Compression artifactA compression artifact (or artefact) is a noticeable distortion of media (including , audio, and video) caused by the application of lossy compression. Lossy data compression involves discarding some of the media's data so that it becomes small enough to be stored within the desired or transmitted (streamed) within the available bandwidth (known as the data rate or bit rate). If the compressor cannot store enough data in the compressed version, the result is a loss of quality, or introduction of artifacts.
Compression fractaleLa compression fractale est une méthode de encore peu utilisée aujourd’hui. Elle repose sur la détection de la récurrence des motifs, et tend à éliminer la redondance d’informations dans l'image. C'est une méthode destructive puisque l'ensemble des données de départ ne se retrouve pas dans l'image finale. Il existe plusieurs méthodes (subdivision de triangles, Delaunay etc.) mais la compression par la méthode Jacquin est la plus connue.
Bit fieldA bit field is a data structure that consists of one or more adjacent bits which have been allocated for specific purposes, so that any single bit or group of bits within the structure can be set or inspected. A bit field is most commonly used to represent integral types of known, fixed bit-width, such as single-bit Booleans. The meaning of the individual bits within the field is determined by the programmer; for example, the first bit in a bit field (located at the field's base address) is sometimes used to determine the state of a particular attribute associated with the bit field.
Hash chainA hash chain is the successive application of a cryptographic hash function to a piece of data. In computer security, a hash chain is a method used to produce many one-time keys from a single key or password. For non-repudiation, a hash function can be applied successively to additional pieces of data in order to record the chronology of data's existence. A hash chain is a successive application of a cryptographic hash function to a string .
