tailieunhanh - Lecture BSc Multimedia - Chapter 9: Basic compression algorithms

Chapter 9: Basic compression algorithms. The following will be discussed in this chapter: Modeling and compression, basics of information theory, entropy example, Shannon’s coding theorem, compression in multimedia data, lossless vs lossy compression,. | CM3106 Chapter 9 Basic Compression Algorithms Prof David Marshall and Dr Kirill Sidorov School of Computer Science Informatics Cardiff University UK Modeling and Compression We are interested in modeling multimedia data. To model means to replace something complex with a simpler shorter analog. Some models help understand the original phenomenon data better Example Laws of physics Huge arrays of astronomical observations . Tycho Brahe s logbooks summarised in a few characters . Kepler Newton jFj _ gM1 M2 r2 . This model helps us understand gravity better. Is an example of tremendous compression of data. We will look at models whose purpose is primarily compression of multimedia data. CM3106 Chapter 9 Basic Compression Compression Overview 1 Recap The Need for Compression Raw video image and audio files can be very large. Example One minute of uncompressed audio. Audio Type KHz KHz KHz 16 Bit Stereo MB MB MB 16 Bit Mono MB MB MB 8 Bit Mono MB MB 630 KB Example Uncompressed images. Image Type File Size 512 x 512 Monochrome MB 512 x 512 8-bit colour image MB 512 x 512 24-bit colour image MB CM3106 Chapter 9 Basic Compression Compression Overview