“Digital Image Processing”, Second Edition 2002 -Rafael C. Gonzalez -Richard E. Woods

1. “Digital Image Processing”, Second Edition 2002 -Rafael C. Gonzalez -Richard E. Woods Center for Artificial Intelligence and RObotics (CAIRO)

2. “One picture is worth more than ten thousand words” Anonymous Center for Artificial Intelligence and RObotics (CAIRO)

3. Chapter 1. Introduction Center for Artificial Intelligence and RObotics (CAIRO)

4. Chapter Objectives: • Define the scope of the field that we call image processing. • Give a historical perspective of the origins of this field. • Examining some of the principal areas in which it is applied. • Discuss briefly the principal approaches used in digital image processing. • Give an overview of the components contained in a typical, general-purpose image processing system. Center for Artificial Intelligence and RObotics (CAIRO)

5. What is a Digital Image Processing ? • An image may be defined as a two-dimensional function, f(x, y), where x and y are spatial (plane) coordinates, and the amplitude of "f" at any pair of coordinates (x, y) is called the intensity or gray level of the image at that point. Center for Artificial Intelligence and RObotics (CAIRO)

6. What is a digital image Processing (cont…)? • When x, y, and the amplitude values of f are all finite, discrete quantities, we call the image a digital image. • Digital Image the representation of 2-D image as finite number of elements which called Pixels Center for Artificial Intelligence and RObotics (CAIRO)

7. What is a digital image Processing (cont…)? • DIP processing refers to processing digital images by means of a digital computer. • DIPis the use of computer algorithms to perform image processing on digital image. Center for Artificial Intelligence and RObotics (CAIRO)

8. Why Digital Image Processing ? • Vision is the most advanced of our senses, so it is not surprising that images play the single most important role in human perception. • Interest in digital image processing methods stems from two principal application areas : • 1- Improvement of pictorial information for human interpretation. • 2- Processing of image data for storage, transmission, and representation for autonomous machine perception. Center for Artificial Intelligence and RObotics (CAIRO)

9. High Level Process Mid Level Process Low Level Process Input: Attributes Output: Understanding Examples: Scene understanding, autonomous navigation Input: Image Output: Attributes Examples: Object recognition, segmentation Input: ImageOutput: Image Examples: Noise removal, image sharpening • Digital Image Processing (cont…)? • The continuum from image processing to computer vision can be broken up into low-, mid- and high-level processes Center for Artificial Intelligence and RObotics (CAIRO)

10. Early digital image • Historyof digital image processing Early 1920s: One of the first applications of digital imaging was in the newspaper industry. • - Images were transferred by submarine cable between London and New York. • - The Bartlane cable picture transmission service • - Pictures were coded for cable transfer and reconstructed at the receiving end on a telegraph printer Center for Artificial Intelligence and RObotics (CAIRO)

11. Improved digital image Early 15 tone digital image • Historyof digital image processing (cont…) Mid to late 1920s: Improvements to the Bartlane system resulted in higher quality images Center for Artificial Intelligence and RObotics (CAIRO)

12. Historyof digital image processing (cont…) • Late 1940s: Born of Digital Computer • DIP has been dependent on the development of digital computers and other supporting technologies (e.g., data storage, display and transmission) • 1950s ~ 1980s: series of key advances that led to computers powerful enough to be used for digital image processing • The invitation of the transistor. • The development of high level programming languages and development of operating system • Introduction by IBM of personal computer Center for Artificial Intelligence and RObotics (CAIRO)

13. Historyof digital image processing (cont…) • 1980s ~ Nowadays • Artistic effects • Medical Visualisation • Industrial Inspection • Law Enforcement Center for Artificial Intelligence and RObotics (CAIRO)

14. Examples of fields that use digital image processing • Sources of digital images • Electromagnetic(EM) energy • Acoustic imaging • Synthetic Center for Artificial Intelligence and RObotics (CAIRO)

15. 1- Gamma Rays • Applications: • Nuclear medicine • [radionuclide's] • [PET] • -astronomical observations Center for Artificial Intelligence and RObotics (CAIRO)

16. 2- X-Rays Applications: Medical and Industrial X-ray Tube Center for Artificial Intelligence and RObotics (CAIRO)

17. 3- Ultraviolet band - fluorescent Microscope Center for Artificial Intelligence and RObotics (CAIRO)

18. 4- Visible and Infrared band -photography -astronomy Center for Artificial Intelligence and RObotics (CAIRO)

19. 5- Microwave band Application : -Radar 6- Radio band Application : -MRI ( magnetic resonance imaging) Center for Artificial Intelligence and RObotics (CAIRO)

20. Other Non-Electro-Magnetic Imaging Modalities 1- Ultrasound images 2- Synthetic Center for Artificial Intelligence and RObotics (CAIRO)

21. Fundamental Steps in Digital Image Processing Center for Artificial Intelligence and RObotics (CAIRO)

22. Fundamental Steps in Digital Image Processing(Cont..) Image Acquisition Acquisition could be as simple as being given an image that is already in digital form. Center for Artificial Intelligence and RObotics (CAIRO)

23. Fundamental Steps in Digital Image Processing(Cont..) Image Enhancement the idea behind enhancement techniques is to bring out detail that is obscured, or simply to highlight certain features of interest in an image. Center for Artificial Intelligence and RObotics (CAIRO)

