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IEEE 802.11
A family of standards for wireless LANs. The 802.11 standard supports 1 or 2 Mbit/s transmission on the 2.4 GHz band. IEEE 802.11b supports data rates up to11 Mbit/s on the 2.4 GHz band, while 802.11g allows up to 54 Mbit/s on the 5 GHz band.

IEEE 1394

A standard for high-speed serial devices such as digital video and digital audio editing equipment, it is now used in both the Macintosh and PC computers.  It is known by industry as IEEE Standard 1394-1995, IEEE Standard for a High Performance Serial Bus.  Developed by the IEEE Microprocessor Standards Committee, the IEEE 1394 family of standards provides flexible and cost-effective ways to share real-time (isochronous) information among data-intensive applications.

IEEE 1394 connector

A type of connector that enable you to connect and disconnect high-speed serial device, an IEEE 1394 connector is usually on the back of your computer near the serial port or the parallel port.   If a device is IEEE 1394 compatible, you can connect the device to the IEEE 1394 connector while the computer is running and Windows will detect the device and inform you when it is ready for use. Similarly, you can unplug the device while the computer is running, but you should use the Add Hardware Wizard to inform Windows that you are unplugging the device.  Windows will then inform you when the device can be unplugged from the computer.  The IEEE 1394 bus is used primarily to connect high-end digital video and digital audio devices to your computer; however, some hard disks, printers, scanners, and DVD drives can also be connected to your computer using the IEEE 1394 connector.

IEEE 1394 port

It is port that supports either a 6-pin plug whose size is 11 mm by 5.4 mm or a 4-pin plug whose size is 5.35 mm by 3.45 mm.

Image file formats

It is a standardized means of organizing and storing images. This entry is about digital image formats used to store photographic and other images; Image files are composed of either pixel or vector (geometric) data that are rasterized to pixels when displayed (with few exceptions) in a vector graphic display. The pixels that compose an image are ordered as a grid (columns and rows); each pixel consists of numbers representing magnitudes of brightness and colour.  PNG, JPEG, and GIF formats are most often used to display images on the Internet.

Image file sizes

Images file sizes, expressed as the number of bytes, increases with the number of pixels composing an image, and the colour depth of the pixels, that is the greater the number of rows and columns, the greater the image resolution, and the larger the file.  Also, each pixel of an image increases in size when its colour depth increases, an 8-bit pixel (1 byte) stores 256 colours, a 24-bit pixel (3 bytes) stores 16 million colors, the latter known as true color.

Image Compression

Image compression uses algorithms to decrease the size of a file.  High resolution cameras produce large image files, ranging from hundreds of kilobytes to megabytes, per the camera's resolution and the image-storage format capacity. High resolution digital cameras record 8 megapixel (1MP = 1,000,000 pixels / 1 million) images, or more, in true colour. For example, an image recorded by an 8 MP camera; since each pixel uses 3 bytes to record true colour, the uncompressed image would occupy 24,000,000 bytes of memory—a great amount of digital storage for one image, given that cameras must record and store many images to be practical.  Faced with large file sizes, both within the camera and a storage disc, image file formats were developed to store such large images.  

Impedance

It is the total opposition that a circuit offers to the flow of alternating current or any other varying current at a particular frequency.

Impedance, High

Generally, it refers to area of 25,000 ohms or higher.

Impedance Match

It is a condition whereby the impedance of a particular circuit, cable or component is the same as the impedance of the circuit, cable or device to which it is connected.

Infrared, IR

Light that is beyond red in the color spectrum. While the light is not visible to the human eye, infrared transmitters and receivers can send and receive infrared signals.

