Sum of absolute transformed differences

Sum of absolute transformed differences

Sum of absolute transformed differences (SATD) is a widely used video quality metric used for block-matching in motion estimation for video compression. It works by taking a frequency transform, usually a Hadamard transform, of the differences between the pixels in the original block and the corresponding pixels in the block being used for comparison. The transform itself is often of a small block rather than the entire macroblock. For example, in x264, a series of 4×4 blocks are transformed rather than doing the more processor-intensive 16×16 transform.

Comparison to other metrics

SATD is much slower than the sum of absolute differences (SAD), both due to its increased complexity and the fact that SAD-specific MMX and SSE2 instructions exist, while there is no such instruction for SATD. However, it can still be optimized considerably with SIMD instructions on most modern CPUs. The benefit of SATD is that it more accurately predicts quality from both the standpoint of objective and subjective metrics. As such, it is often used in video compressors, either as an optional metric used in wide motion searches, such as in the Microsoft VC-1 encoder, or as a metric used in sub-pixel refinement, such as in x264.

ee also

*Hadamard transform
*Motion compensation
*Motion estimation
*Rate-distortion optimization
*Sum of absolute differences


*cite book | last = E. G. Richardson | first = Iain | title = H.264 and MPEG-4 Video Compression: Video Coding for Next-generation Multimedia | publisher = John Wiley & Sons Ltd. | date = 2003 | location = Chichester

Wikimedia Foundation. 2010.

Игры ⚽ Поможем сделать НИР

Look at other dictionaries:

  • Sum of absolute differences — (SAD) is a widely used, extremely simple video quality metric used for block matching in motion estimation for video compression. It works by taking the absolute value of the difference between each pixel in the original block and the… …   Wikipedia

  • Somme des différences absolues transformées — La Somme des différences absolues transformées ou SATD pour Sum of absolute transformed differences est un mesure très utilisée en compression vidéo pour évaluer la qualité vidéo d un bloc pendant l exécution de l estimation de mouvement. Cette… …   Wikipédia en Français

  • Algorithme de block-matching — Un algorithme de block matching ((en) Block Matching Algorithm) est une méthode utilisée pour encoder le mouvement dans une séquence vidéo en localisant des blocs similaires entre deux images. En compression vidéo, plusieurs normes vidéo telles… …   Wikipédia en Français

  • Estimation de mouvement — L estimation de mouvement ou Motion estimation(en) est un procédé qui consiste à étudier le déplacement des objets dans une séquence vidéo, en cherchant la corrélation entre deux images successives afin de prédire le changement de position du… …   Wikipédia en Français

  • Motion estimation — is the process of determining motion vectors that describe the transformation from one 2D image to another; usually from adjacent frames in a video sequence. It is an ill posed problem as the motion is in three dimensions but the images are a… …   Wikipedia

  • Rate–distortion optimization — (also RDO or RD) is a method of improving video quality in video compression. The name refers to the optimization of the amount of distortion (loss of video quality) against the amount of data required to encode the video, the rate . While it is… …   Wikipedia

  • Hadamard transform — The Hadamard transform (also known as the Walsh Hadamard transform, Hadamard Rademacher Walsh transform, Walsh transform, or Walsh Fourier transform) is an example of a generalized class of Fourier transforms. It is named for the French… …   Wikipedia

  • United Kingdom — a kingdom in NW Europe, consisting of Great Britain and Northern Ireland: formerly comprising Great Britain and Ireland 1801 1922. 58,610,182; 94,242 sq. mi. (244,100 sq. km). Cap.: London. Abbr.: U.K. Official name, United Kingdom of Great… …   Universalium

  • Germany — /jerr meuh nee/, n. a republic in central Europe: after World War II divided into four zones, British, French, U.S., and Soviet, and in 1949 into East Germany and West Germany; East and West Germany were reunited in 1990. 84,068,216; 137,852 sq.… …   Universalium

  • Europe, history of — Introduction       history of European peoples and cultures from prehistoric times to the present. Europe is a more ambiguous term than most geographic expressions. Its etymology is doubtful, as is the physical extent of the area it designates.… …   Universalium

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”