A stunning new SHG image from Christian Buil

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A stunning new SHG image from Christian Buil

Post by thesmiths »

Christian Buil just posted a very impressive new spectroheliograph image over at http://www.astrosurf.com/topic/147294-s ... -la-fs128/. The image was a mosaic of 3 scans taken with a 128 mm telescope at 1040 mm focal length (FS128), using the SolEx SHG, a ASI 178 camera, done at 16x sidereal rate. There is a small gap where the scan overlap was not perfect.

Christian Buil June 27
Christian Buil June 27
cb_juin7_full3.jpg (1.43 MiB) Viewed 2039 times

The SolEx user community (around 100 members) seems very active in making both observational and computational progress. The nice weather in the south of France (to where many of them seem to have decamped) must also be accelerating their work.


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Re: A stunning new SHG image from Christian Buil

Post by marktownley »

That's nice!


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Re: A stunning new SHG image from Christian Buil

Post by Carbon60 »

Wow…stunning image. Thanks for sharing this impressive result.

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Re: A stunning new SHG image from Christian Buil

Post by Montana »

Wow!! that is the best I have ever seen, amazing resolution :bow :bow :bow

Alexandra


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Re: A stunning new SHG image from Christian Buil

Post by Merlin66 »

A very exciting image, from a great proponent of spectroscopy.
Christian’s recent Sol’Ex designed SHG is proving to be very popular. Valerie has also developed a processing package to support the instrument. The key parameters of narrow slit gaps and small pixel size cameras could revolutionize future SHG designs.
Maybe, at long last, the SHG is showing it’s real potential.


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Re: A stunning new SHG image from Christian Buil

Post by thesmiths »

Ken: I think the claim you made in your book "Imaging Sunlight" -- that the SHG images would equal or surpass the etalon in a few years -- is coming true. The high speed (USB 3), small pixel, large sensor cameras have changed everything (more or less a Moore's Law issue). The SolEx combination of a 2400 l/mm grating and a 10 micron wide slit with a 2.4 micron pixel camera gives it very good resolution -- despite the optics not really being so ideal. Software remains a weak link, although Valerie's inti algorithms are a big step forward.

In my contribution to your book, I pushed the idea that fast scanning should increase image quality and I notice Christian's recent work has all been done with fast scans of 16x (7.5 seconds). His experience is that with scans that short, you can get windows of stable seeing (at least in the early morning) that can last long enough to complete a full 7.5 sec scan. In this regard, NVMe SSD drives along with very large DDR4 DRAM buffering has also enabled very high FPS (another Moore's Law consequence).

My prediction is software coding using CUDA to enable GPU acceleration should allow essentially real-time image recreation.


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Re: A stunning new SHG image from Christian Buil

Post by p_zetner »

A very nice result.
I haven’t had much success making mosaics using the SHG. It’s certainly a route to very good spatial resolution.
Cheers.
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Re: A stunning new SHG image from Christian Buil

Post by MERRILL »

Amazing !!


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Re: A stunning new SHG image from Christian Buil

Post by thesmiths »

p_zetner wrote: Sat Jul 03, 2021 1:58 am A very nice result.
I haven’t had much success making mosaics using the SHG. It’s certainly a route to very good spatial resolution.
Christian is a bit of magician with software. I doubt though that many others can get the most out of the software which he wrote (particularly since the UI is all in French).


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Re: A stunning new SHG image from Christian Buil

Post by Merlin66 »

I contacted Valerie re her SHG software- it is really only usable to work with the SER files generated by the Sol’Ex.
Wash’s SLiM software I find is much more versatile and useful.


