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Digital Image - Computer Graphics and Image Processing - Lecture Slides, Slides of Computer Graphics

Main points of this lecture are: Digital Image, Common Image Formats, Digital Image Processing, High-Level Processes, Early Digital Image, Bartlane System, Apollo Landings, Invention of Tomography, Computerised Axial Tomography, Image Enhancement

Typology: Slides

2012/2013

Uploaded on 04/23/2013

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What is a Digital Image?
A digital image is a representation of a two-
dimensional image as a finite set of digital
values, called picture elements or pixels
Images taken from Gonzalez & Woods, Digital Image Processing (2002)
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Download Digital Image - Computer Graphics and Image Processing - Lecture Slides and more Slides Computer Graphics in PDF only on Docsity!

What is a Digital Image?

  • A digital image is a representation of a two- dimensional image as a finite set of digital values, called picture elements or pixels

Images taken from Gonzalez & Woods, Digital Image Processing (2002) Docsity.com

What is a Digital Image? (cont…)

  • Pixel values typically represent gray levels, colours, heights, opacities etc
  • Remember digitization implies that a digital image is an approximation of a real scene

1 pixel

Images taken from Gonzalez & Woods, Digital Image Processing (2002) Docsity.com

What is Digital Image Processing?

  • Digital image processing focuses on two major tasks
    • Improvement of pictorial information for human interpretation
    • Processing of image data for storage, transmission and representation for autonomous machine perception
  • Some argument about where image processing ends and fields such as image analysis and computer vision start

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What is DIP? (cont…)

  • The continuum from image processing to computer vision can be broken up into low-, mid- and high-level processes Low Level Process Input: Image Output: Image Examples: Noise removal, image sharpening

Mid Level Process Input: Image Output: Attributes Examples: Object recognition, segmentation

High Level Process Input: Attributes Output: Understanding Examples: Scene understanding, autonomous navigation

In this course we will stop here Docsity.com

History of DIP (cont…)

  • Mid to late 1920s: Improvements to the Bartlane system resulted in higher quality images
    • New reproduction processes based on photographic techniques
    • Increased number of tones in reproduced images

Improved digital image Early 15 tone digital image

Images taken from Gonzalez & Woods, Digital Image Processing (2002) Docsity.com

History of DIP (cont…)

  • 1960s: Improvements in computing technology and the onset of the space race led to a surge of work in digital image processing
    • 1964: Computers used to improve the quality of images of the moon taken by the Ranger 7 probe
    • Such techniques were used b in other space missions including the Apollo landings (^) A picture of the moon taken by the Ranger 7 probe Images taken from Gonzalez & Woods, Digital Image Processing (2002) minutes before landing Docsity.com

History of DIP (cont…)

  • 1980s - Today: The use of digital image processing techniques has exploded and they are now used for all kinds of tasks in all kinds of areas
    • Image enhancement/restoration
    • Artistic effects
    • Medical visualisation
    • Industrial inspection
    • Law enforcement
    • Human computer interfaces

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Examples: Image Enhancement

  • One of the most common uses of DIP techniques: improve quality, remove noise etc

Images taken from Gonzalez & Woods, Digital Image Processing (2002) Docsity.com

Examples: Artistic Effects

  • Artistic effects are used to make images more visually appealing, to add special effects and to make composite images

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Examples: Medicine

  • Take slice from MRI scan of canine heart, and find boundaries between types of tissue
    • Image with gray levels representing tissue density
    • Use a suitable filter to highlight edges

Images taken from Gonzalez & Woods, Digital Image Processing (2002) Original MRI Image of a Dog Heart (^) Edge Detection Image Docsity.com

Examples: GIS (cont…)

  • Night-Time Lights of the World data set
    • Global inventory of human settlement
    • Not hard to imagine the kind of analysis that might be done using this data

Images taken from Gonzalez & Woods, Digital Image Processing (2002) Docsity.com

Examples: Industrial Inspection

  • Human operators are expensive, slow and unreliable
  • Make machines do the job instead
  • Industrial vision systems are used in all kinds of industries
  • Can we trust them?

Images taken from Gonzalez & Woods, Digital Image Processing (2002) Docsity.com

Examples: Law Enforcement

  • Image processing techniques are used extensively by law enforcers
    • Number plate recognition for speed cameras/automated toll systems
    • Fingerprint recognition
    • Enhancement of CCTV

Images taken from Gonzalez & Woods, Digital Image Processing (2002)images Docsity.com

Examples: HCI

  • Try to make human computer interfaces more natural
    • Face recognition
    • Gesture recognition
  • Does anyone remember the user interface from “Minority Report”?
  • These tasks can be extremely difficult

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