Visit the following site then answer the questions below (in your blog)
1.What is data compression?
Data compression, source coding or bit-rate reduction is the process of encoding information using fewer bits than the original representation would use.
Compression is useful because
it helps reduce the consumption of expensive resources, such as hard disk space or transmission bandwidth
. On the downside, compressed data must be decompressed to be used, and this extra processing may be detrimental to some applications.
2.What is a data compression ratio?
Lossy image compression is used in digital cameras, to increase storage capacities with minimal degradation of picture quality. Similarly, DVDs use the lossy MPEG-2 Video codec for video compression.
I am not able to find the data compression ratio.
The compression ratio (that is, the size of the compressed file compared to that of the uncompressed file) of lossy video codecs is nearly always far superior to that of the audio and still-image equivalents.
- Video can be compressed immensely (e.g. 100:1) with little visible quality loss;
- Audio can often be compressed at 10:1 with imperceptible loss of quality;
- Still images are often lossily compressed at 10:1, as with audio, but the quality loss is more noticeable, especially on closer inspection.
The compression rate is 5 to 6 % in case of lossy compression while in case of lossless compression it is about 50 to 60 % of the actual file
3.Why is data compression an important technique for the online world
Lossy compression formats suffer from generation loss: repeatedly compressing and decompressing the file will cause it to progressively lose quality. This is in contrast with lossless data compression, where data will not be lost via the use of such a procedure. Therefore, data compression is an important technique for the online world, as to not loose information.
4.What is the difference between Lossy and Lossless data compression?
In information technology, "lossy" compression is a data encoding method which compresses data by discarding (losing) some of it. The procedure aims to minimise the amount of data that need to be held, handled, and/or transmitted by a computer.
Whereas ,
Lossless data compression is a class of data compression algorithms that allows the exact original data to be reconstructed from the compressed data. The term lossless is in contrast to lossy data compression, which only allows an approximation of the original data to be reconstructed, in exchange for better compression rates.
Therefore, Lossless data compression, retains all memory and data, but Lossy compression discards of losses some of it.
5.Which method offers the greatest compression ratio?
I would assume 'Lossy' compression, as discarding information, then compressing it the most.
6.Why is human psychology and perception an important factor in methods of Lossy compression?
To connect the discarded portions of information with the rest of the piece.
7.Name Lossy file formats for audio, still image and video format.
Lossy compression is most commonly used to compress multimedia data (audio, video, still images), especially in applications such as streaming media and internet telephony. By contrast, lossless compression is required for text and data files, such as bank records, text articles, etc. I am not certain of the exact format, as I could not locate it on the website.
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