Search results
Results From The WOW.Com Content Network
The DCT-II is an important image compression technique. It is used in image compression standards such as JPEG, and video compression standards such as H.26x, MJPEG, MPEG, DV, Theora and Daala. There, the two-dimensional DCT-II of blocks are computed and the results are quantized and entropy coded.
Many video encoders (such as DivX, Xvid, and 3ivx) and compression standards (such as MPEG-2 and H.264/AVC) allow custom matrices to be used. The extent of the reduction may be varied by changing the quantizer scale code, taking up much less bandwidth than a full quantizer matrix. [1] This is an example of DCT coefficient matrix:
An important development in image data compression was the discrete cosine transform (DCT), a lossy compression technique first proposed by Nasir Ahmed, T. Natarajan and K. R. Rao in 1973. [11] JPEG was introduced by the Joint Photographic Experts Group (JPEG) in 1992. [12]
The most common form of lossy compression is a transform coding method, the discrete cosine transform (DCT), [2] which was first published by Nasir Ahmed, T. Natarajan and K. R. Rao in 1974. [3] DCT is the most widely used form of lossy compression, for popular image compression formats (such as JPEG ), [ 4 ] video coding standards (such as ...
The macroblock is a processing unit in image and video compression formats based on linear block transforms, typically the discrete cosine transform (DCT). A macroblock typically consists of 16×16 samples, and is further subdivided into transform blocks, and may be further subdivided into prediction blocks.
This DCT, in the context of the family of discrete cosine transforms, is the DCT-II. It is the basis for the common JPEG image compression standard, [6] which examines small blocks of the image and transforms them to the frequency domain for more efficient quantization (lossy) and data compression.
Compression artifacts may intentionally be used as a visual style, sometimes known as "glitch art". Rosa Menkman's glitch art makes use of compression artifacts, [16] particularly the discrete cosine transform blocks (DCT blocks) found in most digital media data compression formats such as JPEG digital images and MP3 digital audio. [2]
DCT coding is a lossy block compression transform coding technique that was first proposed by Nasir Ahmed, who initially intended it for image compression, in 1972. [ 9 ] In 1974, Ali Habibi at the University of Southern California introduced hybrid coding, [ 10 ] [ 11 ] which combines predictive coding with transform coding.