CS 414 - Spring 2014 CS 414 – Multimedia Systems Design Lecture 4 – Visual Perception and Digital Image Representation Klara Nahrstedt Spring 2014.

Slides:



Advertisements
Similar presentations
CS Spring 2009 CS 414 – Multimedia Systems Design Lecture 4 – Digital Image Representation Klara Nahrstedt Spring 2009.
Advertisements

Digital Image Fundamentals Selim Aksoy Department of Computer Engineering Bilkent University
Digital Image Fundamentals Selim Aksoy Department of Computer Engineering Bilkent University
Color & Light, Digitalization, Storage. Vision Rods work at low light levels and do not see color –That is, their response depends only on how many photons,
Digital Image Fundamentals Selim Aksoy Department of Computer Engineering Bilkent University
Motivation Application driven -- VoD, Information on Demand (WWW), education, telemedicine, videoconference, videophone Storage capacity Large capacity.
Color Image Processing
School of Computing Science Simon Fraser University
1 Perception. 2 “The consciousness or awareness of objects or other data through the medium of the senses.”
ECE 472/572 – Digital Image Processing Lecture 2 – Elements of Visual Perception and Image Formation 08/25/11.
CS Spring 2011 CS 414 – Multimedia Systems Design Lecture 4 – Visual Perception and Digital Image Representation Klara Nahrstedt Spring 2011.
Image Processing Lecture 2 - Gaurav Gupta - Shobhit Niranjan.
Klara Nahrstedt Spring 2009
CS Spring 2014 CS 414 – Multimedia Systems Design Lecture 5 – Digital Video Representation Klara Nahrstedt Spring 2014.
Lab #5-6 Follow-Up: More Python; Images Images ● A signal (e.g. sound, temperature infrared sensor reading) is a single (one- dimensional) quantity that.
TOPIC 4 INTRODUCTION TO MEDIA COMPUTATION: DIGITAL PICTURES Notes adapted from Introduction to Computing and Programming with Java: A Multimedia Approach.
Sensation & Perception
Images, Sound, and Multimedia. No Surprises Images, Sound, Music, and Movies – It’s all numbers – Binary Numbers Today we’ll discuss how multimedia is.
.  Sensation: process by which our sensory receptors and nervous system receive and represent stimulus energy  Perception: process of organizing and.
Intelligent Vision Systems Image Geometry and Acquisition ENT 496 Ms. HEMA C.R. Lecture 2.
Chapter 1. Introduction. Goals of Image Processing “One picture is worth more than a thousand words” 1.Improvement of pictorial information for human.
CIS 601 Image Fundamentals Longin Jan Latecki Slides by Dr. Rolf Lakaemper.
Image Representation. Digital Cameras Scanned Film & Photographs Digitized TV Signals Computer Graphics Radar & Sonar Medical Imaging Devices (X-Ray,
Digital Image Processing Part 1 Introduction. The eye.
CS Spring 2009 CS 414 – Multimedia Systems Design Lecture 3 – Digital Audio Representation Klara Nahrstedt Spring 2009.
DIGITAL IMAGE. Basic Image Concepts An image is a spatial representation of an object An image can be thought of as a function with resulting values of.
University of Kurdistan Digital Image Processing (DIP) Lecturer: Kaveh Mollazade, Ph.D. Department of Biosystems Engineering, Faculty of Agriculture,
CS Spring 2012 CS 414 – Multimedia Systems Design Lecture 4 – Visual Perception and Digital Image Representation Klara Nahrstedt Spring 2012.
Intelligent Vision Systems Image Geometry and Acquisition ENT 496 Ms. HEMA C.R. Lecture 2.
CS Spring 2014 CS 414 – Multimedia Systems Design Lecture 3 – Digital Audio Representation Klara Nahrstedt Spring 2014.
CS Spring 2010 CS 414 – Multimedia Systems Design Lecture 4 – Audio and Digital Image Representation Klara Nahrstedt Spring 2010.
CS Spring 2014 CS 414 – Multimedia Systems Design Lecture 19 – Multimedia Transport Subsystem (Part 2) + Midterm Review Klara Nahrstedt Spring 2014.
An Introduction to Digital Image Processing Dr.Amnach Khawne Department of Computer Engineering, KMITL.
Unit 4: Sensation & Perception
Digital Video Representation Subject : Audio And Video Systems Name : Makwana Gaurav Er no.: : Class : Electronics & Communication.
MODULE #13: VISION. Vision Transduction: transformation of stimulus energy (light, sound, smells, etc.) to neural impulses our brains can interpret. Our.
Image Perception ‘Let there be light! ‘. “Let there be light”
Lifecycle from Sound to Digital to Sound. Characteristics of Sound Amplitude Wavelength (w) Frequency ( ) Timbre Hearing: [20Hz – 20KHz] Speech: [200Hz.
Vision AP Psych Transduction – converting one form of energy into another In sensation, transforming stimulus energies such as sights, sounds,
The Visual Sense: Sight EQ: What is the process though which we see and how do we differentiate between different objects and types of motion?
Color Models Light property Color models.
CS 115: Computing for The Socio-Techno Web
Display Issues Ed Angel
Sampling, Quantization, Color Models & Indexed Color
Color Image Processing
Color Image Processing
25.2 The human eye The eye is the sensory organ used for vision.
Transduction Transformation of stimulus energies to electrochemical energy of neural impulses Sensory receptors are responsible for transduction Rods and.
Digital Image Processing (DIP)
Color Image Processing
Vision.
Digital 2D Image Basic Masaki Hayashi
Sensation and Perception
Chapter 5 Vision.
Introduction to Computer Graphics with WebGL
Prodi Teknik Informatika , Fakultas Imu Komputer
Chapter 6 Sensation and Perception
Digital Image Processing
CIS 601 Image Fundamentals
Engineering Math Physics (EMP)
Digital Image Fundamentals
Defining Sensation and Perception
VISION Module 18.
Color Image Processing
CIS 595 Image Fundamentals
Color Image Processing
Digital Image Processing
Visuals are analog signals...
Experiencing the World
(Do Now) Journal What is psychophysics? How does it connect sensation with perception? What is an absolute threshold? What are some implications of Signal.
Presentation transcript:

