Data compression is the technique to reduce the redundancies in data representation.
Data is represented as a combination of information and redundancy.
Information - Portion of data that mustbe preserved permanently in its origial form.
Redundancy- Portion of data that can be removed when it is not needed or resinserted when needed.
Compression: Reducing the redundant data from original data.
Decompression: Inserting the redundant data to recover the original data.
Compression Losses
- Lossy or lossless compression represents in compression of a file , all original data can be recovered when the file is uncompressed.
- In lossless compression, every bit remains after the file is uncompressed.
- Lossy compression reduces a file by elimininating certain information.
- Lossy compression is generally prefered to video and sound.
- In which certain amount of information loss will not be detected by most users.
Advantages of data compression:
- Reduces data storage requirements.
- Rich-quality signals for audio-visual data representation.
- Data security can be enhanced.
- Rate of input-output operations increase.
Disadvantages of data compression:
- Extra overhead incurred by encoding and decoding process.
- Reduces reliability of records.
- Tranmission of sensitive compressed data through noisy communication channel is very risky.
- Disruption of data properties in compression, result in data difference.
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