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Re: A stunning new SHG image from Christian Buil

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Merlin66 wrote: Tue Jul 13, 2021 9:08 pm I contacted Valerie re her SHG software- it is really only usable to work with the SER files generated by the Sol’Ex.
Wash’s SLiM software I find is much more versatile and useful.
Ken, I am working on a "fork" of Valerie's Solex Reconstruction (Solex_ser_recon) software from her GitHub. First, I have translated the input and output from French to English. Then made it more flexible to deal with a wider variety of acquisition scenarios. I also managed to speed it up by a factor of 5 to 10x by vectorising the calculations. I reduced the time to process one of Christian's SER files from the SolEx website (1.533 GB, 4461 frames) down to around 6 seconds (from 45 seconds with Valerie's original code). This includes construction of the image, implementing a flat, correcting for geometry, and doing a basic levels adjustment.

The typical 5GB (5000 frame) SER file from my SHG (in which I scan in both directions) takes about 14 seconds to fully process. The example below is a jpg version of the PNG output file -- with no additional image processing done to it:
my SHG image using modified Solex software
my SHG image using modified Solex software
161540_clahe.jpg (144.18 KiB) Viewed 1807 times
Below that is the same data processed using the SLiM software from Wah! (which, as I recall, took around a minute to process but does not do anything more than reconstruct the image):
my SHG data using Wah! software
my SHG data using Wah! software
161540_000.jpg (152.31 KiB) Viewed 1805 times
Valerie's code only works on SER files but it certainly works on my non-SolEx SHG. I will post my version to GitHub once it is cleaned up a bit and tested further (probably in the next week). It is far easier to work with than the software by Wah!, which requires a lot of manual fiddling around. This version of Valerie's software works pretty automatically. It will even will do batch processing of files.


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Re: A stunning new SHG image from Christian Buil

Post by Merlin66 »

Doug,
A very interesting development.
The speed and flexibility is a major step forward.
Look forward to trialling your final version.


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New SHG software now available for testing

Post by thesmiths »

Merlin66 wrote: Wed Jul 14, 2021 11:29 pm A very interesting development.
The speed and flexibility is a major step forward.
Look forward to trialling your final version.
Ken (and others): we have today pushed the preliminary English version to our GitHub:
https://github.com/thelondonsmiths/Solex_ser_recon_EN

I have written an extended explanation of the software here: viewtopic.php?f=33&t=32654

Paul (PDB) has trialled the new English version and confirms a significant reduction (approximately 6x) in processing time versus Valerie's original program.

The program is written in Python (Valerie's choice, not mine) which may not be everyone's cup of tea. But the new version gives reliable results and is now reasonably flexible -- and is really quite fast.


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Re: A stunning new SHG image from Christian Buil

Post by Merlin66 »

Doug,
Do you know why Valerie elected to only handle SER files, rather than AVI files?
I'm having "issues" with original AVI files converted to SER (using PIPP) being recognised.
Ken


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Re: A stunning new SHG image from Christian Buil

Post by PDB »

Ken,

Have you converted to 8bit or 16bit ser files?
If I look at Valéries codes I think it supports only 16 bit ser files for the moment.

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Re: A stunning new SHG image from Christian Buil

Post by thesmiths »

Merlin66 wrote: Fri Jul 16, 2021 1:28 am Do you know why Valerie elected to only handle SER files, rather than AVI files? I'm having "issues" with original AVI files converted to SER (using PIPP).
Ken
Valerie's code only works with SER files and it appears only with 16 bit ones. I checked conversion with PIPP and it converts 8bit to 8bit and 16bit to 16bit, mono to mono, etc. As for the reason why, I think it's because Christian believes 16 bit is essential and that SER is the future.


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Re: A stunning new SHG image from Christian Buil

Post by Merlin66 »

That makes some sense...
I've just checked, my AVI were converted to 8bit SER files in PIPP.
I'll try again tomorrow and see if they can be saved as 16 bit.


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Re: A stunning new SHG image from Christian Buil

Post by Merlin66 »

It appears that 8bit AVI files cannot be converted to 16 bit SER files.
(I have a few spectroheliograph files which I was going to use for "trials" in the INTI program, but these are all AVI!!)


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