<p>STScI provides a <a href="https://stsci.app.box.com/v/jwst-simulated-psf-library" rel="nofollow noreferrer">library</a> of simulated point spread functions for each filter of each instrument of JWST and a tool to calculate the PSF yourself at any pixel location using the tool at <a href="https://www.stsci.edu/jwst/science-planning/proposal-planning-toolbox/psf-simulation-tool" rel="nofollow noreferrer">WebPSF</a>.</p>
<p>The most popular deconvolution algorithm seems to be the Lucy-Richardson iterative technique.  It must be used with caution because it produces erroneous artifacts when too many iterations are used.   There is also the Maximum Entropy Method (<a href="https://sparky.rice.edu/%7Ehartigan/irafmanuals/mem0b.pdf" rel="nofollow noreferrer">MEM</a>)</p>

CC BY-SA 4.0
2024-08-07T21:56:18.687Z
Perfect, thank you! I'm pretty amazed at the user-friendliness of the WebPSF site - I'll take an in-depth look this weekend. Also thanks for [Richardson–Lucy deconvolution](https://en.wikipedia.org/wiki/Richardson%E2%80%93Lucy_deconvolution) I've never deconvoluted anything in my life because I knew that in practice it's much harder than in principle, but with a nice formalism like that I *might* give it a try.
uhoh
CC BY-SA 4.0
2024-08-07T19:52:05.960Z
2024-08-07T19:52:05.960Z
eshaya
<p><a href="https://i.sstatic.net/Ngn84.jpg" rel="noreferrer"><img src="https://i.sstatic.net/Ngn84.jpg" alt="Shining like a brilliant beacon amidst a sea of galaxies, Arp 220 lights up the night sky in this view from the NASA/ESA/CSA James Webb Space Telescope https://esawebb.org/images/arp220a/" /></a></p>
<p>Source: <a href="https://esawebb.org/images/arp220a/" rel="noreferrer">Webb captures the spectacular galactic merger Arp 220</a></p>
<blockquote>
<p>Shining like a brilliant beacon amidst a sea of galaxies, Arp 220 lights up the night sky in this view from the NASA/ESA/CSA James Webb Space Telescope. Actually two spiral galaxies in the process of merging, Arp 220 glows brightest in infrared light, making it an ideal target for Webb. It is an ultra-luminous infrared galaxy (ULIRG) with a luminosity of more than a trillion suns. In comparison, our Milky Way galaxy has a much more modest luminosity of about ten billion suns.</p>
<p>Located 250 million light-years away in the constellation of Serpens, the Serpent, Arp 220 is the 220th object in Halton Arp’s Atlas of Peculiar Galaxies. It is the nearest ULIRG and the brightest of the three galactic mergers closest to Earth.</p>
<p>The collision of the two spiral galaxies began about 700 million years ago. It sparked an enormous burst of star formation. About 200 huge star clusters reside in a packed, dusty region about 5,000 light-years across (about 5 percent of the Milky Way’s diameter). The amount of gas in this tiny region is equal to all of the gas in the entire Milky Way galaxy.</p>
</blockquote>
<hr />
<p>By now most repeat-enjoyers of JWST's images are familiar with the pointy &quot;star&quot; patterns that appear at bright compact objects (generally individual bright stars) in JWST images produced by diffraction from various components of JWST's optics, including the hexagonal outline of JWST's primary and the spider mount for the secondary (as well as some internal optical elements on spider mounts sometimes I think).</p>
<p>However the center of the object <a href="https://en.wikipedia.org/wiki/Arp_220" rel="noreferrer">Arp 220</a> is a compact but still somewhat extended source of light (merging galaxies) and so the &quot;star&quot; diffraction pattern is fuzzy and the &quot;arms&quot; are pretty thick.</p>
<p>This object seems to be a good candidate to try to <a href="https://en.wikipedia.org/wiki/Deconvolution" rel="noreferrer">deconvolve</a> the image using the now very well characterized diffraction pattern of the telescope as the deconvolution kernel.</p>
<p><strong>Question:</strong> Is there a standard deconvolution procedure to remove JWST's diffraction pattern yet? If so, would Arp 220 be a good candidate on which to try it?</p>
<hr />
<p>Related:</p>
<ul>
<li><a href="https://astronomy.stackexchange.com/q/49862/7982">Why are diffraction spikes left in JWST public images?</a></li>
<li><a href="https://astronomy.stackexchange.com/q/11915/7982">What visual artifacts are expected from the JWST?</a></li>
<li><a href="https://astronomy.stackexchange.com/q/51994/7982">Why does one object (star?) in this JWST image have two sets of six+plus+two diffraction spikes but another, similar object nearby have only one?</a></li>
<li>some simulations in <a href="https://astronomy.stackexchange.com/a/48843/7982">this answer to <em>Why does the alignment evaluation image from JWST look like this?</em></a></li>
</ul>

