lossy compression


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Related to lossy compression: Lossless compression

lossy compression

A compression technique that does not decompress digital data back to 100% of the original. Lossy methods can provide high degrees of compression and result in smaller compressed files, but some number of the original pixels, sound waves or video frames are removed forever. Examples are the widely used JPEG image, MPEG video and MP3 audio formats.

The greater the compression, the smaller the file. However, a high image compression loss can be observed in photos printed very large, and people with excellent hearing can notice a huge difference between MP3 music and high-resolution audio files (see audiophile). Typically, the moving frames of video can tolerate a greater loss of pixels than still images.

Lossy compression is never used for business data and text, which demand a perfect restoration (see lossless compression). See data compression, codec examples, JPEG, MPEG and MP3.


Lossless vs. Lossy Compression
Business data requires lossless compression, while audio and video applications can tolerate some loss, which may not be very noticeable.







Sometimes Hard to Tell
The top JPEG image is one fifth the file size of the bottom image, which was compressed the least. Look carefully at the orange section on the top of this cake.


Sometimes Hard to Tell
The top JPEG image is one fifth the file size of the bottom image, which was compressed the least. Look carefully at the orange section on the top of this cake.







Easier to See With Text
The top JPEG image was compressed the most, and the text is not as sharp as the least compressed. The bottom blow-up shows the distortion clearly.


Easier to See With Text
The top JPEG image was compressed the most, and the text is not as sharp as the least compressed. The bottom blow-up shows the distortion clearly.


Easier to See With Text
The top JPEG image was compressed the most, and the text is not as sharp as the least compressed. The bottom blow-up shows the distortion clearly.







Lossless GIFs Are Better for Text
The same text is saved in the lossless GIF format. Not only is it as sharp as the least-compressed JPEG, the GIF file is almost 1/10th the size.


Lossless GIFs Are Better for Text
The same text is saved in the lossless GIF format. Not only is it as sharp as the least-compressed JPEG, the GIF file is almost 1/10th the size.
References in periodicals archive ?
This selection represents that the compression carried out is lossy compression. Let K be the set of indices of the M selected coefficients and [f.sub.M] be the compression obtained.
SPARTAN [5] is a system that takes advantage of attribute semantics and data-mining models to perform lossy compression of massive data tables, which is based on the novel idea of exploiting predictive data correlations and prescribed error tolerances for individual attributes to construct concise and accurate Classification and Regression Tree (CaRT) models for entire columns of a table.
Given the data volume challenge we face, we should consider the wider use of more aggressive data compression techniques, such as lossy compression, as a matter of course.
As one more option of DI lossy compression implementation we will consider a way which is not the accepted standard, but it is often used during the work with images [10].
Lossless and lossy compression technique is applied on ROI and non-ROI parts respectively (Kaur et al., 2011).
This kind of compression is "lossy." While most of the modern compression algorithms, including JPEG, MP3, and MPEG-4, most commonly use lossy compression, they often also allow the user to choose the level of "loss." (8) The accompanying manuals and technical reports classify the results of the compression in various groups, which they give names like "very good" or "excellent quality" results.
Texture is encoded by lossy compression in a way similar to minimum description length (MDL) principle, but here the length of the data given the model is approximated by the number of samples times the entropy of the model.
However unlike PNG, WebP allows lossy compression of images with transparency.
Conversely, lossy compression does not allow for perfect reconstruction of the data, but has the advantage that much higher CRs can be obtained.
The video quality is influenced by two different types of distortion which arise, on the one hand, from the effects of lossy compression introduced by the source encoding (source distortion), and on the other hand, from the lossy transmission channel (loss distortion) [1].
Data compression methods can be divided into two categories: Lossless Compression methods without losing any part of the data and Lossy Compression methods.
Basic ideas of lossless and lossy compression algorithms are covered.