Digital Image Processing. T. Peynot. Chapter 1. Outline. Introduction

Transcription

1 Outline Part I: 1. to Digital Image Processing 2. Digital Image Fundamentals 3. Intensity Transformations and Spatial Filtering 4. Filtering in the Frequency Domain 5. Image Restoration and Reconstruction 6. Colour Image Processing

2 1. to Digital Image Processing 1. What is Digital Image Processing (DIP)? 2. The Origins of Digital Image Processing 3. Examples of Fields that Use Digital Image Processing 4. Fundamental Steps in Digital Image Processing 5. Components of an Image Processing System

3 1.1 What is Digital Image Processing (DIP)? Image Processing Image Analysis (or Image Understanding) Computer Vision (goal: emulate human vision, branch of Artificial Intelligence...) 3 types of computerized processes: 1. Low-level processes: reduction of noise, enhancement, sharpening 2. Mid-level processes: segmentation, description of objects, classification (recognition) 3. High-level processes: "making sense" of recognized objects => perform cognitive functions

4 1.1 What is Digital Image Processing (DIP)? Image = two-dimensional function f(x,y) where: x and y are spatial (plane) coordinates the amplitude of f at any (x,y) is called the intensity or gray level of the image at that point. x, y and intensity values all finite, discrete quantities => digital image DIP: processing digital images by means of a computer Elements of the image: picture elements, image elements, pels, pixels NB: Unlike humans, (digital) imaging machines can cover almost the entire Electromagnetic (EM) spectrum

5 1.2 The Origins of Digital Image Processing 1920s: Pictures sent by submarine cable between London and New York 1 week less than 3 hours 5 levels of gray (1922)

6 1.2 The Origins of Digital Image Processing 15 levels of gray (1929)

7 1.2 The Origins of Digital Image Processing Markers used for geometric corrections (distorsions)

8 1.3 Examples of Fields that Use Digital Image Processing EM waves: propagating sinusoidal waves of varying wavelengths Or: a stream of massless particles, each traveling in a wavelike pattern at the speed of light. Each particle contains a certain amount (or bundle) of energy. Each bundle of energy is called a photon

9 1.3 Examples of Fields that Use Digital Image Processing Gamma-Ray Imaging X-Ray Imaging Imaging in the Ultra-Violet Band Imaging in the Visible and Infrared Bands Imaging in the Microwave Band Imaging in the Radio Band Examples of Other Imaging Modalities

10 1.3.1 Gamma-Ray Imaging Bone scan PET: Positron Emission Tomography Major use: nuclear medicine and astronomical observations Cygnus Loop

11 1.3.2 X-Ray Imaging Chest X-ray Applications: Medical diagnostics, industry, astronomy Circuit boards Angiography CAT: Computerized Axial Tomography

12 1.3.3 Imaging in the Ultra-Violet Band Corn Applications: lithography, industrial inspection, microscopy, lasers, biological imaging, astronomical observations Fluorescence microscopy: collision of a UV radiation photon with an electron of fluorescent material => Emission of energy in the visible light region

13 1.3.4 Imaging in the Visible and Infrared Bands Applications (examples): light microscopy, astronomy, remote sensing, industry, law enforcement and robotics

14 Remote sensing Multispectral imaging

15 Weather observation NOAA: National Oceanographic and Atmospheric Administration Image obtained using sensors in the visible and infrared bands

16 Infrared Imaging

17 Inspection of manufactured goods

18 Law enforcement, automated counting, CSI

19 1.3.5 Imaging in the Microwave Band Dominant application: Radar Some radar waves can penetrate clouds, see through vegetation, ice, dry sand Up to 5800m above sea level. Valley floors lie about 4300m

20 1.3.6 Imaging in the Radio Band Major applications: medicine and astronomy MRI: Magnetic resonance Imaging Image of the responding pulse of radio waves emitted by the patient s tissues

21 1.3.7 Examples of Other Imaging Modalities Acoustic imaging, electron microscopy, synthetic (computer-generated) imaging Imaging using sound : applications in geological exploration, industry and medicine

22 Ultrasound imaging: e.g. in medicine (obstetrics): imaging of unborn babies High-frequency sound pulses into the body (1 to 5 MHz) travel into the body, hit boundary between tissues Reflected waves probe Display: distances and intensities of the echoes 2-D Image

23 Electron microscopy: use of focused beam of electrons instead of light to image a specimen

24 Images generated by computer E.g.: Fractal: iterative reproduction of a basic pattern according to some mathematical rules Applications of computer generated images: medical training, criminal forensics, special effects Fractal grown radially out of a centre point

25 Images generated by computer Applications of computer generated images: medical training, criminal forensics, special effects CGI: Computer-Generated Imagery 2004 Dreamworks SKG 1991 Universal Studios

26 Examples of robotics applications Face detection and tracking Path following [ , LAAS-CNRS ]

27 Examples of robotics applications Digital Elevation Map [ , LAAS-CNRS ]

28 Examples of robotics applications [ , ACFR, University of Sydney ]

29 1.4 Fundamental Steps in Digital Image Processing (in the book)

30 1.5 Components of an Image Processing System Short-term storage (during processing). e.g.: RAM, frame buffers On-line storage (fast recall). E.g. disks Archival storage (infrequent access). E.g. magnetic tapes, optical disks e.g. printers, film cameras, digital units

31 Glossary (D)IP = (Digital) Image Processing CV = Computer Vision EM = ElectroMagnetic