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	Audio data compression - Wikipedia, the free encyclopedia
		Lossy compression typically achieves far greater compression than lossless compression (data of 5-20% of the original stream, rather than 50-60%), by simplifying the complexities of the data.
		Most lossy compression schemes allow compression parameters to be adjusted to achieve a target rate of data, usually expressed as a bit rate.
		Lossy formats are often used for the distribution of streaming audio, or interactive applications (such as the coding of speech for digital transmission in cell phone networks).
	en.wikipedia.org /wiki/Audio_data_compression (2160 words)

	A DATA COMPRESSION PRIMER --
		The right choice of compression tools and libraries for a particular application depends on the characteristics of the data and application in question: streaming versus file; expected patterns and regularities in the data; relative importance of CPU usage, memory usage, channel demands and storage requirements; and other factors.
		Lossy compression is a representation that allows you to reproduce something "pretty much like" the original data set.
		Lossy compression may be appropriate in these areas insofar as human observers do not perceive the literal bit-pattern of a digital image/sound, but rather more general "gestalt" features of the underlying image/sound.
	gnosis.cx /publish/programming/compression_primer.html (2692 words)

	Theory of Data Compression
		In lossy data compression, the decompressed data does not have to be exactly the same as the original data.
		Compression rate is the rate of the compressed data (which we imagined to be transmitted in ``real-time'').
		Compression ratio is the ratio of the size or rate of the original data to the size or rate of the compressed data.
	www.data-compression.com /theory.html (2876 words)

	Lossy data compression - Wikipedia, the free encyclopedia
		Lossy data compression is most commonly used to compress multimedia data (audio, video, still images) especially in applications, such as streaming media and internet telephony.
		The compression ratio (that is, the size of the compressed file compared to that of the uncompressed file) of lossy video codecs are nearly always far superior to those of the audio and still-image equivalents.
		Flaws caused by lossy compression that are noticeable to the human eye or ear are known as compression artifacts.
	en.wikipedia.org /wiki/Lossy_compression (906 words)

	Lossy Compression
		Lossy compression techniques recover the presentation with a certain loss of accuracy.
		These lossless compression techniques are suitable for wide range of applications, from hard disk file compression to digital medical image archiving, where data loss is usually not allowed.
		The important point of lossy compression is that, its compression procedure can be adjusted to sacrifice some accuracy in order to gain a lot of compression.
	www.csi.edu /support/itc/pres2/lossy.htm (395 words)

	Lossy compression - AMV (Site not responding. Last check: 2007-10-09)
		Lossy compression is the compression of a source with the loss of auditory or visual information.
		Many lossy compression algorithms are intended to minimize the detectability or salience of the loss of information.
		In AMV creation, lossy compression may be desirable for reducing bandwidth costs of distributing the video over the internet, and for meeting standardized compression requirements for some AMV contests.
	www.amvwiki.org /index.php/Lossy_compression (183 words)

	Lossless vs. lossy Compression (Site not responding. Last check: 2007-10-09)
		Lossless image compression is when the output of the encoding and decoding image process is the same.
		The main reason for lossy image compression is to free more disk space, which is used to save the image.
		Lossy and lossless image compression are based on the discrete cosine transform (mentioned on the last page), which allows compression to be achieved and produces a reconstructed image with the highest possible visual quality.
	www.amherst.edu /~gread08/page2.html (247 words)

	Lossless Wavelet Compression
		Predictive compression yields good results for image compression, where the change from pixel to pixel is not an entirely random process (assuming that the image is of something other than random noise).
		A lossy compression algorithm might be appropriate for the image compression used for Web page images, but it would be totally unacceptable for compressing the data from a chemistry experiment or a financial time series.
		Lossy compression also does not provide as good an estimate for calculating the amount of deterministic information in a time series, since some information has been discarded.
	www.bearcave.com /misl/misl_tech/wavelets/compression (3163 words)

	JBIG2 Primer - JBIG2: The Compression Connection
		Compression is the answer to a digital world that creates ever-increasing amounts of data.
		Simply stated, compression is the process of representing a set of data with a smaller set of data.
		In addition to differences in compression ratio, there can also be dramatic differences in both the speed of the encoding and in the latency of displaying and printing the compressed files.
	www.cvisiontech.com /jbig2_primer_compression_connection.html (1567 words)

	Lossy Compression
		Lossy compression is a typical engineering trade-off: lower image quality for lower transmission rate.
		For this reason, lossy compression is often evaluated with reference to a rate-distortion curve.
		Errors introduced by lossy compression of the lower level differences are retained and coded by higher-level DCT passes.
	www.stanford.edu /~mbax/ee392c/node6.html (870 words)

