Tài liệu về scanner pdf

Scanner
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Ngô Thùy Trang
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Nguyễn Ngọc Tiến
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Trần Thị Thùy Hương
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Lê Việt Tiên
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Phạm Thị Như Quỳnh
What is scanner?
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An input device that scans (reads) the
image as a series of dots and introduces
the information into the computer’s
memory.
(Infotech Glossary)
Some definition
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DPI
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Electronic code
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Digitized image
DPI
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DPI (dots per inch):
density of computer
or printer image: a
measure of the

density of the image
produced by a
computer screen or
printer.
(Prodic Dictionary)
Electronic code
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A scanner ‘see’ images and converts the
printed text or pictures into electronic
codes that can be understood by the
computer.
Electronic code
Digitized image
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A representation of a two-dimensional
image using ones and zeros (binary).
What is inside a scanner?
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Colored filter
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Rotating lamps
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Software for scanner
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OCR software
Rotating lamps
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The scanner operates by using 3 rotating
lamps which has a different colored filter
Colored filter

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It has 3 different colors: red, green and blue
Software for scanner
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Software for scanner translates the API
procedure calls into primitive commands
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Some common scanner software:
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SANE (Scanner Access Now Easy)
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TWAIN
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ISIS (Image and Scanner Interface Specification)
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WIA (Windows Image Acquisition)
(Wikipedia)
OCR software
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OCR (Optical Character Recognition)
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OCR software let you easily convert
images, such as digital photographs,
scanned documents, printed books, etc.
into text.
Flatbed scanner
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A scanner with a glass scanning surface
on which objects are placed; similar to a
photocopier. (Infotech Glossary)

How a flatbed scanner works?
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1: a flatbed scanner ‘see’ images and
converts them into electronic codes.
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2: The scanning unit moves across the
image to be scanned
How a flatbed scanner works?
Process of scanning
a glass
pane
(platen)
a bright light
Charge-
Coupled
Devices
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3: It reads the image as a series of dots
and then generates the digitized image.
How a flatbed scanner works?
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4: Digitized image is sent to computer
and stored as a file.
How a flatbed scanner works?
You place a drawing, photograph or
other printed document face down on
the glass and close or lower the plastic
cover. When you activate the scan
feature, a light shines from under the
plastic and a copy of your paper appears

on your monitor.
Uses of Flatbed scanner
Thank you for your attention!