In information theory , an entropy coding (or entropy encoding ) is any lossless data compression method that attempts to approach the lower bound declared by Shannon's source coding theorem , which states that any lossless data compression method must have an expected code length greater than or equal to the entropy of the source.
18-456: JPEG XR ( JPEG extended range ) is an image compression standard for continuous tone photographic images, based on the HD Photo (formerly Windows Media Photo ) specifications that Microsoft originally developed and patented. It supports both lossy and lossless compression , and is the preferred image format for Ecma-388 Open XML Paper Specification documents. Support for the format
36-487: A Plug-in : The following APIs and software frameworks support JPEG XR and may be used in other software to provide JPEG XR support to end users: The 2011 video game Rage employs JPEG XR compression to compress its textures . .jxr are images created for hdr screenshots by [ xbox gamebar , nvidia shadowplay , obs , special k ]. once the image is out of it s original .jxr container, no software exists to remux back to .jxr again (jxrencapp.exe from jxrlib corrupts
54-541: A corrigendum approved in December 2009, and ISO/IEC issued a new edition with similar corrections on 30 September 2010. In 2010, after completion of the image coding specification, the ITU-T and ISO/IEC also published a motion format specification (ITU-T T.833 | ISO/IEC 29199-3), a conformance test set (ITU-T T.834 | ISO/IEC 29199-4), and reference software (ITU-T T.835 | ISO/IEC 29199-5) for JPEG XR. In 2011, they published
72-530: A Motion JPEG XR specification was approved as an ISO standard for motion (video) compression in March 2010. JPEG XR's design is conceptually very similar to JPEG : the source image is optionally converted to a luma-chroma colorspace, the chroma planes are optionally subsampled , each plane is divided into fixed-size blocks, the blocks are transformed into the frequency domain, and the frequency coefficients are quantized and entropy coded . Major differences include
90-728: A single compressed codestream.) Being TIFF-based, this format inherits all of the limitations of the TIFF format including the 4 GB file-size limit, which according to the HD Photo specification "will be addressed in a future update". New work has been started in the JPEG committee to enable the use of JPEG XR image coding within the JPX file storage format – enabling use of the JPIP protocol, which allows interactive browsing of networked images. Additionally,
108-773: A technical report describing the workflow architecture for the use of JPEG XR images in applications (ITU-T T.Sup2 | ISO/IEC TR 29199-1). JPEG XR is an image file format that offers several key improvements over JPEG , including: One file container format that can be used to store JPEG XR image data is specified in Annex A of the JPEG XR standard. It is a TIFF -like format using a table of Image File Directory (IFD) tags. A JPEG XR file contains image data, optional alpha channel data, metadata, optional XMP metadata stored as RDF/XML , and optional Exif metadata, in IFD tags. The image data
126-411: Is a contiguous self-contained chunk of data. The optional alpha channel, if present, can be compressed as a separate image record, enabling decoding of the image data independently of transparency data in applications which do not support transparency. (Alternatively, JPEG XR also supports an "interleaved" alpha channel format in which the alpha channel data is encoded together with the other image data in
144-456: Is the number of symbols in a code word, d {\displaystyle d} is the coding function, b {\displaystyle b} is the number of symbols used to make output codes and P {\displaystyle P} is the probability of the source symbol. An entropy coding attempts to approach this lower bound. Two of the most common entropy coding techniques are Huffman coding and arithmetic coding . If
162-659: The Joint Photographic Experts Group and Microsoft announced HD Photo to be under consideration to become a JPEG standard known as JPEG XR . On 16 March 2009, JPEG XR was given final approval as ITU-T Recommendation T.832 and starting in April 2009, it became available from the ITU-T in "pre-published" form. On 19 June 2009, it passed an ISO/IEC Final Draft International Standard (FDIS) ballot, resulting in final approval as International Standard ISO/IEC 29199-2 . The ITU-T updated its publication with
180-461: The approximate entropy characteristics of a data stream are known in advance (especially for signal compression ), a simpler static code may be useful. These static codes include universal codes (such as Elias gamma coding or Fibonacci coding ) and Golomb codes (such as unary coding or Rice coding ). Since 2014, data compressors have started using the asymmetric numeral systems family of entropy coding techniques, which allows combination of
198-425: The compression ratio of arithmetic coding with a processing cost similar to Huffman coding . Besides using entropy coding as a way to compress digital data, an entropy encoder can also be used to measure the amount of similarity between streams of data and already existing classes of data. This is done by generating an entropy coder/compressor for each class of data; unknown data is then classified by feeding
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#1732791076099216-473: The expected code length satisfies E x ∼ P [ ℓ ( d ( x ) ) ] ≥ E x ∼ P [ − log b ( P ( x ) ) ] {\displaystyle \operatorname {E} _{x\sim P}[\ell (d(x))]\geq \operatorname {E} _{x\sim P}[-\log _{b}(P(x))]} , where ℓ {\displaystyle \ell }
234-510: The file, and the other apis on this list when possible to export in .jxr corrupts the file as well). Microsoft has patents on the technology in JPEG XR. A Microsoft representative stated in a January 2007 interview that in order to encourage the adoption and use of HD Photo, the specification is made available under the Microsoft Open Specification Promise , which asserts that Microsoft allows implementation of
252-690: The following: The HD Photo bitstream specification claims that "HD Photo offers image quality comparable to JPEG-2000 with computational and memory performance more closely comparable to JPEG", that it "delivers a lossy compressed image of better perceptive quality than JPEG at less than half the file size", and that "lossless compressed images … are typically 2.5 times smaller than the original uncompressed data". A reference software implementation of JPEG XR has been published as ITU-T Recommendation T.835 and ISO/IEC International Standard 29199-5. The following notable software products natively support JPEG XR: The following notable software support JPEG XR through
270-534: The list of specifications covered by its Community Promise . In April 2013, Microsoft released jxrlib, an open source JPEG XR library under the BSD licence . This resolved any licensing issues with the library being implemented in software packages distributed under popular open source licences such as the GNU General Public License , with which the previously released "HD Photo Device Porting Kit"
288-492: The specification for free, and will not file suits on the patented technology for its implementation, as reportedly stated by Josh Weisberg, director of Microsoft's Rich Media Group. As of 15 August 2010, Microsoft made the resulting JPEG XR standard available under its Community Promise . In July 2010, reference software to implement the JPEG XR standard was published as ITU-T Recommendation T.835 and International Standard ISO/IEC 29199-5. Microsoft included these publications in
306-532: Was incompatible. Image compression Too Many Requests If you report this error to the Wikimedia System Administrators, please include the details below. Request from 172.68.168.226 via cp1108 cp1108, Varnish XID 257793133 Upstream caches: cp1108 int Error: 429, Too Many Requests at Thu, 28 Nov 2024 10:51:16 GMT Entropy encoding More precisely, the source coding theorem states that for any source distribution,
324-625: Was made available in Adobe Flash Player 11.0, Adobe AIR 3.0, Sumatra PDF 2.1, Windows Imaging Component , .NET Framework 3.0, Windows Vista , Windows 7 , Windows 8 , Internet Explorer 9 , Internet Explorer 10 , Internet Explorer 11 , Pale Moon 27.2. As of January 2021, there were still no cameras that shoot photos in the JPEG XR (.JXR) format. Microsoft first announced Windows Media Photo at WinHEC 2006, and then renamed it to HD Photo in November of that year. In July 2007,
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