	Compression Techniques (Linktionary term)
		Lossy compression techniques are often "tunable" in that you can turn the compression up to improve throughput, but at a loss in quality.
		Compression can also be turned downed to the point at which there is little loss of image, but throughput will be affected.
		Compression is processor intensive, so for real-time data transmissions like network links, you will need a system on both ends of the link that can compress and decompress data without causing appreciable delays.
	www.linktionary.com /c/compression.html (4415 words)

	Lossy Compression
		Actually, lossy compression is normally very tricky and requires some higher math, but for this assignment we've provided the code for SVD decomposition algorithm.
		Obviously some files can be compressed much more than others, but even when they can't compress a file at all, both LZW and Huffman will still run, and the file they produce can always be decompressed to produce the original exactly.
		The compression algorithm we're using only works with one color component at a time, so when you extract the 128x128 chunks (or 8x8 chunck's in extra credit) of the image to pass to the SVD, you'll need to do this separately for the red, green, and blue components of the image.
	edbardsley.org /classes/15-211/lab4/lossy.html (2617 words)

	Bob Donlon’s Digital Video Blog: Manic Compression
		The whole idea behind compression is to lower the amount of data in the video in order to make its file size smaller, and/or make the data rate lower.
		DV compression is 5:1, meaning for every 5 bits of data, it only writes 1 to tape, throwing away the other 4.
		You could even extend the metaphor by saying that text that was compressed with a lossy method would end up garbled, since only the most significant letters of each word would be kept.
	blogs.adobe.com /bobddv/2006/09/manic_compression.html (1436 words)

	lossless and lossy compression - a Whatis.com definition
		Lossless and lossy compression are terms that describe whether or not, in the compression of a file, all original data can be recovered when the file is uncompressed.
		With lossless compression, every single bit of data that was originally in the file remains after the file is uncompressed.
		Lossy compression is generally used for video and sound, where a certain amount of information loss will not be detected by most users.
	whatis.techtarget.com /gDefinition/0,294236,sid5_gci214453,00.html (262 words)

	Lossy compression
		In JPEG compression, an image is transformed into spatial frequency form, and then the higher frequencies are eliminated or at least represented less accurately.
		If the compression is done judiciously, this process greatly reduces file size with little change that is visible to someone looking at the image resulting from decompressing the JPEG file.
		However, if the compression is carried too far, the resulting image is distorted with ripples.
	www.csc.calpoly.edu /~rtross/csc310/C3LossyCompression.htm (906 words)

	DataCompression.info - Lossy Compression (Site not responding. Last check: 2007-10-09)
		This category covers lossy compression methods that can't be pinned down to one of the more refined topics, such as JPEG or MP3.
		Compression is one of them, and there is certainly a great deal to learn about compression and media formats at this conference.
		While this isn't strictly a compression topic, it is obviously of critical importance to lossy compression techniques.
	datacompression.info /Lossy.shtml (390 words)

	Optimizing Web Graphics: Compression - webreference.com
		While the LZW compression algorithm used by GIFs is one of the better general purpose compression algorithms, it wasn't designed specifically for graphics.
		Compression and decompression times are symmetric, although the International JPEG Group's (IJG) decoder is more optimized and noticeably faster than their encoder.
		JPEG compression takes place in Y/UV space and therefore is treated as 24 bit data (8 bit for grey), regardless of the colors in the original image.
	www.webreference.com /dev/graphics/compress.html (3852 words)

	Halfbakery: Lossy Text Compression
		You can't compress letters, because they are the root, they are the fundemental particles or words, paragraphs, chapters, books, volumes.
		You can use lossy compression for JPEG's because that kind of visual information is handled by our right-brains which are holistic and relatively unaffected by loss of detail information--capable, indeed, of discerning meaning even in the face of awesomely unfavorable signal-to-noise ratios.
		Lossy compression is simply not appropriate for text compression because for the left brain to read the decompressed text, it must first work hard to "manufacture" the missing details (possibly calling on the right brain to step in and help?).
	www.halfbakery.com /idea/Lossy_20Text_20Compression (1023 words)

	Digital audio gets an audition: Part two: lossy compression - 1/18/2001 - EDN
		Compressed file sizes aren't meaningful comparison points for lossy-compression algorithms, because the objective is to always encode to a specific bit rate (Table 1).
		If temporal masking had occurred as part of lossy compression, you would see an interval with a reduced amplitude or a completely silent interval in the lossy-compression clips just prior to the onset of the "normal" audio material (at the 50-msec point in the original WAV file).
		Also note that all three lossy codecs appear to have preserved at least some of the channel-to-channel phase differences present in the original; one channel is a mirror image of the other.
	www.edn.com /article/CA74935.html (5624 words)

