Figure C-2 Typical Ccd Spectral Response With Magenta, Green, Cyan And Yellow Pixel Filters; Figure C-3 Cie 1931 Luminosity Curve - Honeywell ACUIX User Manual

Document 800-05662V1 Rev A
04/11
ACUIX™ PTZ High Speed Analog Dome Installation and Configuration Guide
Spectral Response and How it Relates to
NightShot/TDN
The silicon video image sensors used in CCTV cameras are sensitive to visible
light and near infrared (IR) light.
response of a CCD video image sensor extends from blue at 400 nm through red
at 700 nm to the near IR at 1000 nm. The IR cut filter limits the spectral response
of the CCD to the visible light range from 400 nm to 700 nm and gives the CCD
response the approximate shape of the photoptic spectral response of the
human eye to well-lit scenes as shown in
produce pictures with natural colors as seen by the human eye.
The apparent sensitivity of the CCD can be increased by allowing IR light to
reach it, assuming that there is IR light coming from the scene. However, this IR
light distorts the colors in the scene. Therefore, when the IR cut filter is removed
the color information is also removed from the video signal, thus producing a
monochrome or black and white video image, often referred to as night mode.
Likewise, when the IR cut filter is in place and the color information is allowed to
remain in the video signal it is usually referred to as day mode. The automatic
control of the transition between day mode and night mode is called auto
NightShot or auto True Day/Night (TDN) by most CCTV equipment
manufacturers.
Figure C-2 Typical CCD Spectral Response with Magenta, Green, Cyan and
Yellow Pixel Filters
Figure C-3 CIE 1931 Luminosity Curve
Figure C-2 shows that the typical spectral
Figure C-3. This enables the camera to
99