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The image is captured by a sensor
(e.g. Camera), and digitized if the
output of the camera or sensor is not
already in digital form, using
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Components of Digital Image Processing Systems
The problem domain, such as to detect human faces in an Image.
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Two elements are required to acquire digital
First: is the physical device that is sensitive to the
energy radiated by the object we wish to image
Second: called a digitizer, is a device for converting
the output of the physical sensing device into digital
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An image sensor is a device that converts an optical image into an electronic signal.
It is used mostly in digital cameras, camera modules and other imaging devices. Early
analog sensors were video camera tube; most currently used are digital charge
coupled device (CCD) or complementary metal–oxide–semiconductor (CMOS) active
CMOS image sensorA CCD image sensor on a flexible circuit board
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Today, most digital still cameras use either a CCD image sensor or a CMOS
sensor. Both types of sensor accomplish the same task of capturing light and
converting it into electrical signals.
Each cell of a CCD image sensor is an analog device. When light strikes the
chip it is held as a small electrical charge in each photo sensor. The charges
are converted to voltage one pixel at a time as they are read from the chip.
Additional circuitry in the camera converts the voltage into digital information.
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Usually consists of the digitizer, mentioned before, plus
hardware that performs other primitive operations, such as
an arithmetic logic unit (ALU), which performs arithmetic
and logical operations in parallel on entire images.
This type of hardware sometimes is called a front-end
subsystem, and its most distinguishing characteristic is
speed. In other words, this unit performs functions that
require fast data throughputs that the typical main
computer cannot handle.
Specialized Image Processing Hardware
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• RISC vs CISC
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Multiple Instruction stream Multiple Data stream:
Several processors execute different instructions on different data.
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Single Instruction stream Multiple Data stream:
Several processors execute the same instruction on different data.
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is a set of data processing elements connected in series, where the output of
one element is the input of the next one. The elements of a pipeline are often
executed in parallel or in time-sliced fashion; in that case, some amount of
buffer storage is often inserted between elements.
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The computer in an image processing system is a
general-purpose computer and can range from a PC to a
supercomputer. In dedicated applications, sometimes
specially designed computers are used to achieve a
required level of performance.
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بحجم الصورة1024*1024بكسل(هو بكسل كل8بت)لم اذا الذكرة من ميكابايت الى تحتاج هذه
الصورة ضغط يتم
There are three different types of digital storage that are available for digital
image processing applications
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One method of providing short-term storage is computer memory.
Another is by specialized boards, called frame buffers, that store
one or more images and can be accessed rapidly.
The on-line storage method, allows virtually instantaneous image
zoom, as well as scroll (vertical shifts) and pan (horizontal shifts).
On-line storage generally takes the form of magnetic disks and
optical-media storage. The key factor characterizing on-line
storage is frequent access to the stored data.
Finally, archival storage is characterized by massive storage
requirements but infrequent need for access.
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Used for recording images, include laser
printers, film cameras, heat-sensitive devices,
inkjet units and digital units, such as optical and
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It is the algorithm that runs on your hardware to achieve specific results.
This software can be your own designed algorithm or you can just be an
end user (eg: using Photoshop).
Image Processing software
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A display device is an output device for presentation of information in visual
When the input information is supplied as an electrical signal, the display is
called an electronic display.
Common applications for electronic visual displays are televisions or
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Is almost a default function in any computer system, in
use today. Because of the large amount of data
inherent in image processing applications the key
consideration in image transmission is bandwidth.
In dedicated networks, this typically is not a problem,
but communications with remote sites via the internet
are not always as efficient.