1. Multimedia Specification Design and Production 2013 / Semester 2 / week 8 Lecturer: Dr. Nikos Gazepidis gazepidis@ist.edu.gr

2. 2 Outline  Human Computer Interface.  Multimedia interfaces and applications.  Vision based interfaces  Systems using vision based interfaces.  Some basic methods in vision interfaces Background subtraction. Color blob detection and tracking. Face detection (Viola and Jones face detector). Multimedia and HCI

3. 3 Human Computer Interface  Different meanings of HCI: 1.The study of people, computer technology and the ways they interactive with each other. 2.The design, evaluation and implementation of computer systems for human use. 3.The research to study how to make computer systems more use-able. Multimedia and HCI

4. 4 Aspects of HCI  Design Intuition, experiences and design principles.  Human factors Experiments testing the perception, memory and cognition models of human being.  Devices Physical devices such as mouse, keyboards and other fancy HCI hardware.  Software and systems Such as windows GUI, shell commands in Unix etc. Multimedia and HCI

5. 5 HCI Studies  Computers What are they good at and bad at? Input, output, processing, networking, etc.  People What are people good at? What is the limitation of human abilities? Input, output, memory, perception and cognition model. No average answer. Must accommodate diversities.  Usability More than the size of widgets, where are the buttons and syntax of commands.  Context Environment, physical constraints, cognition constraints, task, etc. Multimedia and HCI

6. 6 The quality of HCI  There are fives factors that affect the design and implementation of HCI Time to learn. Speed of performance. Rate of errors. Retention over time. Subjective satisfaction Multimedia and HCI

7. 7 Multimedia Interfaces  Multimedia interface combines different sorts of media modalities to achieve more natural and more efficient human computer communication. Speech, audio, touch, video input (patterns, posture, gesture) etc.  “Put that there” is an example multimedia HCI that combines speech, gestures and graphics Multimedia and HCI Put that there, MIT 1981 http://www.media.mit.edu/speech/sig_videos.html

8. 8 Advantages of Multimedia Interface  More alternative methods.  The flexibility of combining different schemes.  More efficient for specific tasks.  Greater precision of information.  Help handicapped people to use computers Multimedia and HCI http://www.youtube.com/watch?v=d7eGypGOlOc&feature=relatedhttp://www.youtube.com/watch?v=Gnq-8iaOcXk Pen gesture interface Virtual Reality

9. 9 Vision Based Interfaces  Vision based interfaces uses computer vision techniques to achieve more effective HCI.  Vision based interfaces are based on techniques such as: Multimedia and HCI Hand tracking, Hand gesture, Arm gesture Hand Pointing Face detection Head tracking Gaze Expression Lip reading Posture, body gesture and action recognition

10. 10 Example Systems Multimedia and HCI Motion Capturing

11. 11 Example Systems (cont.) Multimedia and HCI The MIT Kidsroom Posture recognition Action detection

12. 12 Methods in Vision Interfaces Multimedia and HCI  Background subtraction  Estimating the background B(n) = B(n)*alpha + I(n)*(1-alpha) Foreground Map = |Image – Background|>threshold alpha is a positive floating point number close to 1.

13. 13 Mean Shift Tracking Result Multimedia and HCI http://www.caip.rutgers.edu/~comanici/Papers/KernelTracking.pdf

14. 14 Viola and Jones face detector Multimedia and HCI  The Viola – Jones object detection framework is the first object detection framework to provide competitive object detection rates in real-time proposed in 2001 by Paul Viola and Michael Jones.  Although it can be trained to detect a variety of object classes, it was motivated primarily by the problem of face detection. This algorithm is implemented in OpenCV as cvHaarDetectObjects().

15. 15 Viola and Jones face detector (cont.) Multimedia and HCI These features can be computed using integral images similarly to the color histograms discussed before.

16. 16 Summary Multimedia and HCI  We only touch the very surface of multimedia interfaces.  Currently, the dominant HCI is still GUI with keyboard and mouse.  Multimedia interfaces are beginning to attract more and more interests.  We need more robust and efficient media recognition schemes to support effective multimedia interfaces.