Infrared Cut Filter Removal, ICR

An IR filter – or IR cut filter - is a color filter blocking the infrared light while passing the visible.  There are several good reasons for using an IR-cut filter. Using a color camera to achieve realistic colors in white light requires an IR-cut filter.  The color spectrum seen by the human eye is quite limited compared to the spectrum seen by a CCD camera.  Especially, in the near infrared region of the spectrum the difference in sensitivity is significant. This is important to know since many light sources, including the sun, emit infrared light.  A CCD color camera in daylight without an IR-cut filter will therefore see a significant amount of infrared light resulting in strange colors.  Another reason for using an IR-cut filter is the limited color correction for many lenses.  It is difficult to design imaging optics covering both the visible spectrum and the near infrared spectrum at the same time.  Therefore, many lenses have different depth of focus for the visible and the infrared spectrum.  Anyway, the IR-cut filter cuts away a significant amount of the overall collected light and thereby affects the sensitivity in a negative way.  In general, color cameras are one factor less sensitive compared to monochrome (depending on the CCD or CMOS chip). This is primarily due to the IR-cut filter.  This can be done with two optical techniques: absorption or reflection.  Absorptive filters are made with special optical glass that absorbs near infrared radiation.  Reflection type filters are short-pass interference filters that reflect infrared light with high efficiency.  Some reflection filters offer cut-off wavelength at 640nm (+/-10nm), and block all wavelength above this up to about 1100nm (the limit of silicon response).  Reflective filter suitable for security cameras because it allows both visible and infrared LED light to pass through.  This allows the camera to see a color image during day light and a monochrome image at night time with infrared LED illumination. 

Inputs/Outputs (I/O’s)

The digital I/Os on, for example, a network camera can be used to connect any device that can toggle between an open and a closed circuit.  If, for example, a door switch is used as an input device, opening the door could trigger the upload of video images and the sending of notification messages.  An output might, for example, be used to automatically start a siren when there is a motion detection trigger.

Input/Output (I/O) port

It is a channel through which data is transferred between a device and the microprocessor.  The port appears to the microprocessor as one or more memory addresses that it can use to send or receive data.

Integrated Device Electronics, IDE

It is a type of disk-drive interface in which the controller electronics reside on the drive itself, eliminating the need for a separate adapter card. IDE offers advantages such as look-ahead caching to increase overall performance.

Integrated Services Digital Network, ISDN

An alternative to telephone modems that allows digital transmission over ordinary telephone copper wire and other media. Home and business users can get highly graphic Web pages more quickly through ISDN adapters than through dial-up connections.

Interface

It means the region where two systems or a major and a minor system meet and interact with each other.

Interference

It is the disturbance of an electrical or electromagnetic nature that introduces undesirable responses into other electronic equipment.

Interlacing
Interlaced video is video captured at 50 pictures (known as fields) per second, of which every 2 consecutive fields (at half height) are then combined into 1 frame. Interlacing was developed many years ago for the analog TV world and is still used widely today. It provides good results when viewing motion in standard TV pictures, although there is always some degree of distortion in the image.  To view interlaced video on e.g. a computer monitor, the video must first be de-interlaced, to produce progressive video, which consists of complete images, one after the other, at 25 frames per second. See also Progressive scan.

Interlaced scanning

The way a television decodes an image – a frame is broken into two fields, odd (1, 3, 5, 7…) and even (2, 4, 6, 8…).  A television will scan 60 fields per second with 30 odd and 30 even fields created (NTSC system) (50 field/25 frames a second for PAL system).  By combining the two fields every 1/30 of a second, a frame is created thus creating 30 frames per second – a standard in television broadcasting. 

Internet

It is a worldwide network of computers. If you have access to the Internet, you can retrieve information from millions of sources, including schools, governments, businesses, and individuals.

Internet address

An address for a resource on the Internet that is used by Web browsers to locate Internet resources.  An Internet address typically starts with a protocol name, followed by the name of the organization that maintains the site; the suffix identifies the kind of organization it is. For example, the address http://www.yale.edu/ provides the following information:

http: This Web server uses the Hypertext Transfer Protocol.

www: This site is on the World Wide Web.

edu: This is an educational institution.

Internet address is also called Uniform Resource Locator (URL).

