期刊名称：International Journal of Advanced Research in Computer Engineering & Technology (IJARCET)
印刷版ISSN：2278-1323
出版年度：2016
卷号：5
期号：4
页码：1018-1020
出版社：Shri Pannalal Research Institute of Technolgy
摘要：The process of reducing the size of a data file is known as data compression. Compression can be of two types lossy or lossless. In lossless compression bits are reduced by identifying and eliminating redundancy. None information is lost in lossless compression and Lossy compression reduces bits by identifying unnecessary or redundant information and removing it. Data compression or bit-rate reduction involves encoding information using fewer bits than the original representation. In the context of data transmission, it is called source coding encoding done at the source of the data before it is stored or transmitted through network. Compression is of two types lossy or lossless. Lossless compression is preferred more than lossy for archival purposes and often for medical imaging, technical drawings, video clips, clip art, or comics and cartoon films. Lossy compression method is required especially when used at low bit rates , Lossy methods are especially suitable for natural images such as original photographs in applications where minor loss of accuracy is acceptable to achieve a substantial reduction in bit rate. The lossy compression which cannot identify differences may be called visually lossless. Compression is used because it helps reduce resource usage, like data storage space or transmission capacity. Compressed data must be decompressed to use, this extra process thrusts some computational or other costs through decompression method. Data compression is subject to a space¨Ctime complexity trade-off. For example, a compression scheme for video may requires expensive hardware for the video to be decompressed fast enough to be viewed as it is being decompressed, and the option to decompress the video in full it may be inconvenient or require additional storage. The design of data compression strategy involves trade-offs among various factors, including the degree of compression, the amount of distortion introduced.
