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Scanners

In reference to computers a scanner is generally a flatbed device that can analyse text and images from a piece of paper and convert this into a digital image a computer can output (normally to image formats like JPEG, GIF, TIFF, Bitmap, and PNG). The image below shows a typical scanner, this is the desktop/flatbed variation scanner, the only other variation to sell in commercial quantity was the handheld scanner. The disadvantage with hand-held's was the low quality of the scanned image, so their popularity was short lived.

- Flatbed - Handheld

Both variations use the same CCD (charge-coupled device) or CIS (Contact Image Sensor) image sensor technology to scan documents. The image sensor in a scanner whether CCD or CIS typically reads a document by the use of a red, green and blue (RGB) data array .There are other kinds of image sensors but these are rarely used in scanners available to the general consumer. The colour depth scanned by most modern scanners is usually at least 24 bits. The other way to measure the quality a scanner can copy an image is the levels of pixels per inch (ppi).