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Motion-compensated DCT later became the standard coding technique for video compression from the late 1980s onwards. [18] [19] A DCT variant, the modified discrete cosine transform (MDCT), was developed by John P. Princen, A.W. Johnson and Alan B. Bradley at the University of Surrey in 1987, [20] following earlier work by Princen and Bradley in ...
Transform coding is a type of data compression for "natural" data like audio signals or photographic images. The transformation is typically lossless (perfectly reversible) on its own but is used to enable better (more targeted) quantization , which then results in a lower quality copy of the original input ( lossy compression ).
In more modern macroblock-based video coding standards such as H.263 and H.264/AVC, transform blocks can be of sizes other than 8×8 samples. For instance, in H.264/AVC main profile, the transform block size is 4×4. [4] In H.264/AVC High profile, the transform block size can be either 4×4 or 8×8, adapted on a per-macroblock basis. [4]
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 modified discrete cosine transform (MDCT) is a transform based on the type-IV discrete cosine transform (DCT-IV), with the additional property of being lapped: it is designed to be performed on consecutive blocks of a larger dataset, where subsequent blocks are overlapped so that the last half of one block coincides with the first half of the next block.
In addition to spectral analysis of signals, discrete transforms play important role in data compression, signal detection, digital filtering and correlation analysis. [2] The discrete cosine transform (DCT) is the most widely used transform coding compression algorithm in digital media, followed by the discrete wavelet transform (DWT).
Motion compensation is one of the two key video compression techniques used in video coding standards, along with the discrete cosine transform (DCT). Most video coding standards, such as the H.26x and MPEG formats, typically use motion-compensated DCT hybrid coding, [1] [2] known as block motion compensation (BMC) or motion-compensated DCT (MC ...
Block-artifacts are a result of the very principle of block transform coding. The transform (for example the discrete cosine transform) is applied to a block of pixels, and to achieve lossy compression, the transform coefficients of each block are quantized. The lower the bit rate, the more coarsely the coefficients are represented and the more ...