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JBIG
JBIG is an early lossless image compression standard from the Joint Bi-level Image Experts Group, standardized as ISO/ IEC standard 11544 and as ITU-T recommendation T.82 in March 1993. It is widely implemented in fax machines. Now that the newer bi-level image compression standard JBIG2 has been released, JBIG is also known as JBIG1. JBIG was designed for compression of binary images, particularly for faxes, but can also be used on other images. In most situations JBIG offers between a 20% and 50% increase in compression efficiency over Fax Group 4 compression, and in some situations, it offers a 30-fold improvement. JBIG is based on a form of arithmetic coding developed by IBM (known as the Q-coder) that also uses a relatively minor refinement developed by Mitsubishi, resulting in what became known as the QM-coder. It bases the probability estimates for each encoded bit on the values of the previous bits and the values in previous lines of the picture. JBIG also supports prog ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
JBIG2
JBIG2 is an image compression standard for bi-level images, developed by the Joint Bi-level Image Experts Group. It is suitable for both lossless and lossy compression. According to a press release from the Group, in its lossless mode JBIG2 typically generates files 3–5 times smaller than Fax Group 4 and 2–4 times smaller than JBIG, the previous bi-level compression standard released by the Group. JBIG2 was published in 2000 as the international standard ITU T.88, and in 2001 as ISO/IEC 14492. Functionality Ideally, a JBIG2 encoder will segment the input page into regions of text, regions of halftone images, and regions of other data. Regions that are neither text nor halftones are typically compressed using a context-dependent arithmetic coding algorithm called the MQ coder. Textual regions are compressed as follows: the foreground pixels in the regions are grouped into symbols. A dictionary of symbols is then created and encoded, typically also using context-dependent a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
JBIG
JBIG is an early lossless image compression standard from the Joint Bi-level Image Experts Group, standardized as ISO/ IEC standard 11544 and as ITU-T recommendation T.82 in March 1993. It is widely implemented in fax machines. Now that the newer bi-level image compression standard JBIG2 has been released, JBIG is also known as JBIG1. JBIG was designed for compression of binary images, particularly for faxes, but can also be used on other images. In most situations JBIG offers between a 20% and 50% increase in compression efficiency over Fax Group 4 compression, and in some situations, it offers a 30-fold improvement. JBIG is based on a form of arithmetic coding developed by IBM (known as the Q-coder) that also uses a relatively minor refinement developed by Mitsubishi, resulting in what became known as the QM-coder. It bases the probability estimates for each encoded bit on the values of the previous bits and the values in previous lines of the picture. JBIG also supports prog ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Joint Bi-level Image Experts Group
The Joint Bi-level Image Experts Group (JBIG) is a group of experts nominated by national standards bodies and major companies to work to produce standards for bi-level image coding. The "joint" refers to its status as a committee working on both ISO and ITU-T standards. It is one of two sub-groups of ISO/IEC Joint Technical Committee 1, Subcommittee 29, Working Group 1 (ISO/IEC JTC 1/SC 29/WG 1), whose official title is ''Coding of still pictures''. The Joint Bi-level Image Experts Group created the JBIG and JBIG2 standards. The group often meets jointly with the JPEG committee, which typically meets three times annually. ISO/IEC JTC1 SC29 Working Group 1 (working together with ITU-T Study Group 16 – VCEG and previously also with Study Group 8 – SG8) is responsible for both JPEG and JBIG standards. It includes two sub-groups: the Joint Photographic Experts Group (JPEG SG) and the Joint Bi-level Image experts Group (JBIG SG). In the mid-1980s, both CCITT (now ITU ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Binary Image
A binary image is one that consists of pixels that can have one of exactly two colors, usually black and white. Binary images are also called ''bi-level'' or ''two-level'', Pixelart made of two colours is often referred to as ''1-Bit'' or ''1bit''. This means that each pixel is stored as a single bit—i.e., a 0 or 1. The names ''black-and-white'', ''B&W'', monochrome or monochromatic are often used for this concept, but may also designate any images that have only one sample per pixel, such as grayscale images. In Photoshop parlance, a binary image is the same as an image in "Bitmap" mode. Binary images often arise in digital image processing as masks or thresholding, and dithering. Some input/output devices, such as laser printers, fax machines, and bilevel computer displays, can only handle bilevel images. A binary image can be stored in memory as a bitmap, a packed array of bits. A 640×480 image requires 37.5 KiB of storage. Because of the small size of the ima ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ISO/IEC JTC 1/SC 29
ISO/IEC JTC 1/SC 29, entitled ''Coding of audio, picture, multimedia and hypermedia information'', is a standardization subcommittee of the Joint Technical Committee ISO/IEC JTC 1 of the International Organization for Standardization (ISO) and the International Electrotechnical Commission (IEC). It develops and facilitates international standards, technical reports, and technical specifications within the field of audio, picture, multimedia, and hypermedia information coding. The standards developed by SC 29 have been recognized by nine Emmy Awards. The international secretariat of SC 29 is the Japanese Industrial Standards Committee (JISC) of Japan. History ISO/IEC JTC 1/SC 29 was established in 1991, when the subcommittee took over the tasks of ISO/IEC JTC 1/SC 2/WG 8. Its title, "Coded representation of audio, picture, multimedia and hypermedia information", has not been changed since its inception. Within its first year, SC 29 established four working groups, a secretariat, and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lossless Data Compression
Lossless compression is a class of data compression that allows the original data to be perfectly reconstructed from the compressed data with no loss of information. Lossless compression is possible because most real-world data exhibits statistical redundancy. By contrast, lossy compression permits reconstruction only of an approximation of the original data, though usually with greatly improved compression rates (and therefore reduced media sizes). By operation of the pigeonhole principle, no lossless compression algorithm can efficiently compress all possible data. For this reason, many different algorithms exist that are designed either with a specific type of input data in mind or with specific assumptions about what kinds of redundancy the uncompressed data are likely to contain. Therefore, compression ratios tend to be stronger on human- and machine-readable documents and code in comparison to entropic binary data (random bytes). Lossless data compression is used in man ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Group 4 Compression
