Nasir Ahmed (engineer)
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Nasir Ahmed | |
---|---|
Electrical Engineering | |
Thesis | |
Doctoral advisor | Shlomo Karni |
Nasir Ahmed (born 1940) is an Indian-American electrical engineer and computer scientist. He is
Discrete cosine transform (DCT)
The discrete cosine transform (DCT) is a lossy compression algorithm that was first conceived by Ahmed while working at the Kansas State University, and he proposed the technique to the National Science Foundation in 1972. He originally intended the DCT for image compression.[2][3] Ahmed developed a working DCT algorithm with his PhD student T. Natarajan and friend K. R. Rao in 1973,[2] and they presented their results in a January 1974 paper.[4][5][6] It described what is now called the type-II DCT (DCT-II),[7]: 51 as well as its inverse, the type-III DCT (a.k.a. IDCT).[4]
Ahmed was the leading author of the benchmark publication,[8][9] Discrete Cosine Transform (with T. Natarajan and K. R. Rao),[4] which has been cited as a fundamental development in many works[10] since its publication. The basic research work and events that led to the development of the DCT were summarized in a later publication by Ahmed entitled "How I came up with the Discrete Cosine Transform".[2]
The DCT is widely used for digital
Standard | Technologies |
---|---|
JPEG | Storage and transmission of photographic images on the World Wide Web (). |
MPEG-1 Video | Video distribution on CD or via the World Wide Web. |
H.262 ) |
Storage and handling of digital images in broadcast applications: digital TV, HDTV, cable, satellite, high speed internet; video distribution on DVD. |
H.261 | First of a family of video coding standards (1988). Used primarily in older video conferencing and video telephone products. |
H.263 | videoconferencing
|
The form of DCT used in signal compression applications is sometimes referred to as DCT-2 in the context of a family of discrete cosine transforms,[19] or as DCT-II.
More recent standards have used integer-based transforms that have similar properties to the DCT but are explicitly based on integer processing rather than being defined by trigonometric functions.[20] As a result of these transforms having similar symmetry properties to the DCT and being, to some degree, approximations of the DCT, they have sometimes been called "integer DCT" transforms. Such transforms are used for video compression in the following technologies pertaining to more recent standards. The "integer DCT" designs are conceptually similar to the conventional DCT but are simplified to provide exactly specified decoding with reduced computational complexity.
Standard | Technologies |
---|---|
VC-1 | Windows media video 9, SMPTE 421 .
|
H.264/MPEG-4 AVC |
The most commonly used format for recording, compression and distribution of high definition video; streaming internet video; Blu-ray Discs; HDTV broadcasts (terrestrial, cable and satellite). |
H.265/HEVC |
Successor to the H.264/MPEG-4 AVC standard having substantially improved compression capability. |
H.266/VVC |
Successor to HEVC having substantially improved compression capability. |
WebP Images | A graphic format that support the lossy compression of digital images. Developed by Google. |
WebM Video | A multimedia open source format intended to be used with HTML5. Developed by Google. |
A DCT variant, the
(OGG).The
Ahmed later was involved in the development a DCT lossless compression algorithm with Giridhar Mandyam and Neeraj Magotra at the University of New Mexico in 1995. This allows the DCT technique to be used for lossless compression of images. It is a modification of the original DCT algorithm, and incorporates elements of inverse DCT and delta modulation. It is a more effective lossless compression algorithm than entropy coding.[22]
Background
- Alumnus of the Bangalorein 1961;
- Received his M.S. and Ph.D. degrees in Electrical and Computer Engineering from the University of New Mexico in 1963 and 1966, respectively. His doctoral dissertation adviser was Shlomo Karni;
- Principal Research Engineer, Honeywell, St. Paul, Minnesota from 1966–68;
- Professor, Electrical and Computer Engineering Department, Kansas State University, 1968–83;
- 1983-2001: University of New Mexico—Presidential Professor of Electrical and Computer Engineering, 1983–89; Chair, Department of Electrical and Computer Engineering, 1989–94; Dean of Engineering, 1994–96; Associate Provost for Research and Dean of Graduate Studies, 1996–2001;
- Consultant, Sandia National Laboratories, Albuquerque, New Mexico, 1976–90.
- Married to Esther Parente-Ahmed. Son, Michael Ahmed Parente.
Books
- —; S2CID 10776771.
- —; Natarajan, T. Raj (1 March 1983). Discrete-Time Signals and Systems. S2CID 60330579.
Popular culture
In season 5, episode 8 of NBC's This Is Us, Ahmed's story was told to highlight the importance of image and video transmission over the Internet in modern society, particularly during the COVID-19 pandemic. The episode ends with a picture of Ahmed and his wife, along with captions explaining the importance of his work, and that producers spoke to the couple over video chat to understand their story and incorporate it into the episode.[23]
References
- ^ "Who is Nasir Ahmed? Real love story of Indian-American engineer on 'This Is Us' who is credited for .jpg algorithm". meaww.com. Retrieved 8 April 2022.
- ^ .
- .
- ^ S2CID 39023640.
- S2CID 12270940.
- CCITT. September 1992. Retrieved 12 July 2019.
- ^ S2CID 118873224.
- ^ Selected Papers on Visual Communication: Technology and Applications, (SPIE Press Book), Editors T. Russell Hsing and Andrew G. Tescher, April 1990, pp. 145-149 [1].
- ^ Selected Papers and Tutorial in Digital Image Processing and Analysis, Volume 1, Digital Image Processing and Analysis, (IEEE Computer Society Press), Editors R. Chellappa and A. A. Sawchuk, June 1985, p. 47.
- ^ DCT citations via Google Scholar [2].
- ^ Andrew B. Watson (1994). "Image Compression Using the Discrete Cosine Transform" (PDF). Mathematica Journal. 4 (1): 81–88.
- ^ image compression.
- ^ Transform coding.
- ..
- ^ CCITT 1992 [3].
- S2CID 56983045.
- ^ Yao Wang, Video Coding Standards: Part I, 2006
- ^ Yao Wang, Video Coding Standards: Part II, 2006
- .
- ^ Lee, Jae-Beom; Kalva, Hari (2008). The VC-1 and H.264 Video Compression Standards for Broadband Video Services. Springer Science+Business Media, LLC. pp. 217–245.
- ^ Guckert, John (Spring 2012). "The Use of FFT and MDCT in MP3 Audio Compression" (PDF). University of Utah. Retrieved 14 July 2019.
- S2CID 13894279.
- People.com. Retrieved 21 March 2022.
External links
- Nasir Ahmed publications indexed by Google Scholar
- IEEE Fellow in 1985, "for his contributions to engineering education and to digital signal processing" .[4].
- Distinguished Engineering Alumnus Award, University of New Mexico,2001.[5].
- Distinguished Graduate Faculty Member Award, Kansas State University, 1982-83.[6].