Digital image processing
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The document is an introduction to a course on digital image processing. It begins with definitions of digital images and digital image processing. It then provides a brief history of digital image processing, highlighting early applications in newspapers and space exploration. It also gives examples of current applications in areas like medicine, mapping, industrial inspection, and human-computer interfaces. Finally, it outlines some key stages in digital image processing pipelines like image acquisition, enhancement, restoration, segmentation, and compression.
Digital image processing
- 1. Digital Image Processing: Introduction Brian Mac Namee Brian.MacNamee@comp.dit.ie Course Website: http://www.comp.dit.ie/bmacnamee
- 2. 2 of 36 Introduction “One picture is worth more than ten thousand words” Anonymous
- 3. 3 of 36 Miscellanea Lectures: – Thursdays 12:00 – 13:00 – Fridays 15:00 – 16:00 Labs: – Wednesdays 09:00 – 11:00 Web Site: www.comp.dit.ie/bmacnamee/ – Previous year’s slides are available here – Slides etc will also be available on WebCT E-mail: Brian.MacNamee@dit.ie
- 4. 4 of 36 References “Digital Image Processing”, Rafael C. Gonzalez & Richard E. Woods, Addison-Wesley, 2002 – Much of the material that follows is taken from this book “Machine Vision: Automated Visual Inspection and Robot Vision”, David Vernon, Prentice Hall, 1991 – Available online at: homepages.inf.ed.ac.uk/rbf/BOOKS/VERNON/
- 5. 5 of 36 Contents This lecture will cover: – What is a digital image? – What is digital image processing? – History of digital image processing – State of the art examples of digital image processing – Key stages in digital image processing
- 6. Images taken from Gonzalez & Woods, Digital Image Processing (2002) 6 of 36 What is a Digital Image? A digital image is a representation of a twodimensional image as a finite set of digital values, called picture elements or pixels
- 7. Images taken from Gonzalez & Woods, Digital Image Processing (2002) 7 of 36 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
- 8. 8 of 36 What is a Digital Image? (cont…) Common image formats include: – 1 sample per point (B&W or Grayscale) – 3 samples per point (Red, Green, and Blue) – 4 samples per point (Red, Green, Blue, and “Alpha”, a.k.a. Opacity) For most of this course we will focus on grey-scale images
- 9. 9 of 36 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
- 10. 10 of 36 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 Mid Level Process High Level Process Input: Image Output: Image Input: Image Output: Attributes Input: Attributes Output: Understanding Examples: Noise removal, image sharpening Examples: Object recognition, segmentation Examples: Scene understanding, autonomous navigation In this course we will stop here
- 11. Images taken from Gonzalez & Woods, Digital Image Processing (2002) 11 of 36 History of Digital Image Processing Early 1920s: One of the first applications of digital imaging was in the newspaper industry – The Bartlane cable picture transmission service Early digital image – Images were transferred by submarine cable between London and New York – Pictures were coded for cable transfer and reconstructed at the receiving end on a telegraph printer
- 12. Images taken from Gonzalez & Woods, Digital Image Processing (2002) 12 of 36 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
- 13. Images taken from Gonzalez & Woods, Digital Image Processing (2002) 13 of 36 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 in other space missions including the Apollo landings A picture of the moon taken by the Ranger 7 probe minutes before landing
- 14. Images taken from Gonzalez & Woods, Digital Image Processing (2002) 14 of 36 History of DIP (cont…) 1970s: Digital image processing begins to be used in medical applications – 1979: Sir Godfrey N. Hounsfield & Prof. Allan M. Cormack share the Nobel Prize in medicine for the invention of tomography, the technology behind Computerised Axial Tomography (CAT) scans Typical head slice CAT image
- 15. 15 of 36 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
- 16. Images taken from Gonzalez & Woods, Digital Image Processing (2002) 16 of 36 Examples: Image Enhancement One of the most common uses of DIP techniques: improve quality, remove noise etc
- 17. 17 of 36 Examples: The Hubble Telescope Launched in 1990 the Hubble telescope can take images of very distant objects However, an incorrect mirror made many of Hubble’s images useless Image processing techniques were used to fix this
- 18. 18 of 36 Examples: Artistic Effects Artistic effects are used to make images more visually appealing, to add special effects and to make composite images
- 19. Images taken from Gonzalez & Woods, Digital Image Processing (2002) 19 of 36 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 Original MRI Image of a Dog Heart Edge Detection Image
- 20. Images taken from Gonzalez & Woods, Digital Image Processing (2002) 20 of 36 Examples: GIS Geographic Information Systems – Digital image processing techniques are used extensively to manipulate satellite imagery – Terrain classification – Meteorology
- 21. Images taken from Gonzalez & Woods, Digital Image Processing (2002) 21 of 36 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
- 22. Images taken from Gonzalez & Woods, Digital Image Processing (2002) 22 of 36 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?
