Digital Image Analysis and Processing CPE 0907544 Introduction - PowerPoint PPT Presentation

Digital Image Analysis and Processing CPE 0907544 Introduction Chapter 1 Dr. Iyad Jafar

Outline  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 2

What is a Digital Image?  An image can be defined as a two-dimensional function f(x,y) with x and y being the spatial coordinates and f is the amplitude  A digital image is the representation of an image using finite and discrete values for x, y and f  These values are called picture elements or pixels y 3 x

What is a Digital Image?  Pixels’ values typically represent gray levels, colors, heights, opacities etc  Remember that digitization implies that a digital image is an approximation of a real scene 1 pixel 4 Actual Digitized

What is a Digital Image?  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 5

What is Digital Image Processing?  Generally, DIP refers to the processing of digital images by a computer  Two principle application areas for DIP  Improving the pictorial information for better interpretation for human or machine  Processing of image data for storage , transmission and representation for autonomous machine perception 6

What is DIP?  There is no consensus on the boundaries of DIP  Considering DIP as the field where the input and output are images is not true  However, consider three types of computerized processing Low Level Mid Level high Level Processing Processing Processing Input: image Input: image Input: image Output: image Output: attributes of Output: Understanding Example: Enhancement, image Example: Scene noise removal, Example: Segmentation, understanding, sharpening recognition autonomous navigation autonomous navigation In this course we will 7 stop somewhere here

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  Images were transferred by submarine Early digital image cable between London and NewYork  Pictures were coded for cable transfer and reconstructed at the receiving end on a telegraph printer 8

History of Digital Image Processing  Mid to late 1920s: Improvements to the Bartlane system resulted in higher quality images  New processes based on photographic techniques Early 15 tone digital image  Increased number of tones in reproduced images  These were digital images, yet no computers were involved ?! Improved 9 digital image

History of Digital Image Processing  Early 1960s  Appearance of digital computers capable of performing DIP tasks and the development of space program motivated the birth of DIP  For example, computers were used to improve the quality of images of the moon taken by the Ranger 7 10 probe in 1964

History of Digital Image Processing  Late 1960s - 1970s  Digital image processing pierced into medical, remote earth sensing, and astronomy  1979: the invention of Computerized Axial T omography (CAT) by Sir Godfrey N. Hounsfield & Prof. Allan M. CAT Head image Satellite image 11

History of Digital Image Processing  1980s –T oday  DIP is no longer restricted to medicine and space applications  Some new applications  Image enhancement/restoration  Artistic effects  Medical visualisation  Industrial inspection  Law enforcement  Human computer interfaces 12

Examples of Fields that Use DIP  The fields that use DIP are diverse  One way to explore such fields is to categorize images based on their source  Electromagnetic energy: visible and invisible  Acoustic energy  Ultrasonic  Electronic  Synthetic images 13

Examples of Fields that Use DIP  The electromagnetic spectrum 14

Examples of Fields that Use DIP  Gamma-Ray imaging  Nuclear medicine (Positron Emission Tomography – PET)  Patient is injected with a radioactive material that emits gamma rays as it decays  The rays are collected by gamma cameras and the image is reconstructed  Astronomical Observations  Gamma rays radiated by outer space objects Gamma rays of a star 15

Examples of Fields that Use DIP  X-ray Imaging  Medical diagnosis and industrial inspection  X-rays are generated when an accelerated electrons hits the nucleus of an atom in x-ray tube  The intensity of x-ray drops as it propagates through materials and is collected on a film at the other end  CAT is the most popular x-ray imaging system as it is capable of producing 3D images 16

Examples of Fields that Use DIP  Ultraviolet Imaging  Fluorescence microscopy  When the invisible UV hits a fluorescent material, electrons are excited and elevate to higher levels  Eventually these electrons move back to a lower level and emits light in the visible spectrum  Useful in studying/detecting materials capable of fluorescing  Astronomical observation 17 Endothelial Cell The Sun imaged in the ultraviolet band

Examples of Fields that Use DIP  Imaging in the visible band  The most common and familiar and is often used with visual imaging  Numerous operations can be performed on the acquired images (enhancement, inspection, law-enforcement)  Images are acquired with sensors that are sensitive to the visible light Automated Bubbles in clear license plate plastic Cholesterol Microprocessor reading 18

Examples of Fields that Use DIP  Imaging in the infrared band  Infrared radiation is emitted by all objects based on their temperatures  The amount of radiation emitted by an object increases with temperature, therefore thermography allows one to see variations in temperature  For example  firefighters use it to see through smoke, find persons, and localize the base of a fire  power lines maintenance technicians locate overheating joints and parts 19

Examples of Fields that Use DIP  Imaging in the radio band  Mainly in medicine and aerospace  Magnetic Resonance Imaging (MRI)  the patient is placed in a powerful magnet and then exposed to radio waves that pass through his body  as a response, radio waves are emitted from the tissues with different strength based on tissue type and location MRI image for a knee Radio image for the Crab 20 Pulsar (young neutron star)

Examples of Fields that Use DIP  Acoustic Imaging  Geological exploration, medicine, and industry  Expose the object/area to sound waves and record the strength of the returning waves which is used to infer the underlying structure using a computer  Ultrasound imaging is perhaps the most popular Ultrasound image for a 21 baby

Examples of Fields that Use DIP  Computer generated images  Artistic images, computer graphics, animation 22

Key Stages in Digital Image Processing Image Segmentation Restoration Image Morphological Enhancement Processing Image Representation Acquisition & Description Object Problem Domain Recognition Colour Image Image Processing Compression 23

Key Stages in Digital Image Processing Image Acquisition Image Segmentation Restoration Image Morphological Enhancement Processing Image Representation Acquisition & Description Object Problem Domain Recognition Colour Image Image Processing Compression 24

Key Stages in Digital Image Processing Image Enhancement Image Segmentation Restoration Image Morphological Enhancement Processing Image Representation Acquisition & Description Object Problem Domain Recognition Colour Image Image Processing Compression 25

Key Stages in Digital Image Processing Image Restoration Image Segmentation Restoration Image Morphological Enhancement Processing Image Representation Acquisition & Description Object Problem Domain Recognition Colour Image Image Processing Compression 26

Key Stages in Digital Image Processing Segmentation Image Segmentation Restoration Image Morphological Enhancement Processing Image Representation Acquisition & Description Object Problem Domain Recognition Colour Image Image Processing Compression 27

Key Stages in Digital Image Processing Morphological Processing Image Segmentation Restoration Image Morphological Enhancement Processing Image Representation Acquisition & Description Object Problem Domain Recognition Colour Image Image Processing Compression 28

Key Stages in Digital Image Processing Object Recognition Image Segmentation Restoration Image Morphological Enhancement Processing Image Representation Acquisition & Description Object Problem Domain Recognition Colour Image Image Processing Compression 29

Key Stages in Digital Image Processing Representation & Description Image Morphological Restoration Processing Image Segmentation Enhancement Image Representation Acquisition & Description Object Problem Domain Recognition Colour Image Image Processing Compression 30