ch-1.1 image processing fundamentals.pptx

fundamentals of DIP

1. Digital Image Processing Fundamentals 1

2. What is Image ? A n im a ge i s a spatial repr e sentation o f a tw o - dimensional or three-dimensional scene. A n image i s a n arr a y , o r a mat rix pixels (picture elements) arranged in columns and rows. 2

3. What is Image Processing 3

4. What is Image Processing 4

5. What is Image Processing 5

6. What is Image Processing One picture is worth more than thousands of words. 6

7.  Int erest i n digit a l im a ge proces s ing met ho d s stems from two principal application areas: I m provement o f pic t orial i n for m ation for human interpretation Processing of image data for storage, transmission, and representation for autonomous machine perception WHY…..digital image processing…??? 7

8. DIP Definition: A D i s c ip l ine i n Which B o th t h e Input an d O u tput o f a Process are Images. W HAT I S D IGITAL I MAGE P ROCESSING ? Process I m age I m age 8

9. An image may be defined as a two-dimensional function, f(x, y) , where x a n d y are s p at i al (p l an e ) c o ordinates, and the ampl i tude o f f at a ny pa i r of c o o rd i nates ( x, y ) is c a l l ed the intensity or gray level of the image at that point. Digital Image: When x , y and the in t en s ity valu e s of f a re a ll fi n it e , discrete quantities, we call the image a digital image. What Is Digital Image ? The field of digital image processing refers to processing digital images by means of a digital computer. Color Image: 9  

10. Quantization An Image: g (x , y) D i scret iz a tion g ( i , j ) f ( i , j ) Digital Image f ( i , j ) : Picture Element, Image Element, Pel, Pixel What Is Digital Image ? 10 10

11. Image Processing V is i on Lo w - L e vel Process Mi d - L e vel Process H i g h - L e vel Process Reduce Noise Contrast Enhancement Image Sharpening Segmenta t ion Classification Making Sense of an Ensemble of Recognized Objects Image Analysis W HAT I S D IGITAL I MAGE P ROCESSING ? 11 11

12. One of the first applications of digital images was in the newspaper industry, when pictures were first sent by submarine cable between London and New York. Introduction of the Bartlane cable picture transmission system in the early 1920s reduced the time required to transport a picture across the Atlantic from more than a week to less than three hours. Origins of Digital Image Processing A di g ital pic t ure pr o d u ced in 1921 from a coded tape by a teleg r a p h p r i nt e r w ith spe c ial type faces. 12 12

13. Today, there is almost no area of technical endeavor that is not impacted in some way by digital image processing. Gamma-Ray Imaging X-Ray Imaging Imaging in the Ultraviolet Band Imaging in the Visible and Infrared Bands Imaging in the Microwave Band Imaging in the Radio Band Fields that Use Digital Image Processing 13 13

14. Gamma-Ray Imaging Major uses of imaging based on gamma rays include nuclear medicine. In nuclear medicine, the approach is to inject a patient with a radioactive isotope that emits gamma rays as it decays. Images are produced from the emissions collected by gamma ray detectors. Bone scan PET Cygnus loop Reactor valve 14 14

15. X-Ray Imaging Cygnus loop PCB Chest X - R a y Head CT A n g i o g ram 15 15

16. Applications and Research Topics 16

17.  Document Handling Applications and Research Topics 17

18.  Signature Verification Applications and Research Topics 18

19.  Biometrics Applications and Research Topics 19

20.  Fingerprint Verification / Identification Applications and Research Topics 20

21.  Object Recognition Applications and Research Topics 21

22.  Target Recognition Department of Defense (Army, Air force, Navy) Applications and Research Topics 22

23.  Interpretation of Aerial Photography Interpretation of aerial photography is a problem domain in both computer vision and registration . Applications and Research Topics 23