CS Spring 2014 CS 414 – Multimedia Systems Design Lecture 4 – Visual Perception and Digital Image Representation Klara Nahrstedt Spring 2014

CS Spring 2014 Administrative Groups are formed and names have been sent to Engineering IT and Barb Leisner We will inform you about group directories as soon as we have information from Engineering IT

Administrative Leasing Process from Barb Leisner  Lease one Logitech camera - two cameras within one group to start MP1, and then for MP2/MP3.  Leasing process starts on January 31  Pick up the camera from Barb Leisner office, 2312 SC  Bring your student ID to sign for the camera  Each cs414 group is responsible for his/her own camera if you loose it (or badly damage) and you don’t have police report, you pay for it (charged to your student account at the end of the semester)  Hours to pick up camera: Monday –Friday 9am-5pm  No camera pickup on Saturday and Sunday CS Spring 2014

Today Introduced Concepts Important Metric for Digital Audio  Signal-to-Noise Ratio (dB) Human Visual System Digital Images  Sampling  Quantization  Spatial Resolution CS Spring 2014

Signal-to-Noise Ratio (metric to quantify quality of digital audio) CS Spring 2014

Signal To Noise (SNR) Ratio Measures strength of signal to noise SNR (in DB)= Given sound form with amplitude in [-A, A] Signal energy = A 0 -A CS Spring 2014

Modeling of Noise - Quantization Error Difference between actual and sampled value  amplitude between [-A, A]  quantization levels = N e.g., if A = 1, N = 8, = 1/4 CS Spring 2014

Compute Signal to Noise Ratio Signal energy = ; Noise energy = ; Noise energy = Signal-to-Noise = SNR depends on number of bits (number of quantization levels) assigned to signal Every bit increases SNR by ~ 6 decibels

Integrating Aspects of Multimedia CS Spring 2014 Image/Video Capture Image/Video Information Representation Media Server Storage Transmission Compression Processing Audio/Video Presentation Playback Audio/Video Perception/ Playback Audio Information Representation Transmission Audio Capture A/V Playback

Human Visual System Eyes, optic nerve, parts of the brain Transforms electromagnetic energy

