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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) 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
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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
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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
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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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