CC BY-SA 4.0
2023-04-18T14:10:41.010Z
https://xkcd.com/2762/
Greg Miller
CC BY-SA 4.0
2023-06-14T02:13:58.997Z
https://www.aanda.org/articles/aa/full_html/2016/05/aa24003-14/aa24003-14.html maybe? I'm not terribly familiar with this kind of stuff XD
DialFrost
CC BY-SA 4.0
2023-06-14T04:31:14.887Z
@DialFrost that's an interesting paper about a method for deconvolution, but here I'm asking about JWST with it's very spiky - pointy - large point spread function (PSF) due to its' hexagonal aperture with sub hexagons, central obstruction and three secondary support arms - one of which adds two more spikes. It's a really challenging PSF to deconvolute, so I think it will need a more elaborate procedure tailored for JWST images.
uhoh
CC BY-SA 4.0
2023-06-14T12:58:55.443Z
Oh, my bad sorry, I'll keep looking
DialFrost
CC BY-SA 4.0
2024-06-19T15:45:02.787Z
That's a great idea. I don't think it would work because diffraction interference noise is still noise. You can subtract it, but you can't XOR it out and restore the damaged photons. Right? In the extreme case of a bright star filling the whole frame, you can't restore the galaxy wallpaper.
Miss Understands
CC BY-SA 4.0
2024-06-19T23:17:24.033Z
@Miss_Understands it will work *if you have a good model* for the diffraction pattern of a point source. That would be called a [point spread function](https://en.wikipedia.org/wiki/Point_spread_function) and deconvolution of a PSF is standard and essential in radio astronomy and optical and radar satellite imagery of Earth for example. Can you provide a link to a discussion of "damaged photons" so I can read further?
uhoh
CC BY-SA 4.0
2024-06-19T23:30:04.537Z
@Uhoh No, of course I can't. It just seems that, yes, in theory, you could invert the interference. But you'd have to sample the light at a ridiculously high spatial frequency and sense the intensity with ridiculously high number of  greyscale levels,
Miss Understands
CC BY-SA 4.0
2024-08-06T14:17:30.217Z
The PSF can be calculated for any filter at any pixel location using the tool at [WebPSF](https://www.stsci.edu/jwst/science-planning/proposal-planning-toolbox/psf-simulation-tool).
eshaya
CC BY-SA 4.0
2024-08-07T03:25:17.317Z
@eshaya Great! That's is literally the answer to my question, yay! I think you can add a one (or two) line answer post and I can accept it.
uhoh
<observational-astronomy><photography><james-webb-space-telescope><image-processing><post-processing>
Is there a standard deconvolution procedure to remove JWST's diffraction pattern yet? If so, would Arp 220 be a good candidate on which to try it?
uhoh
# Is there a standard deconvolution procedure to remove JWST's diffraction pattern yet? If so, would Arp 220 be a good candidate on which to try it?

(Asked by: username_0 on 2023-04-17)

[![Shining like a brilliant beacon amidst a sea of galaxies, Arp 220 lights up the night sky in this view from the NASA/ESA/CSA James Webb Space Telescope https://esawebb.org/images/arp220a/](https://i.sstatic.net/Ngn84.jpg)](https://i.sstatic.net/Ngn84.jpg)

Source: [Webb captures the spectacular galactic merger Arp 220](https://esawebb.org/images/arp220a/)

> Shining like a brilliant beacon amidst a sea of galaxies, Arp 220 lights up the night sky in this view from the NASA/ESA/CSA James Webb Space Telescope. Actually two spiral galaxies in the process of merging, Arp 220 glows brightest in infrared light, making it an ideal target for Webb. It is an ultra-luminous infrared galaxy (ULIRG) with a luminosity of more than a trillion suns. In comparison, our Milky Way galaxy has a much more modest luminosity of about ten billion suns.
>
> Located 250 million light-years away in the constellation of Serpens, the Serpent, Arp 220 is the 220th object in Halton Arp’s Atlas of Peculiar Galaxies. It is the nearest ULIRG and the brightest of the three galactic mergers closest to Earth.
>
> The collision of the two spiral galaxies began about 700 million years ago. It sparked an enormous burst of star formation. About 200 huge star clusters reside in a packed, dusty region about 5,000 light-years across (about 5 percent of the Milky Way’s diameter). The amount of gas in this tiny region is equal to all of the gas in the entire Milky Way galaxy.

