A device that ‘scans’ images, book pages, etc.

Scanning is basically taking a close-up photograph (just very slowly and with great detail). The scanned image data is passed to the computer.

The most common type of scanner is the flat-bed scanner which has a glass plate on which the item to be scanned is placed. The item is illuminated and an image of it is captured by a moving scan ‘head’.

Scanned images can be further processed once inside the computer, e.g. OCR of printed text.
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Digital Camera

A device that captures digital photographs.

Most digital cameras do not directly input data into a computer - they store photographs on memory cards. The photographs can later be transferred to a computer.

A modern digital camera can capture 10 Megapixels or more per photograph - that’s 10,000,000 coloured dots (pixels) in every photo!
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A digital camera in fact contains a small computer that controls camera focus, stores images, etc.

The camera’s computer runs a very simple operating system (stored on ROM) and usually provides a menu-based GUI for the user.

Video Camera

A device that captures moving images, or video.

Like a digital camera, most video cameras do not directly input data into a computer – the captured movies are stored on video-tape or memory cards and later transferred to a computer.

However, there are some situations where video cameras do feed video data directly into a computer: television production and video-conferencing. In these situations the video data is required in real-time.
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Web Cam

This is a very basic video camera used to feed live video into a computer.

The video data from a web cam is low quality compared to a full video camera. However it is good enough for web chats (e.g. using a messenger application such as MSN Messenger or Skype).

Usually a web cam is clipped to the top of a monitor, but many laptops now have web cams built into the edge of the screen.
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An input device that converts sound into a signal that can be fed into a computer.

The signal from a microphone is usually analogue so, before it can be processed by a computer, it must be converted into digital data. An Analogue-to-Digital Convertor (ADC) is used for this (usually built into the computer’s sound card)
Many headphones now come with microphones to allow them to be used with chat and phone applications
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