24.  Autonomous Vehicles Land, Underwater, Space Applications and Research Topics 24

25.  Traffic Monitoring Applications and Research Topics 25

26.  Traffic Monitoring Applications and Research Topics 26

27.  Face Detection Applications and Research Topics 27

28.  Face Recognition Applications and Research Topics 28

29.  Face Detection/Recognition Research Applications and Research Topics 29

30.  Facial Expression Recognition Applications and Research Topics 30

31.  Hand Gesture Recognition Smart Human-Computer User Interfaces Sign Language Recognition Applications and Research Topics 31

32.  Human Activity Recognition Applications and Research Topics 32

33.  Medical Applications Applications and Research Topics breast cancer skin cancer 33

34.  Morphing Applications and Research Topics 34

35.  Inserting Artificial Objects into a Scene Applications and Research Topics 35

36. Fundamental Steps in Digital Image Processing 36

37. Fundamental Steps in Digital Image Processing 37

38. Fundamental Steps in Digital Image Processing Essential steps when processing digital images: Acquisition Enhancement Restoration Color image restoration Wavelets Morphological processing Segmentation R e presentation Recognition Outputs are digital images Outputs are attributes of the image 38 38

39. Fundamental Steps in Digital Image Processing  Image acquisition is the first process. Ge n eral l y , the ima g e a c q u isit i on sta g e in v o l ves preprocessing, such as scaling. 39

40. Fundamental Steps in Digital Image Processing  Image enhancement is the process of manipulating an image so that the result is more suitable than the original for a specific application. There is no general “theory” of image enhancement. When an image is processed for visual interpretation, the viewer is the ultimate judge of how well a particular method works. 40

41.  Image Restoration is an area that also deals with improving the appearance of an image. However, unlike enhancement, which is subjective, image restoration is objective, in the sense that restoration techniques tend to be based on mathematical or probabilistic models of image degradation . Fundamental Steps in Digital Image Processing 41

42.  Color Image Processing is an area that has been gaining in importance because of the significant increase in the use of digital images over the Internet.  Wavelets are the foundation for representing images in various degrees of resolution. Fundamental Steps in Digital Image Processing 42

43.  Compression , as the name implies, deals with techniques for reducing the storage required to save an image, or the bandwidth required to transmit it. This is true particularly in uses of the Internet. Fundamental Steps in Digital Image Processing 43

44. 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. A segmentation procedure brings the process a long way toward successful solution of imaging problems that require objects to be identified individually. In general, the more accurate the segmentation, the more likely recognition is to succeed. Fundamental Steps in Digital Image Processing 44

45. Representation and description almost always follow the output of a segmentation stage, which usually is raw pixel data. Boundary representation is appropriate when the focus is on external shape characteristics, such as corners and inflections. Regional representation is appropriate when the focus is on internal properties, such as texture or skeletal shape. Description, also called feature selection, deals with extracting attributes that result in some quantitative information of interest or are basic for differentiating one class of objects from another. Recognition is the process that assigns a label (e.g., “vehicle”) to an object based on its descriptors. Digital image processing with the development of methods for recognition of individual objects. Fundamental Steps in Digital Image Processing 45

46. General Purpose Image Processing System 46

47. Specialized image processing hardware usually consists of the digitizer, plus hardware that performs other primitive operations, such as an arithmetic logic unit (ALU), that performs arithmetic and logical operations in parallel on entire images. This type of hardware sometimes is called a front-end subsystem, and its most distinguishing characteristic is speed. General Purpose Image Processing System 47

48. The Computer in an image processing system is a general-purpose computer and can range from a PC to a supercomputer. In dedicated applications, sometimes custom computers are used to achieve a required level of performance, but our interest here is on general- purpose image processing systems. In these systems, almost any well-equipped PC-type machine is suitable for off-line image processing tasks. General Purpose Image Processing System 48

49.  Software for image processing consists of specialized modules that perform specific tasks.  More sophi s ti c ated p a c k ages allow the integration of tho s e software mo d ules from at and genera l - p u r p ose lea s t o ne c o m p uter s o f t w a re com m a n d s language. General Purpose Image Processing System 49