- 23. 23 of 36 Examples: PCB Inspection Printed Circuit Board (PCB) inspection – Machine inspection is used to determine that all components are present and that all solder joints are acceptable – Both conventional imaging and x-ray imaging are used
- 24. Images taken from Gonzalez & Woods, Digital Image Processing (2002) 24 of 36 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
- 25. 25 of 36 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
- 26. 26 of 36 Key Stages in Digital Image Processing Image Restoration Morphological Processing Image Enhancement Segmentation Image Acquisition Object Recognition Problem Domain Representation & Description Colour Image Processing Image Compression
- 27. Images taken from Gonzalez & Woods, Digital Image Processing (2002) 27 of 36 Key Stages in Digital Image Processing: Image Aquisition Image Restoration Morphological Processing Image Enhancement Segmentation Image Acquisition Object Recognition Problem Domain Representation & Description Colour Image Processing Image Compression
- 28. Images taken from Gonzalez & Woods, Digital Image Processing (2002) 28 of 36 Key Stages in Digital Image Processing: Image Enhancement Image Restoration Morphological Processing Image Enhancement Segmentation Image Acquisition Object Recognition Problem Domain Representation & Description Colour Image Processing Image Compression
- 29. Images taken from Gonzalez & Woods, Digital Image Processing (2002) 29 of 36 Key Stages in Digital Image Processing: Image Restoration Image Restoration Morphological Processing Image Enhancement Segmentation Image Acquisition Object Recognition Problem Domain Representation & Description Colour Image Processing Image Compression
- 30. Images taken from Gonzalez & Woods, Digital Image Processing (2002) 30 of 36 Key Stages in Digital Image Processing: Morphological Processing Image Restoration Morphological Processing Image Enhancement Segmentation Image Acquisition Object Recognition Problem Domain Representation & Description Colour Image Processing Image Compression
- 31. Images taken from Gonzalez & Woods, Digital Image Processing (2002) 31 of 36 Key Stages in Digital Image Processing: Segmentation Image Restoration Morphological Processing Image Enhancement Segmentation Image Acquisition Object Recognition Problem Domain Representation & Description Colour Image Processing Image Compression
- 32. Images taken from Gonzalez & Woods, Digital Image Processing (2002) 32 of 36 Key Stages in Digital Image Processing: Object Recognition Image Restoration Morphological Processing Image Enhancement Segmentation Image Acquisition Object Recognition Problem Domain Representation & Description Colour Image Processing Image Compression
- 33. Images taken from Gonzalez & Woods, Digital Image Processing (2002) 33 of 36 Key Stages in Digital Image Processing: Representation & Description Image Restoration Morphological Processing Image Enhancement Segmentation Image Acquisition Object Recognition Problem Domain Representation & Description Colour Image Processing Image Compression
- 34. 34 of 36 Key Stages in Digital Image Processing: Image Compression Image Restoration Morphological Processing Image Enhancement Segmentation Image Acquisition Object Recognition Problem Domain Representation & Description Colour Image Processing Image Compression
- 35. 35 of 36 Key Stages in Digital Image Processing: Colour Image Processing Image Restoration Morphological Processing Image Enhancement Segmentation Image Acquisition Object Recognition Problem Domain Representation & Description Colour Image Processing Image Compression
- 36. 36 of 36 Summary We have looked at: – What is a digital image? – What is digital image processing? – History of digital image processing – State of the art examples of digital image processing – Key stages in digital image processing Next time we will start to see how it all works…