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Image Scanner

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What is Image Scanner?

When referring to hardware, a scanner or optical scanner is a hardware input device that optically "reads" and image and converts it into a digital signal. For example, a scanner allows a user to take a printed picture, drawing, or document and convert it into a file so that it can be stored, viewed, and edited on a computer.

In computing or computer, an image scanner is a device used to transfer images or text into a computer. There are special models for scanning photo negatives, or to scan books. In the computer, the signal from the scanner is transferred to a digital image. This image can then be edited, printed, etc. All scanners have special parts which are used to take a picture from an object. Charge-coupled device or Contact Image Sensor parts take the light from the object and change it into a digital signal. The digital signal is then transferred to the computer memory or is read in the scanner's processor. With some software it can be changed to a compressed digital image, like JPEG or PNG. Text written by hand can be changed to ASCII code by an OCR program. It is very important for computer.

 

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History of Image Scanner:-

Modern scanners are considered the successors of early telephotography and fax input devices.

The pantelegraph (Italian: pantelegrafo; French: pantelegraphe) was an early form of facsimile machine transmitting over normal telegraph lines developed by Giovanni Caselli, used commercially in the 1860s, that was the first such device to enter practical service. It used electromagnets to drive and synchronize movement of pendulums at the source and the distant location, to scan and reproduce images. It could transmit handwriting, signatures, or drawings within an area of up to 150 x 100mm.

Edouard Belin's Belin graph of 1913, scanned using a photocell and transmitted over ordinary phone lines, formed the basis for the AT&T Wire photo service. In Europe, services similar to a wire photo were called a Belin. It was used by news agencies from the 1920s to the mid-1990s, and consisted of a rotating drum with a single photodetector at a standard speed of 60 or 120 rpm. They send a linear analogy AM signal through standard telephone voice lines to receptors, which synchronously print the proportional intensity on special paper. Colour photos were sent as three separated RGB filtered images consecutively, but only for special events due to transmission costs.

 

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