Data compression ratio
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Data compression ratio is a computer term used to quantify the reduction in data quantity produced by a data compression algorithm. A data compression ratio is much like a physical compression ratio used to measure the physical compression of substances. Ratios are generally expressed as <original size>:<compressed size>.
A 10MB file that compresses to 2MB would have a 5:1 compression ratio.
Compression ratios are often given in percents. Percentage of compression is calculated by dividing the difference between size of source data and size of compressed data by size of source data. The 10MB file that compresses to 2 MB would have ((10-2)/10)*100% = 80% compression ratio.
Data compression ratios are also closely related to the concept of coding rates, which express the same concept but relate the ratio to more tangible quantities. For example, the coding rate of an audio stream may be expressed in "bits per second", or still image compression may be expressed in "bits per pixel". In many instances, coding rates can be converted to compression ratios if the physical characterstics of content of the original file are known. In contrast to compression ratios, lower coding rates indicate a higher level of compression.
External links
- Maximum Compression - Lossless data compression software benchmarks / comparisons