23
Day and night cameras are useful in environments that restrict the use of artificial light. They
include low-light video surveillance situations, covert surveillance and discreet applications, for
example, in a traffic surveillance situation where bright lights would disturb drivers at night.
An IR illuminator that provides near-infrared light can also be used in conjunction with a day
and night camera to further enhance the camera’s ability to produce high-quality video in low-
light or nighttime conditions.
For more information on IR illuminators, visit Axis’ website at
www.axis.com/products/cam_irillum
Figure 2.3c At left, image without an IR illuminator; at right, image with an IR illuminator.
2.4
Megapixel network cameras
Megapixel network cameras, available in Axis’ fixed cameras and fixed dome cameras, incorpo-
rate a megapixel image sensor to deliver images with one million or more pixels. This is at least
two times better pixel resolution than what can be provided by analog cameras.
A megapixel, fixed network camera can be used in one of two ways: it can enable viewers to see
greater details in a higher resolution image, which would be helpful in identifying people and
objects, or it can be used to cover a larger part of a scene if the image resolution is kept the
same as a non-megapixel camera.
Megapixel cameras today are normally less light sensitive than a non-megapixel network
camera. The higher-resolution video streams generated by a megapixel camera also put higher
demands on the network bandwidth and storage space for recordings, although this can be
mitigated by using the H.264 video compression standard.
For more on H.264 , see Chapter 7.
NETWORk CAMERAS - CHAPTER 2
