Brief Introduction to Digital Image Processing

1. - Nagashree B N
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2. • An image may be defined as a two-dimensional function, f(x, y)
where x and y are plane coordinates
• The amplitude of f at any pair of coordinates (x, y) is called the
intensity or gray level of the image at that point
• An image is called digital image when value of x, y and f are all
finite and discrete quantities
• Processing digital images by means of a digital computer is called
DIP
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3. • A digital image is composed of a finite number of elements called
pixels, each of which has a particular location and value
• f(x, y)
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Y
X

4. • Computers can operate on images including ultra-sound, electron
microscopy and computer-generated images
• Three types of image processing are:
• Low-level: Pre Processing performed such as to reduce noise,
contrast enhancement, and image sharpening (I/O are images)
• Mid-level: inputs may be images, outputs are attributes from
operations such as Segmentation, Object description &
Classification.
• High-level: Image analysis
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5. • One application of DIP was in the newspaper industry
• Pictures were first sent by submarine cable between London and
New York
• Later Bartlane cable picture transmission system was introduced
which reduced image transmission time
• DIP grew with growth of digital computer
• Applications of DIP can be found in astronomy, biology, nuclear
medicine, law enforcement, defense and industry
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6. Gamma-Ray Imaging:
• Major use of gamma ray images include nuclear medicine and
astronomical observations
• In nuclear medicine, gamma ray detector produces image by
collecting gamma rays emitted by radioactive isotopes which is
injected to a patient
• These images are used to locate sites of bone pathology, such as
infections or tumors
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7. X-Ray Imaging:
• Applications of X-Ray are:
- Used in medical diagnostics
- Used in industry to examine circuit boards for missing
components or broken traces
- Angiography
- Computerized Axial Tomography (CAT)
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8. Ultraviolet band Imaging:
• Applications of UV-Ray are:
• It is used in lithography, industrial inspection, lasers, biological
imaging and astronomical observation
• Ultraviolet light is used in fluorescence microscopy
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9. Visible and Infrared Band Imaging:
• Application area includes light microscopy, astronomy, remote
sensing, industry and law enforcement
Microwave Band Imaging:
• Its application is radar, which has ability to collect data over
virtually any region at any time, regardless of weather or ambient
lighting conditions
Radio Band Imaging:
• It is used in medicine for Magnet Resonance Imaging(MRI)
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11. • The image acquisition stage involves preprocessing, such as scaling.
• Image enhancement is the process of manipulating an image to make it
more suitable for a specific application [subjective]
• Image restoration is an area that also deals with improving the
appearance of an image [objective]
• Color image processing deals with processing color image for various
purpose
• Wavelets are the foundation for representing images in various degrees
of resolution. This representation subdivides the images into smaller
regions
• Compression deals with techniques for reducing the storage required to
save an image, or the bandwidth required to transmit it.
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12. • Morphological processing deals with tools for extracting image
components that are useful in the representation and description of
shape
• Segmentation procedures partition an image into its constituent parts
or objects.
• Representation and description (feature selection) is raw pixel data,
constituting either the boundary of a region (i.e., the set of pixels
separating one image region from another) or all the points in the
region itself.
• Recognition is the process that assigns a label to an object based on its
descriptors
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14. Sensing
• Two elements are required to acquire digital images.
i) A physical device that is sensitive to the energy radiated by the
object we wish to image.
ii) A digitizer, is a device for converting the output of the physical
sensing device into digital form
Specialized image processing hardware (front-end subsystem)
• It usually consists of the digitizer plus hardware that performs other
primitive operations
Computer
• In DIP system, computer is a general-purpose computer and can range
from a PC to a supercomputer
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15. Software
• Software for image processing consists of specialized modules that
perform specific tasks.
Mass storage capability
• It is must in image processing applications to provide adequate storage.
Categories of digital storage are:
(1) short term storage for use during processing,
(2) on-line storage for relatively fast recall,
(3) archival storage, characterized by infrequent access
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16. Image displays
• They are mainly color TV monitors. Monitors are driven by the outputs
of image and graphics display cards that are an integral part of the
computer system.
Hardcopy devices
• They are for recording images include laser printers, film cameras, heat-
sensitive devices, inkjet units, and digital units, such as optical and CD-
ROM disks
Networking
• It is almost a default function in any computer system in use today
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