50. General Purpose Image Processing System Mass storage capability is a must in image processing applications. An image of size 1024 * 1024 pixels, in which the intensity of each pixel is an 8-bit quantity, requires one megabyte of storage space if the image is not compressed. Digital storage for image processing applications falls into three principal categories: Short-term storage for use during processing, On-line storage for relatively fast recall, and Archival storage , characterized by infrequent access. Storage is measured in: bytes, Kbytes, Mbytes, 50  Gbytes, and 50

51. Image displays in use today are mainly color (preferably flat screen) TV monitors. Monitors are driven by the outputs of image and graphics display cards that are an integral part of the computer system. In some cases, it is necessary to have stereo displays, and these are implemented in the form of headgear containing two small displays embedded in goggles worn by the user. General Purpose Image Processing System 51

52. Hardcopy devices for recording images include laser printers, film cameras, heat-sensitive devices, inkjet units, and digital units, such as optical and CDROM disks. Networking is almost a default function in any computer system in use today. In dedicated networks, this typically is not a problem, but communications with remote sites via the Internet are not always as efficient. General Purpose Image Processing System 52

53. Image Processing Basics 53

54. Image Representation x y Origin (0,0) Pi x el 54

55. A digital image is composed of M rows and N columns of pixels each storing a value Pixel values are most often grey levels in the range 0-255(black- white) We will see later on that images can easily be represented as matrices. Image Representation 55

56. Image Representation 56

57.  Images are typically generated by illuminating a scene and absorbing the the objects in e n ergy reflected by that scene Image Acquisition 57

58. Incoming energy lands on a sensor material responsive to that type of energy and this generates a voltage Collections of sensors are arranged to capture images Image Sensing Imaging Sensor Line of Image Sensors Array of Image Sensors 58 58

59. A digital sensor can only measure a limited number of samples at a discrete set of energy levels Quantisation is the process of converting a continuous analogue signal into a digital representation of this signal Image Sampling And Quantization 59

60.  Remember that a digital image is always only an approximation of a real world scene. Image Sampling And Quantization 60

61. Th e s p at i al res o lut i on of an i ma g e i s d etermin e d by how sampling was carried out Sp a tial res o lution sim p l y refers t o the smallest discernable detail in an image Vision specialists will often talk about pixel size Graphic designers will talk about dots per inch (DPI) Spatial Resolution 61

62. Spatial Resolution Vision specialists will often talk about pixel size 62 62

63. Spatial Resolution 1024 * 1024 512 * 512 256 * 256 128 * 128 64 * 64 32 * 32 Graphic designers will talk about dots per inch 63 63

64. Inten s ity l e v el r e s o l ution refers t o the n u mb e r of intensity levels used to represent the image Th e mor e i n ten s ity levels use d, the finer the l e v e l of detail discernable in an image Intensity level resolution is usually given in terms of the number of bits used to store each intensity level Intensity Level Resolution Number of Bits Number of Intensity Levels Examples 1 2 0, 1 2 4 00, 01, 10, 11 4 16 0000, 0101, 1111 8 256 00110011, 16 65,536 1010 1 1 1 1 1 1 1 1 0101 64 64

65. Intensity Level Resolution 64 grey levels (6 bpp) 32 grey levels (5 bpp) 16 grey levels (4 bpp) 8 grey levels (3 bpp) 4 grey levels (2 bpp) 2 grey levels (1 bpp) 256 grey levels (8 bits per pixe1l)28 grey levels (7 bpp) 65 65

66. The big question with resolution is always how much is enough ? This all depends on what is in the image and what you would like to do with it Key questions include Does the image look aesthetically pleasing? Can you see what you need to see within the image? Resolution: How Much Is Enough?  The picture on the right is fine for counting the number of cars, but not for reading the number plate 66 66

67. Thank You… 67