Introduction to Video Analysis

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  • Topic: Parallel port, Universal Serial Bus, Digital camera
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Introduction to Video analysis
using
MATLAB
Deepak Malani, REC Calicut
Anant Malewar, IIT Bombay
Issued in public interest
by
Nex Robotics Pvt. Ltd.
(www.nex-robotics.com)
© Nex Robotics Pvt. Ltd.
http://www.nex-robotics.com/workshop.html
Foreword:
The wide area of vision based autonomous systems is broadly referred as machine vision. We have dealt with a beginner level module in this field, which we refer as vision-controlled motion (VCM). Keywords:

Machine Vision, Image acquisition, MATLAB, Vision based robot control 1
© Nex Robotics Pvt. Ltd.
http://www.nex-robotics.com/workshop.html
Table of Contents
1 Introduction______________________________________________________3 1.1 System Description:_________________________________________________3 1.2 Tools for Image Processing___________________________________________4 2 Getting started with MATLAB______________________________________5 2.1 MATLAB Interface__________________________________________________5 2.2 Working with Images________________________________________________6 2.2.1 Reading an image________________________________________________________6 2.2.2 Displaying an image______________________________________________________7 2.2.3 Generating an image_____________________________________________________9 2.3 M-files____________________________________________________________10 2.4 Functions__________________________________________________________12 3 Image Acquisition________________________________________________13 3.1 Previewing video___________________________________________________14 3.2 Capturing and storing images_______________________________________15 3.3 Getting ahead with Image Acquisition________________________________16 3.4 Interfacing with PC ports___________________________________________18 3.4.1 Parallel Port____________________________________________________________18 3.4.2 Serial Port______________________________________________________________19 4 Appendix_______________________________________________________21 4.1 Color Spaces_______________________________________________________21 5 References_______________________________________________________23 2

© Nex Robotics Pvt. Ltd.
http://www.nex-robotics.com/workshop.html
1 Introduction
In this section, an overview of vision controlled motion (VCM) as a system is explained. 1.1 System Description:
The system for VCM consists of:
1. Image acquisition setup: It consists of a video camera, web camera, or an analogue camera with suitable interface for connecting it to processor. 2. Processor: It consists of either a personal computer or a dedicated image processing unit. 3. Image analysis: Certain tools are used to analyze the content in the image captured and derive conclusions e.g. locating position of an object. 4. Machine control: After making the conclusion, mechanical action is to be taken e.g. Using serial or parallel port of a PC to control left and right motors of a robot to direct it towards the ball Pictorially, the system can be represented as:

Machine Control
e.g. Using parallel port to control left and right motors
Image Analysis Tool
e.g. MATLAB
Image Processor
e.g. PC, DSP
Image Acquisition
Device
e.g. CCD camera
1. Image capturing can be done using video camera available in various resolutions e.g. 640 x 480 pixels. There are two types of cameras generally available: Digital cameras (CCD – charge coupled device and CMOS sensor based) and analogue cameras. Digital cameras generally have a direct interface with computer (USB port), but analogue cameras require suitable grabbing card or TV tuner card for interfacing with PC. Power requirements: CCD cameras give high quality, low-noise images. It generates an analog signal and uses analog to digital converter (ADC) and thus consumes high power. CMOS cameras have lesser sensitivity resulting in poor image quality but consume lesser power resulting in more battery life. 2. Image analysis consists of...
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