IFrame
An IFrame is a complete image frame (known as an Intra Frame) in MPEG encoding that is coded without reference to other pictures. Compression is achieved by reducing spatial redundancy in the image, but not temporal redundancy.
Image intensifier
This device is used to intensify low-level lighting conditions via light sensitive phosphor screens, and is specifically used to improve the performance of surveillance cameras in low light conditions.
Image Plane
The plane at right angles to the optical axis at the image point.
Impedance
Measured in ohms, impedance describes the input and output characteristic of an electrical system. For the best signal quality, both input and output impedances should be equal, with CCTV systems having 75-ohm impedance throughout.
Incident Light
The light that falls directly on an object.
Index of refraction
This ratio measures the angle of incidence to the angle of refraction of light, with a denser medium bending more light and having a higher index of refraction.
Infrared camera
These cameras are well suited for surveillance of low light areas or areas with no light at all. Infrared LEDs surround the lens and shine infrared light, illuminating the scene. They usually have a fixed focal length lens, and present b/w images during low light (though some offer color in the day and b/w at night).
Infrared detector
This is an alarm that uses infrared light to detect nearby movement.
Infrared illuminator
A light source working in the infrared frequency range is called an infrared illuminator.
Infrared radiation
Invisible to the human eye, this electromagnetic radiation has a wavelength of greater than 750 manometers.
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