24. Fundamental Steps in Digital Image Processing(Cont..) Image Restoration An area that also deals with improving the appearance of an image. Center for Artificial Intelligence and RObotics (CAIRO)

25. Fundamental Steps in Digital Image Processing(Cont..) Color image processing Wavelets and multiresolution processing Center for Artificial Intelligence and RObotics (CAIRO)

26. Fundamental Steps in Digital Image Processing(Cont..) Compression reducing the storage required to save an image, or the bandwidth required to transmit it, Ex JPG,JPEG. Morphological Processing Center for Artificial Intelligence and RObotics (CAIRO)

27. Fundamental Steps in Digital Image Processing(Cont..) Segmentation Representation & Description Object Recognition The process that assigns a label (e.g., “vehicle”) to an object based on its descriptors. Center for Artificial Intelligence and RObotics (CAIRO)

28. Component Of an DIP System Center for Artificial Intelligence and RObotics (CAIRO)

29. Component Of an DIP System Center for Artificial Intelligence and RObotics (CAIRO)

30. Chapter 2. Image Processing Fundamentals Center for Artificial Intelligence and RObotics (CAIRO)

31. This chapter will cover: • The human visual system • Light and the electromagnetic spectrum • Image sensing and acquisition • Sampling, quantisation and resolution • Introduction to mathematical tools used in DIP Center for Artificial Intelligence and RObotics (CAIRO)

32. The human visual system Center for Artificial Intelligence and RObotics (CAIRO)

33. The human visual system (cont…) • 3 membranes enclose the eye • Cornea & sclera • Choroid • Retina Center for Artificial Intelligence and RObotics (CAIRO)

34. The human visual system (cont…) • The corena: is a tough, transparent tissue that covers the anterior surface of the eye. • The sclera: is an opaque membrance that encloses the remainder of the optic globe. Center for Artificial Intelligence and RObotics (CAIRO)

35. The human visual system (cont…) • The choroid : lies below scelra, it contains a network of blood vessels that serve as the major source of nutrition to the eye. • It is divided into the • 1-Ciliary body • 2- Iris diaphragm, which controls the amount of light that enters the pupil (2 mm ~ 8 mm). Center for Artificial Intelligence and RObotics (CAIRO)

36. The human visual system (cont…) • The retina lines the entire posterior portion. • Discrete light receptors are distributed over the surface of the retina: • cones (6-7 million per eye) and • rods (75-150 million per eye) Center for Artificial Intelligence and RObotics (CAIRO)

37. The human visual system (cont…) Center for Artificial Intelligence and RObotics (CAIRO)

38. The human visual system (cont…) Center for Artificial Intelligence and RObotics (CAIRO)

39. The human visual system (cont…) Image Formation in the Eye • focal length: Distance between the center of the lens and the retina • varies from 14 mm to 17 mm. • - Controlled by the tension in the fibers of the ciliary body: • To focus on distant objects – flattened lens • To focus on objects near eye – thicker lens Center for Artificial Intelligence and RObotics (CAIRO)

40. Light Receptor Brain • The human visual system (cont…) • Perception takes place by the relative excitation of light receptors. • These receptors transform radiant energy into electrical impulses that are decoded by the brain. Radiant Energy Center for Artificial Intelligence and RObotics (CAIRO)

41. The human visual system (cont…) • Example: • Calculation of retinal image of an object Center for Artificial Intelligence and RObotics (CAIRO)

42. The human visual system (cont…) Two Visual Systems of the Human Eye 1- Brightness Adaptation 2- Brightness Discrimination • Adaptation: is the ability of the eye to adapt of changes in the light intensity. • The human visual system can perceive approximately 1010 different light intensity levels • brightness adaptation level :iscurrent sensitivity level of the visual system. Center for Artificial Intelligence and RObotics (CAIRO)

43. The human visual system (cont…) • Subjective brightness (i.e. intensity as perceived by the HVS) is a logarithmic function of the light intensity incident on the eye. Center for Artificial Intelligence and RObotics (CAIRO)

44. The human visual system (cont…) • Weber ratio (the experiment) : • I: the background illumination • : the increment of illumination • Small Weber ratio indicates good discrimination • Larger Weber ratio indicates poor discrimination Center for Artificial Intelligence and RObotics (CAIRO)

45. The human visual system (cont…) Center for Artificial Intelligence and RObotics (CAIRO)

46. The human visual system (cont…) • The perceived brightness is not a simple function of intensity • Mach band pattern • Simultaneous contrast Center for Artificial Intelligence and RObotics (CAIRO)

47. The human visual system (cont…) • Mach band pattern Actual intensity Perceived intensity Center for Artificial Intelligence and RObotics (CAIRO)

48. The human visual system (cont…) • Simultaneous contrast Center for Artificial Intelligence and RObotics (CAIRO)

49. The human visual system (cont…) • Optical illusion Center for Artificial Intelligence and RObotics (CAIRO)

50. The light and the EM spectrum • Light is just a particular part of the electromagnetic spectrum that can be sensed by the human eye • The electromagnetic spectrum is split up according to the wavelengths of different forms of energy Center for Artificial Intelligence and RObotics (CAIRO)