CCITT Group 4 compression, also referred to as G4 or Modified Modified READ (MMR), is a lossless method of image compression used in Group 4 fax machines defined in the ITU-T T.6 fax standard. It is only used for bitonal (black-and-white) images. Group 4 compression is based on the Group 3 two-dimensional compression scheme (G3-2D), also known as Modified READ, which is in turn based on the Group 3 one-dimensional compression scheme (G3), also known as Modified Huffman coding. Group 4 compression is available in many proprietary image file formats as well as standardized formats such as TIFF, CALS, CIT (Intergraph Raster Type 24) and the PDF document format. G4 offers a small improvement over G3-2D by removing the end-of-line (EOL) codes. G3 and G4 compression both treat an image as a series of horizontal black strips on a white page. Better compression is achieved when there are fewer unique black dots/lines on the page. Both G3-2D and G4 add a two-dimensional feature to ach ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lossy Compression Algorithms
In information technology, lossy compression or irreversible compression is the class of data compression methods that uses inexact approximations and partial data discarding to represent the content. These techniques are used to reduce data size for storing, handling, and transmitting content. The different versions of the photo of the cat on this page show how higher degrees of approximation create coarser images as more details are removed. This is opposed to lossless data compression (reversible data compression) which does not degrade the data. The amount of data reduction possible using lossy compression is much higher than using lossless techniques. Well-designed lossy compression technology often reduces file sizes significantly before degradation is noticed by the end-user. Even when noticeable by the user, further data reduction may be desirable (e.g., for real-time communication or to reduce transmission times or storage needs). The most widely used lossy compression al ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lossless Compression Algorithms
Lossless compression is a class of data compression that allows the original data to be perfectly reconstructed from the compressed data with no loss of information. Lossless compression is possible because most real-world data exhibits statistical redundancy. By contrast, lossy compression permits reconstruction only of an approximation of the original data, though usually with greatly improved compression rates (and therefore reduced media sizes). By operation of the pigeonhole principle, no lossless compression algorithm can efficiently compress all possible data. For this reason, many different algorithms exist that are designed either with a specific type of input data in mind or with specific assumptions about what kinds of redundancy the uncompressed data are likely to contain. Therefore, compression ratios tend to be stronger on human- and machine-readable documents and code in comparison to entropic binary data (random bytes). Lossless data compression is used in many ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
International Organization For Standardization
The International Organization for Standardization (ISO ) is an international standard development organization composed of representatives from the national standards organizations of member countries. Membership requirements are given in Article 3 of the ISO Statutes. ISO was founded on 23 February 1947, and (as of November 2022) it has published over 24,500 international standards covering almost all aspects of technology and manufacturing. It has 809 Technical committees and sub committees to take care of standards development. The organization develops and publishes standardization in all technical and nontechnical fields other than electrical and electronic engineering, which is handled by the IEC.Editors of Encyclopedia Britannica. 3 June 2021.International Organization for Standardization" ''Encyclopedia Britannica''. Retrieved 2022-04-26. It is headquartered in Geneva, Switzerland, and works in 167 countries . The three official languages of the ISO are English, F ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ISO Standards
The International Organization for Standardization (ISO ) is an international standard development organization composed of representatives from the national standards organizations of member countries. Membership requirements are given in Article 3 of the ISO Statutes. ISO was founded on 23 February 1947, and (as of November 2022) it has published over 24,500 international standards covering almost all aspects of technology and manufacturing. It has 809 Technical committees and sub committees to take care of standards development. The organization develops and publishes standardization in all technical and nontechnical fields other than electrical and electronic engineering, which is handled by the IEC.Editors of Encyclopedia Britannica. 3 June 2021.International Organization for Standardization" ''Encyclopedia Britannica''. Retrieved 2022-04-26. It is headquartered in Geneva, Switzerland, and works in 167 countries . The three official languages of the ISO are English, Fre ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ITU-T Recommendations
The ITU Telecommunication Standardization Sector (ITU-T) is one of the three sectors (divisions or units) of the International Telecommunication Union (ITU). It is responsible for coordinating standards for telecommunications and Information Communication Technology such as X.509 for cybersecurity, Y.3172 and Y.3173 for machine learning, and H.264/MPEG-4 AVC for video compression, between its Member States, Private Sector Members, and Academia Members. The first meeting of the World Telecommunication Standardization Assembly (WTSA), the sector's governing conference, took place on 1 March of that year. ITU-T has a permanent secretariat called the Telecommunication Standardization Bureau (TSB), which is based at the ITU headquarters in Geneva, Switzerland. The current director of the TSB is Chaesub Lee (of South Korea), whose first 4-year term commenced on 1 January 2015, and whose second 4-year term commenced on 1 January 2019. Chaesub Lee succeeded Malcolm Johnson of the Uni ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
