ComputerSSSSSSS

ComputerSSSSSSS

1. 1.8 Data Compression

   •  for the purpose of storing or transferring data use techniques data compression
   • Generic Data Compression Techniques
     • Lossless Lossy  Another lossless data compression technique is frequency-dependent encoding, a system in which the length of the bit pattern used to represent a data item is inversely related to the frequency of the item’s use. For example, less space is required to indi- cate that a bit pattern consists of 253 ones, followed by 118 zeros, followed by 87 ones than to actually list all 458 bits.
     • Lossless
       • schemes are those that do not lose information in the compression process. In cases where the data being compressed consist of long sequences of the same value, the compression technique called run-length encoding Another lossless data compression technique is frequency-dependent encoding
       • Huffman codes. As an example of frequency-dependent encoding, consider the task of encoded English language text. In the English language the letters e, t, a, and i are used more frequently than the letters z, q, and x. would be consecutive frames of amotion picture. In these cases, techniques using relative encoding, also known  as differential encoding
       • systems are based on dictionary encoding techniques. A variation of dictionary encoding is adaptive dictionary encoding (also known as dynamic dictionary encoding).  A popular example is Lempel-Ziv-Welsh (LZW) encoding (named after its creators, Abraham Lempel, Jacob Ziv, and Terry Welsh).
     • Lossy
       • schemes are those that do not lose information in the compression process.