CHIRP (algorithm)

CHIRP (Continuous High-resolution Image Reconstruction using Patch priors) is a Bayesian algorithm used to perform a deconvolution on images created in radio astronomy. The acronym was coined by lead author Katherine L. Bouman in 2016.[2][3]

First combined image reconstruction of the event horizon of a black hole (M87*) captured by the Event Horizon Telescope.[1]

The development of CHIRP involved a large team of researchers from MIT’s Computer Science and Artificial Intelligence Laboratory, the Center for Astrophysics | Harvard & Smithsonian and the MIT Haystack Observatory, including Bill Freeman and Sheperd Doeleman.[4][5] It was first presented publicly by Bouman at the IEEE Computer Vision and Pattern Recognition conference in June 2016.[2]

Development

The CHIRP algorithm was developed to process data collected by the very-long-baseline Event Horizon Telescope, the international collaboration that in 2019 captured the black hole image of M87* for the first time. CHIRP was not used to produce the image,[6] but was an algebraic solution for the extraction of information from radio signals producing data by an array of radio telescopes scattered around the globe.[3][7] Stable sources (that don't change over short periods of time) can also gain signal by integrating the change at each location with the rotation of the earth.[3]: 915  Because the radio telescopes used in the project produce vast amounts of data, which contain gaps, the CHIRP algorithm is one of the ways to fill the gaps in the collected data.[8][9]

Evaluation

For reconstruction of such images which have sparse frequency measurements the CHIRP algorithm tends to outperform CLEAN, BSMEM (BiSpectrum Maximum Entropy Method), and SQUEEZE, especially for datasets with lower signal-to-noise ratios and for reconstructing images of extended sources. While the BSMEM and SQUEEZE algorithms may perform better with hand-tuned parameters, tests show CHIRP can do better with less user expertise.[10]

See also

References
  1. Overbye, Dennis (April 10, 2019). "Black Hole Picture Revealed for the First Time – Astronomers at last have captured an image of the darkest entities in the cosmos". The New York Times. Retrieved April 10, 2019.
  2. Katherine L. Bouman, Michael D. Johnson, Daniel Zoran, Vincent L. Fish, Sheperd S. Doeleman, William T. Freeman (June 2016). "Computational Imaging for VLBI Image Reconstruction". IEEE Conference on Computer Vision and Pattern Recognition (CVPR). June 2016: 913–922. arXiv:1512.01413. Bibcode:2016cvpr.conf..913B – via Proceedings CVPR 2016 open access by Computer Vision Foundation.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  3. MIT News Office, Larry Hardesty (June 6, 2016). "A method to image black holes". MIT News.
  4. Shu, Catherine (April 11, 2019). "The creation of the algorithm that made the first black hole image possible was led by MIT grad student Katie Bouman". TechChrunch. Retrieved April 12, 2019.
  5. Brewis, Harriet (April 12, 2019). "Grad student Katie Bouman created the algorithm that led to the first-ever black hole photo". Evening Standard. Retrieved April 13, 2019.
  6. The Event Horizon Telescope Collaboration (2019). "First M87 Event Horizon Telescope Results. IV. Imaging the Central Supermassive Black Hole. Appendix A: Regularizer Definitions". The Astrophysical Journal. 875 (1): L4. arXiv:1906.11241. Bibcode:2019ApJ...875L...4E. doi:10.3847/2041-8213/ab0e85. hdl:10150/633752. S2CID 146068771.
  7. Science X, News Network (April 11, 2019). "Scientist superstar Katie Bouman designed algorithm for black hole image". PHYS.ORG. Retrieved April 13, 2019.
  8. Tech Desk, New Delhi (April 22, 2019). "This MIT grad student's work helped make the black hole event horizon image a reality". Express tech, The Indian Press. Retrieved April 13, 2019.
  9. ACM (Association for Computing Machinery), TechNews (June 6, 2016). "A Method to Image Black Holes". ACM News Service. Retrieved April 13, 2019.
  10. Kazunori Akiyama, Katherine L. Bouman, Andrew A. Chael, Michael D.Johnson, Sheperd S. Doeleman, Lindy Blackburn, John F. C. Wardle, William T. Freeman and the Event Horizon Telescope Collaboration, Vincent L. Fish (July 2017). "Observing—and Imaging—Active Galactic Nuclei with the Event Horizon Telescope". Galaxies. 4 (4): 54 and 64. doi:10.3390/galaxies4040054.{{cite journal}}: CS1 maint: multiple names: authors list (link)
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