	Compression: Digital Imaging: Glossary: Learn: Digital Photography Review
		For instance, if you compress a document into a ZIP file and later extract and open the document, the content will of course be identical to the original.
		Lossy compression reduces the image size by discarding information and is similar to summarizing a document.
		JPEG is an image format that is based on lossy compression.
	www.dpreview.com /learn/?/Glossary/Digital_Imaging/Compression_01.htm (326 words)

	8. Compression
		Most compression software (or software-hardware packages) ask users to set the "quality" at a certain numerical value; the amount of compression actually delivered will vary from image to image, depending upon the image's characteristics.
		Depending on their intended use, images compressed with the JPEG algorithm by factors of as much as 25 to 1 or 30 to 1 can still be very useful, although artifacts created by the process may be visible.
		Compression of 10:1 was produced by "quality level" 20 in the system used for the preliminary samples; other systems may require different numerical settings.
	memory.loc.gov /ammem/pictel/mddp308.htm (1062 words)

	Bin Yu Lossy Data Compression
		This is called lossy compression and the theory studying its theoretical limits is called rate-distortion theory.
		Lossy compression is often done in practice, for example, when fetching images on the world wide web, recording audio on a compact disc or transmitting voice with a wireless digital telephone.
		This rate was asserted (for the distortion-rate function, which is the inverse of the rate-distortion function) in 1968 by Pilc, but his proof contained a major gap.
	www.stat.berkeley.edu /users/binyu/rdt.html (263 words)

	Lossy Compression
		Various digital image applications that require image compression do not allow error in the reconstructed image, thus lossless compression techniques are used.
		Applications such as astronomical imaging also require lossless compression, since the image is going to be processed by computing devices instead of human eyes.
		But as in lossless digital data compression, there is a trade-off of compression ratio for the error-free reconstruction.
	www.csi.edu /support/itc/pres2/lossless.htm (159 words)

	Definition: lossy compression (Site not responding. Last check: 2007-10-09)
		In video and multimedia, bit-rate reduction of an image signal by powerful algorithms that compress beyond what is achievable in lossless compression or in quasi-lossless compression.
		Note: Lossy compression accepts loss of information and introduction of artifacts that can be ignored as unimportant when viewed in direct comparison with the original.
		Lossy compression takes advantage of the subtended viewing angle for the intended display, the perceptual characteristics of human vision, the statistics of image populations, and the objectives of the display.
	www.atis.org /tg2k/_lossy_compression.html (142 words)

	Lossy Compression
		Difference between error free and lossy methods is the presence of a quantizer.
		Usually a scheme is used where a small number of bits are used to code error values near the peak of zero while larger numbers of bits are used for values farther from the peak.
		By far, the most popular transform for image compression is the DCT Indeed, the DCT is the basis of the JPEG international standard for color image compression.
	www.marquette.edu /~matthysd/web226/L0430.htm (303 words)

	Digital Compression
		In a lossy compression scheme, as the name implies, some of the original information is discarded when it is compressed.
		We are rapidly approaching the time when we won't need to compress the audio in order to save transmission time or conserve disk storage space.
		One proponent of Lossless Compression is Etree.org a music distribution hub but not for audio that has been compressed in a lossy fashion like MP3 or AAC but for audio that has been compressed in a lossless way.
	www.puredigitalaudio.org /digitalcompression/index.shtml (713 words)

	Lossy PNG (when it is implemented)
		PNG images are pixmaps compressed using Deflate compression, the same as used in zipfiles and by gzip.
		The greyscale image was compressed with 'dithering' enabled (set DITHER_LOSS true); for the colour image dithering was off because it doesn't yet correctly deal with neighbouring bytes representing different colours (a difference in red intensity cannot be carried across into the neighbouring green byte, but should affect the next pixel's red value).
		GIFiply is a lossy processor for images to increase their compressibility with GIF (which uses LZW compression, similar but inferior to the LZH used in PNG and zlib; the idea of string matching is in both though).
	membled.com /work/apps/lossy_png (1586 words)

	Lossy Compression
		Since the JPEG formulas are a “best fit” to the pixels that it starts with, rather than an exact fit, the pixels you started with won't be the same ones you end up with when you view the picture.
		The more compression, the smaller the file, but the less the accuracy.
		The moral of the story: you may wish to save your JPG files at various levels of compression; if a smaller file looks acceptable, use it.
	catcode.com /imgguide/lossy.html (173 words)

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