[研究生入学考试]中山大学软件工程移动信息工程专业课导论课件第三节.pdfVIP

Chapter 03 Chapter Goals • Distinguish between analog and digital information. • Explain data compression and calculate compression ratios. • Explain the binary formats for negative and floating-point values. • Describe the characteristics of the ASCII and Unicode character sets. 3-2 Chapter Goals • Perform various types of text compression. • Explain the nature of sound and its representation. • Explain how RGB values define a color. • Distinguish between raster and vector graphics. • Explain temporal and spatial video compression. 3-3 Data and Computers • Computers are multimedia devices, dealing with a vast array of information categories. Computers store, present, and help us modify • Numbers • Text • Audio • Images and graphics • Video 3-4 Data and Computers • Data compression Reduction in the amount of space needed to store a piece of data. • Compression ratio The size of the compressed data divided by the size of the original data. • A data compression techniques can be – lossless, which means the data can be retrieved without any loss of the original information, – lossy, which means some information may be lost in the process of compaction. 3-5 Analog and Digital Information • Computers are finite. Computer memory and other hardware devices have only so much room to store and manipulate a certain amount of data. The goal, is to represent enough of the w