Internal Focusing

It is conventional double helicoids focusing system that requires that all lens groups be moved by the lens barrel to either the front or rear during focusing.  This mechanism is not only complicated but bulky, more so in the case of telephoto lenses where the extra physical length of the lens requires the use of a heavier gauge metal with a consequent increase in size and weight.  In addition, a change in the length of the lens when focusing results in unbalanced hand held shooting.  With IF, only the internal small lens group shifts during focusing with no change in the lens' physical length, permitting more compact, lightweight construction and a closer minimum focusing distance for telephoto lenses.  Additional benefits include faster focusing and a reduced diameter of the focusing ring due to a simplified focusing mechanism.

Internet Protocol (IP)

A routable protocol in the TCP/IP protocol suite that is responsible for IP addressing, routing, and the fragmentation and reassembly of IP packets.

Intranet

It is a network within an organization that uses Internet technologies and protocols, but is available only to certain people, such as employees of a company.  An intranet is also called a private network.

IP Address

A 32-bit address used to identify a node on an IP inter-network. Each node on the IP inter network must be assigned a unique IP address, which is made up of the network ID, plus a unique host ID. This address is typically represented with the decimal value of each octet separated by a period (for example, 192.168.7.27).  In this version of Windows, you can configure the IP address statically or dynamically through DHCP.

IP camera
The terms IP camera, network camera and Internet camera all refer to the same thing - a camera and computer combined in one unit.  It operates as stand-alone unit and only requires a connection to the network.

IP Rating

The IP Code (or International Protection Rating, sometimes also interpreted as Ingress Protection Rating) consists of the letters IP followed by two digits and an optional letter.  As defined in international standard IEC 60529, it classifies the degrees of protection provided against the intrusion of solid objects (including body parts like hands and fingers), dust, accidental contact, and water in electrical enclosures.[2] The standard aims to provide users more detailed information than vague marketing terms such as "waterproof". 

Also known as index protection, the digits ('characteristic numerals') indicate conformity with the conditions of IEC.  Where there is no protection rating with regard to one of the criteria, the digit is replaced with the letter X.  The first digit from 0~6 indicates the level of protection that the enclosure provides against access to hazardous parts (e.g., electrical conductors, moving parts) and the ingress of solid foreign objects.  Second digit from 0~8 indicates the level of protection of the equipment inside the enclosure against harmful ingress of water.  The standard defines additional letters A/B/C/D that can be appended to classify only the level of protection against access to hazardous parts by persons.  Further letters H/M/S/W can be appended to provide additional information related to the protection of the device.

IR corrected Lenses

When standard (not infrared corrected) lenses are used, infrared ray reaches the imager in a different place than the white (day) light dose. It is caused by different refractive index for different light wavelengths. Without additional adjustment picture will be unsharp during the night time (infrared illumination).  Lenses with “IR” index (stated after lens model number) are corrected in a wide wavelength range, picture will remain sharp in both daylight and IR light conditions without any additional focus adjustment. Those lenses are optically compensated for wavelengths up to 850nm, therefore usable for day/night camera with infrared illumination.

IRE

An IRE is a unit of measure used to represent the value of composite video signals on a normalized scale.  Its name is an acronym for the Institute of Radio Engineers.  A value of 100IRE is defined as the white level in a video signal, while 0IRE corresponds to the blanking level.  When the maximum video level is at 100IRE, it will fully drive a monitor to express the best image with best brightness and contrast.  This signal level can generally be achieved when shooting video in relatively bright environments.  However, as a scene darkens, the amount of light reflected off a subject and directed toward the CCD is reduced; therefore, the camera cannot generate a signal that reaches 100IRE.  It can be said that a video signal at 50IRE has only half of the brightness and contrast of a 100IRE video signal and a 30IRE signal has only 30% of the original image.

Iris
Strictly, iris diaphragm.  Device consisting of thin overlapping metal leaves pivoting outwards to form a circular opening of variable size to control light transmission through a lens.

Isolation

Usually expressed in dB, isolation is the ability of a circuit or component to reject interference.