CHIRP (Continuous High-resolution Image Reconstruction using Patch priors) is a Bayesian
Thomas Bayes (/beɪz/; c. 1701 – 1761) was an English statistician, philosopher, and Presbyterian minister.
Bayesian () refers either to a range of concepts and approaches that relate to statistical methods based on Bayes' theorem, or a follower ...
algorithm
In mathematics and computer science, an algorithm () is a finite sequence of rigorous instructions, typically used to solve a class of specific problems or to perform a computation. Algorithms are used as specifications for performing ...
used to perform a deconvolution
In mathematics, deconvolution is the operation inverse to convolution. Both operations are used in signal processing and image processing. For example, it may be possible to recover the original signal after a filter (convolution) by using a de ...
on images created in radio astronomy
Radio astronomy is a subfield of astronomy that studies celestial objects at radio frequencies. The first detection of radio waves from an astronomical object was in 1933, when Karl Jansky at Bell Telephone Laboratories reported radiation comi ...
. The acronym was coined by lead author
In academic publishing, the lead author or first author is the first named author of a publication such as a research article or audit.
Academic authorship standards vary widely across disciplines. In many academic subjects, including the natural ...
Katherine L. Bouman in 2016.
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
The Massachusetts Institute of Technology (MIT) is a private land-grant research university in Cambridge, Massachusetts. Established in 1861, MIT has played a key role in the development of modern technology and science, and is one of the ...
Haystack Observatory
Haystack Observatory is a multidisciplinary radio science center, ionospheric observatory, and astronomical microwave observatory owned by Massachusetts Institute of Technology (MIT). It is located in Westford, Massachusetts (US), approximate ...
, including Bill Freeman and Sheperd Doeleman
Sheperd "Shep" S. Doeleman (born 1967) is an American astrophysicist. His research focuses on super massive black holes with sufficient resolution to directly observe the event horizon. He is a senior research fellow at the Center for Astrophysic ...
. It was first presented publicly by Bouman at the IEEE Computer Vision and Pattern Recognition conference in June 2016.
Development
The CHIRP algorithm was developed to process data collected by the very-long-baselineEvent Horizon Telescope
The Event Horizon Telescope (EHT) is a large telescope array consisting of a global network of radio telescopes. The EHT project combines data from several very-long-baseline interferometry (VLBI) stations around Earth, which form a combined ...
, the international collaboration that in 2019 captured the black hole image of M87*
Messier 87 (also known as Virgo A or NGC 4486, generally abbreviated to M87) is a supergiant elliptical galaxy with several trillion stars in the constellation Virgo. One of the largest and most massive galaxies in the local uni ...
for the first time. CHIRP was not used to produce the image, 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. 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. 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.
Evaluation
For reconstruction of such images which have sparse frequency measurements the CHIRP algorithm tends to outperformCLEAN
Clean may refer to:
* Cleaning, the process of removing unwanted substances, such as dirt, infectious agents, and other impurities, from an object or environment
* Cleanliness, the state of being clean and free from dirt
Arts and media Music Al ...
, 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.
See also
*References
{{reflist Radio astronomy