Human Visual System Image Formation  cornea, sclera, pupil, iris, lens, retina, fovea Transduction  retina, rods, and cones  Retina has photosensitive receptors at back of eye Processing  optic nerve, brain

Rods vs Cones (Responsible for us seeing brightness and color) Contain photo-pigment Respond to low energy Enhance sensitivity Concentrated in retina, but outside of fovea One type, sensitive to grayscale changes Contain photo-pigment Respond to high energy Enhance perception Concentrated in fovea, exist sparsely in retina Three types, sensitive to different wavelengths ConesRods CS Spring 2014

Tri-stimulus Theory 3 types of cones (6/7 Mil. of them)  Red = L cones, Green = M cones, Blue = S cones  Ratio differentiates for each person  E.g., Red (64%), Green (32%), rest S cones  E.g., L(50.6%), M(44.2%), rest S cones Each type most responsive to a narrow band electro-magnetic waves  red and green absorb most energy, blue the least Light stimulates each set of cones differently, and the ratios produce sensation of color CS Spring 2014

Color and Visual System Color refers to how we perceive a narrow band of electromagnetic energy  source, object, observer Visual system transforms light energy into sensory experience of sight

Color Perception (Color Theory) Hue  Refers to pure colors  dominant wavelength of the light Saturation  Perceived intensity of a specific color  how far color is from a gray of equal intensity Brightness (lightness)  perceived intensity CS Spring 2014 Hue Scale Saturation Original lightness Source: Wikipedia

Digitalization of Images – Capturing and Processing CS Spring 2014

Capturing Real-World Images Picture – two dimensional image captured from a real-world scene that represents a momentary event from the 3D spatial world CS Spring 2014 W3 W1 W2 r s Fr= function of (W1/W3); s=function of (W2/W3)

Image Concepts - Sampling An image is a function of intensity values over a 2D plane I(r,s) Sample function at discrete intervals to represent an image in digital form  matrix of intensity values for each color plane  intensity typically represented with 8 bits Sample points are called pixels CS Spring 2014

Digital Image Sampling Sample = pixel Image Size (in pixels) Image Size = Height x Width (in pixels) 320x240 pixels 640x480 pixels 1920x1080pixels CS Spring 2014

Digital Images - Quantization Quantization = number of bits per pixel Example: if we would sample and quantize standard TV picture (525 lines) by using VGA (Video Graphics Array),  video controller creates matrix 640x480pixels, and  each pixel is represented by 8 bit integer (256 discrete gray levels) CS Spring 2014

Image Representations Black and white image  single color plane with 2 bits Grey scale image  single color plane with 8 bits Color image  three color planes each with 8 bits  RGB, CMY, YIQ, etc. Indexed color image  single plane that indexes a color table Compressed images  TIFF, JPEG, BMP, etc. 2gray levels4 gray levels

Digital Image Representation (3 Bit Quantization) CS Spring 2014

Color Quantization Example of 24 bit RGB Image CS Spring bit Color Monitor

Image Representation Example bit RGB Representation (uncompressed) Color Planes

Graphical Representation CS Spring 2014

Image Properties (Color) CS Spring 2014

Color Histogram CS Spring 2014

Spatial and Frequency Domains Spatial domain  refers to planar region of intensity values at time t Frequency domain  think of each color plane as a sinusoidal function of changing intensity values  refers to organizing pixels according to their changing intensity (frequency) CS Spring 2014

Spatial Resolution and Brightness Spatial Resolution (depends on: )  Image size  Viewing distance Brightness  Perception of brightness is higher than perception of color  Different perception of primary colors Relative brightness: green:red:blue= 59%:30%:11% CS Spring 2014 Source: wikipedia

Image Size (in Bits) Image Size = Height x Width X Bits/pixel Example:  Consider image 320x240 pixels with 8 bits per pixel  Image takes storage 7680 x 8 bits = bits or 7680 bytes CS Spring 2014

Summary Important Image Processing Functions (see Computer Vision/Image Processing classes)  Filtering  Edge detection  Image segmentation  Image recognition Formatting Conditioning Marking Grouping Extraction Matching  Image synthesis CS Spring 2014