness level so as to provide a constant video signal on
the monitor. A negative aspect is that the CCD noise is amplified with increasing
gain, which is where AGC has its limitations.
For some applications, it may be necessary to deactivate the automatic gain control,
for example, small bright objects on a dark background (astronomy). In this case,
the AGC would greatly intensify the relatively dark image and overamplify the small
bright object.
BLC
Back Light Compensation
Where there are strong contrasts, for example, a bright background or bright window
in the visual field of a camera, other objects are often difficult to distinguish.
The BLC can reduce this effect.
DNR
Digital Noise Reduction
This function effectively suppresses image noise which occurs in poor lighting
conditions. Noise reduction generally takes place in that the signal processor in the
camera places several individual images one on top of the other. This reduces the
image noise and amplifies the image information, however rapid movements can
look slightly blurred or fuzzy in the image.
DSP
Digital Signal Processor
These cameras use a digital signal processor to internally process the signals from
the CCD chip. The presence of such a DSP generally says little about a camera‘s
performance. Decisive are the computing capacity (speed) of the DSP and programming.
The performance of DSPs is measured in MIPS (Million Instructions Per
Second).
WDR
Wide Dynamic Range
The wide dynamic function allows the display of image contents with strongly
varying brightness levels. Conventional CCD cameras have a linear dynamic range
and therefore do not have the same level of perception as the human eye, which
can recognise contrast levels as high as 1000:1. Humans therefore can be in a room
with an illumination level of 100 lux, for example, and see through a window with an
illumination level of 100,000 lux at the same time.
In surveillance practice, there are often situations where observations are made with
strong differences in contrast (for example, cars driving with full beam at night). WDR
cameras use a technology by means of which they store images with different exposure
times for the light and dark areas in their memory. A high-performance DSP is
able to generate from these images an image with a much higher dynamic range.
AI
Auto Iris
These cameras offer the possibility to connect auto iris lenses. With these types of
lenses, the electronic shutter of the camera is switched off and the brightness controlled
by an electromechanically operated shutter. Distinction is made here between
lenses that automatically obtain their control voltage directly from the video signal
of the camera (video drive) or lenses that only have an electromechanical shutter
drive (DC drive). In the case of the latter, the control voltage is generated in the camera.
A special connector is provided on the camera body for electrical connection
to the lens. To be noted is that the pin assignments of this connector differ with both
types of lenses.
DC
Connector for DC Drive Lenses
For cameras with this option, DC controlled auto iris lenses can be used. In the case
of these lenses, the shutter is controlled electromechanically by the camera. The
background brightness is adjusted with a control on the camera.
C/CS-Mount
C/CS-Mount Lens Thread
This is a standard lens mounting thread. These screw threads have a diameter of
1 inch (25.4 mm) and a pitch of 1/32 inch (0.79 mm). The difference between a C and
CS-mount is the flange focal length, i.e. the distance from the mounting flange to
the imaging plane (CCD sensor). For a C-mount this is 17.52 mm and for a CS-mount
12.52 mm. Our cameras all have a CS-mount flange focal length; C-mount lenses can
be mounted with a 5 mm thick extension tube (included).
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