---

By now most repeat-enjoyers of JWST's images are familiar with the pointy "star" patterns that appear at bright compact objects (generally individual bright stars) in JWST images produced by diffraction from various components of JWST's optics, including the hexagonal outline of JWST's primary and the spider mount for the secondary (as well as some internal optical elements on spider mounts sometimes I think).

However the center of the object [Arp 220](https://en.wikipedia.org/wiki/Arp_220) is a compact but still somewhat extended source of light (merging galaxies) and so the "star" diffraction pattern is fuzzy and the "arms" are pretty thick.

This object seems to be a good candidate to try to [deconvolve](https://en.wikipedia.org/wiki/Deconvolution) the image using the now very well characterized diffraction pattern of the telescope as the deconvolution kernel.

**Question:** Is there a standard deconvolution procedure to remove JWST's diffraction pattern yet? If so, would Arp 220 be a good candidate on which to try it?

---

Related:

* [Why are diffraction spikes left in JWST public images?](https://astronomy.stackexchange.com/q/49862/7982)
* [What visual artifacts are expected from the JWST?](https://astronomy.stackexchange.com/q/11915/7982)
* [Why does one object (star?) in this JWST image have two sets of six+plus+two diffraction spikes but another, similar object nearby have only one?](https://astronomy.stackexchange.com/q/51994/7982)
* some simulations in [this answer to *Why does the alignment evaluation image from JWST look like this?*](https://astronomy.stackexchange.com/a/48843/7982)

**Tags:** observational-astronomy, photography, james-webb-space-telescope, image-processing, post-processing
> **Comments:**
> **username_1**: https://xkcd.com/2762/  
> **username_2**: https://www.aanda.org/articles/aa/full_html/2016/05/aa24003-14/aa24003-14.html maybe? I'm not terribly familiar with this kind of stuff XD  
> **username_0**: @DialFrost that's an interesting paper about a method for deconvolution, but here I'm asking about JWST with it's very spiky - pointy - large point spread function (PSF) due to its' hexagonal aperture with sub hexagons, central obstruction and three secondary support arms - one of which adds two more spikes. It's a really challenging PSF to deconvolute, so I think it will need a more elaborate procedure tailored for JWST images.  
> **username_2**: Oh, my bad sorry, I'll keep looking  
> **username_3**: That's a great idea. I don't think it would work because diffraction interference noise is still noise. You can subtract it, but you can't XOR it out and restore the damaged photons. Right? In the extreme case of a bright star filling the whole frame, you can't restore the galaxy wallpaper.  
> **username_0**: @Miss_Understands it will work *if you have a good model* for the diffraction pattern of a point source. That would be called a [point spread function](https://en.wikipedia.org/wiki/Point_spread_function) and deconvolution of a PSF is standard and essential in radio astronomy and optical and radar satellite imagery of Earth for example. Can you provide a link to a discussion of "damaged photons" so I can read further?  
> **username_3**: @Uhoh No, of course I can't. It just seems that, yes, in theory, you could invert the interference. But you'd have to sample the light at a ridiculously high spatial frequency and sense the intensity with ridiculously high number of  greyscale levels,  
> **username_4**: The PSF can be calculated for any filter at any pixel location using the tool at [WebPSF](https://www.stsci.edu/jwst/science-planning/proposal-planning-toolbox/psf-simulation-tool).  
> **username_0**: @eshaya Great! That's is literally the answer to my question, yay! I think you can add a one (or two) line answer post and I can accept it.  

---

## 1 answers

### Answer by username_4 on 2024-08-07. Score: 2 | Accepted answer

STScI provides a [library](https://stsci.app.box.com/v/jwst-simulated-psf-library) of simulated point spread functions for each filter of each instrument of JWST and a tool to calculate the PSF yourself at any pixel location using the tool at [WebPSF](https://www.stsci.edu/jwst/science-planning/proposal-planning-toolbox/psf-simulation-tool).

The most popular deconvolution algorithm seems to be the Lucy-Richardson iterative technique. It must be used with caution because it produces erroneous artifacts when too many iterations are used. There is also the Maximum Entropy Method ([MEM](https://sparky.rice.edu/%7Ehartigan/irafmanuals/mem0b.pdf))

> **Comments:**
> **username_0**: Perfect, thank you! I'm pretty amazed at the user-friendliness of the WebPSF site - I'll take an in-depth look this weekend. Also thanks for [Richardson–Lucy deconvolution](https://en.wikipedia.org/wiki/Richardson%E2%80%93Lucy_deconvolution) I've never deconvoluted anything in my life because I knew that in practice it's much harder than in principle, but with a nice formalism like that I *might* give it a try.  

---

