28-07-2012, 05:07 PM
Data Compression
Data Compression.pptx (Size: 139.91 KB / Downloads: 82)
Compression is a way to reduce the number of bits in a frame but retaining its meaning.
Decreases space, time to transmit, and cost
Technique is to identify redundancy and to eliminate it
If a file contains only capital letters, we may encode all the 26 alphabets using 5-bit numbers instead of 8-bit ASCII code
If the file had n-characters, then the savings = (8n-5n)/8n => 37.5%
Typical examples of application areas that are relevant to and motivated by data compression include:-
Personal communication systems such as facsimile, voice mail and telephony
Computer systems such as memory structures, disks and tapes
Mobile computing
Distributed computer systems
Computer networks, especially the Internet
Multimedia evolution, imaging, signal processing
Image archival and videoconferencing
Digital and satellite TV.
Types of compression
Compression schemes can be roughly divided into two classes:-
LOSSLESS COMPRESSION. Here we can’t afford to throw away any data at all: the compressed data must be completely recoverable. That is, the compression must be reversible.
Data Compression.pptx (Size: 139.91 KB / Downloads: 82)
Compression is a way to reduce the number of bits in a frame but retaining its meaning.
Decreases space, time to transmit, and cost
Technique is to identify redundancy and to eliminate it
If a file contains only capital letters, we may encode all the 26 alphabets using 5-bit numbers instead of 8-bit ASCII code
If the file had n-characters, then the savings = (8n-5n)/8n => 37.5%
Typical examples of application areas that are relevant to and motivated by data compression include:-
Personal communication systems such as facsimile, voice mail and telephony
Computer systems such as memory structures, disks and tapes
Mobile computing
Distributed computer systems
Computer networks, especially the Internet
Multimedia evolution, imaging, signal processing
Image archival and videoconferencing
Digital and satellite TV.
Types of compression
Compression schemes can be roughly divided into two classes:-
LOSSLESS COMPRESSION. Here we can’t afford to throw away any data at all: the compressed data must be completely recoverable. That is, the compression must be reversible.