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**[[Radio frequency]] (RF) technology — [[RF engineering]], [[Aperture synthesis|aperture]] [[Sensor array|arrays]],<ref name="Ochoa"/> [[beamforming]], [[digital electronics|digital]] [[arithmetic circuit]]s, directional [[Sensor|sensing]], [[astronomical image processing|space imaging]]<ref>{{cite journal |last1=Potluri |first1=U. S. |last2=Madanayake |first2=A. |last3=Cintra |first3=R. J. |last4=Bayer |first4=F. M. |last5=Rajapaksha |first5=N. |title=Multiplier-free DCT approximations for RF multi-beam digital aperture-array space imaging and directional sensing |journal=Measurement Science and Technology |date=17 October 2012 |volume=23 |issue=11 |pages=114003 |doi=10.1088/0957-0233/23/11/114003 |s2cid=119888170 |issn=0957-0233}}</ref>
*[[Wireless sensor network]] (WSN) — wireless [[Surface acoustic wave sensor|acoustic sensor]] networks<ref name="Ochoa"/>
}}
===
The DCT-II
The integer DCT, an integer approximation of the DCT,<ref name="Britanak2010"/><ref name="Stankovic"/> is used in [[Advanced Video Coding]] (AVC),<ref name="Wang">{{cite journal |last1=Wang |first1=Hanli |last2=Kwong |first2=S. |last3=Kok |first3=C. |title=Efficient prediction algorithm of integer DCT coefficients for H.264/AVC optimization |journal=IEEE Transactions on Circuits and Systems for Video Technology |date=2006 |volume=16 |issue=4 |pages=547–552 |doi=10.1109/TCSVT.2006.871390|s2cid=2060937 }}</ref><ref name="Stankovic"/> introduced in 2003, and [[High Efficiency Video Coding]] (HEVC),<ref name="apple"/><ref name="Stankovic"/> introduced in 2013. The integer DCT is also used in the [[High Efficiency Image Format]] (HEIF), which uses a subset of the [[HEVC]] video coding format for coding still images.<ref name="apple"/> AVC uses
▲The DCT-II, also known as simply the DCT, is the most important [[image compression]] technique.{{citation needed|date=November 2019}} 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 <math>N \times N</math> blocks are computed and the results are [[Quantization (signal processing)|quantized]] and [[Entropy encoding|entropy coded]]. In this case, <math>N</math> is typically 8 and the DCT-II formula is applied to each row and column of the block. The result is an 8 × 8 transform coefficient array in which the <math>(0,0)</math> element (top-left) is the DC (zero-frequency) component and entries with increasing vertical and horizontal index values represent higher vertical and horizontal spatial frequencies.
▲The integer DCT, an integer approximation of the DCT,<ref name="Britanak2010"/><ref name="Stankovic"/> is used in [[Advanced Video Coding]] (AVC),<ref name="Wang">{{cite journal |last1=Wang |first1=Hanli |last2=Kwong |first2=S. |last3=Kok |first3=C. |title=Efficient prediction algorithm of integer DCT coefficients for H.264/AVC optimization |journal=IEEE Transactions on Circuits and Systems for Video Technology |date=2006 |volume=16 |issue=4 |pages=547–552 |doi=10.1109/TCSVT.2006.871390|s2cid=2060937 }}</ref><ref name="Stankovic"/> introduced in 2003, and [[High Efficiency Video Coding]] (HEVC),<ref name="apple"/><ref name="Stankovic"/> introduced in 2013. The integer DCT is also used in the [[High Efficiency Image Format]] (HEIF), which uses a subset of the [[HEVC]] video coding format for coding still images.<ref name="apple"/> AVC uses 4x4 and 8x8 blocks. HEVC and HEIF use varied block sizes between 4x4 and 32x32 [[pixels]].<ref name="apple"/><ref name="Stankovic"/> {{As of|2019}}, AVC is by far the most commonly used format for the recording, compression and distribution of video content, used by 91% of video developers, followed by HEVC which is used by 43% of developers.<ref name="Bitmovin">{{cite web |url=https://cdn2.hubspot.net/hubfs/3411032/Bitmovin%20Magazine/Video%20Developer%20Report%202019/bitmovin-video-developer-report-2019.pdf |title=Video Developer Report 2019 |website=[[Bitmovin]] |year=2019 |access-date=5 November 2019}}</ref>
====Image formats====
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