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JPEG, short for Joint Photographic Experts Group, is a globally recognized standard for digital image compression[1]. It was first published in 1992, and it’s a process of compressing digital images by reducing their file size without causing significant loss in image quality. This standard is embraced by numerous digital applications, such as digital cameras and online image storage. JPEG plays an instrumental role in the proliferation of digital images online, with billions of JPEG images created daily. Despite patent[2] controversies, JPEG remains the dominant image standard. Its file structure comprises different segments that contain distinct types of data crucial for encoding, decoding, and processing images. It’s essential to understand JPEG’s syntax and structure to handle images efficiently.

Définitions des termes
1. image compression. Image compression is a critical technique in digital technology, enabling efficient storage and transmission of images. This process involves reducing the size of an image file without significantly affecting its quality. Various techniques are used, including lossy and lossless methods, transform coding, color quantization, and more. The history of image compression dates back to the 1940s, with significant developments such as the introduction of the Discrete Cosine Transform in 1973 and the creation of JPEG in 1992. There are also progressive compression techniques that improve user experience by allowing images to load in stages. The field also encompasses issues such as JPEG copy protection, which seeks to prevent unauthorized use or alteration of images. Furthermore, there are various standards in image and other types of data compression, such as DEFLATE and JPEG2000 for images, H.261, H.262, H.263 for video, and G.711, G.726, G.729 for audio, which play a crucial role in ensuring interoperability.
2. patent. A patent is a form of legal protection for inventions, granting the inventor exclusive rights to use, produce, and sell their invention for a specific period. Originating from monarchial grants, patents have evolved through legal battles and significant milestones like the Venetian Patent Statute of 1474 and the Statute of Monopolies (1624). The patent system has gone through various changes, including the introduction of examination systems, changes in patentable subject matter, and a rise in global patent applications. Despite challenges such as validity disputes and infringement cases, patents remain crucial for protecting inventions. Enforcement is possible through civil lawsuits, with patent ownership possible for individuals, corporations, and even artificial intelligence systems. Patents play a significant role in licensing agreements, international treaties, and are governed by territorial laws and patent offices.
JPEG (Wikipedia)

JPEG (/ˈpɛɡ/ JAY-peg, short for Joint Photographic Experts Group) is a commonly used method of lossy compression pour digital images, particularly for those images produced by digital photography. The degree of compression can be adjusted, allowing a selectable tradeoff between storage size and image quality. JPEG typically achieves 10:1 compression with little perceptible loss in image quality. Since its introduction in 1992, JPEG has been the most widely used image compression standard in the world, and the most widely used digital image format, with several billion JPEG images produced every day as of 2015.

A photo of a European wildcat with the compression rate, and associated losses, decreasing from left to right
Filename extension
.jpg, .jpeg, .jpe
.jif, .jfif, .jfi
Internet media type
Type codeJPEG
Uniform Type Identifier (UTI)public.jpeg
Magic numberff d8 ff
Developed byJoint Photographic Experts Group, IBM, Mitsubishi Electric, AT&T, Canon Inc.
Initial releaseSeptember 18, 1992; 31 years ago (1992-09-18)
Type of formatLossy image compression format
Extended toJPEG 2000
StandardISO/IEC 10918, ITU-T T.81, ITU-T T.83, ITU-T T.84, ITU-T T.86
Site Edit this at Wikidata
Continuously varied JPEG compression (between Q=100 and Q=1) for an abdominal CT scan

Les Joint Photographic Experts Group created the standard in 1992. JPEG was largely responsible for the proliferation of digital images and photos numériques across the Internet and later médias sociaux.[circular reference] JPEG compression is used in a number of image file formats. JPEG/Exif is the most common image format used by digital cameras and other photographic image capture devices; along with JPEG/JFIF, it is the most common format for storing and transmitting photographic images on the World Wide Web. These format variations are often not distinguished and are simply called JPEG.

Les MIME media type for JPEG is "image/jpeg," except in older Internet Explorer versions, which provide a MIME type of "image/pjpeg" when uploading JPEG images. JPEG files usually have a filename extension of "jpg" or "jpeg". JPEG/JFIF supports a maximum image size of 65,535×65,535 pixels, hence up to 4 gigapixels for an aspect ratio of 1:1. In 2000, the JPEG group introduced a format intended to be a successor, JPEG 2000, but it was unable to replace the original JPEG as the dominant image standard.

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