Lunar image processing.

[wouterdhoye]

Hi,

I made a little overview of the different steps in lunar image processing. The image was made on september 20th 2019 during a night with good to excellent seeing conditions.

First the capturing data: The image was captures with a CFF CC300f/20 classic cassegrain telescope. And a ZWO ASI 174MM camera at prime focus. As a filter a Baader orange filter was used. No additional optics were used.
The image scale is around 0,2" / pixel. A total of 3000 frames was captured.

The first image shown is a single frame randomly selected from the original 8bit SER file.

By itself the above image is not bad. plenty of detail is visible and it's quite sharp. If you'd inspect it closely though you will see that it is full of noise. At the size shown above it's hardly visible though.

First step in processing is stacking. I chose tot stack 20% of the frames. So 600 images. The main goals are: selecting the best frames, reducing noise. The result is quite dramatic. This step is indispensable when processing lunar images. open the image at high resolution tho see the difference. You will notice that overall more detail becomes visible.

the next step is deconvolution sharpening. For this purpose I use a Lucy richardsonn deconvolution. I used, because seeing was really good a rather small blur radius of between 1.5 and 2 pixels and about 30 iterations. The result is that more details become obvious. Just know one thing. don't overdo it. Too much sharpening will introduce artifacts also be cautious that you do not start to sharpen the background noise. (that's also a good reason too stack plenty of frames.)

final processing is done in Adobe Photoshop CC. Here the effect is most dramatic. techniques used are: high pass filters, unsharp mask, camera raw filter.

during the first three steps of processing the impact might seem subtle, and in fact is it subtle. However without those subtle changes it would be impossible to get the effects from the final processing. also during the final processing you'd constantly want to keep an eye on how noise behaves. Sometimes subtle noise reduction in between sharpening  steps might be necessary.

I hope this little guideline will come handy.

Clear skies,

Wouter.

[WestCoastCannuck]

Thanks much for this Wouter!   I do a similar process to you though I do some of your last step, in the third (unsharp mask, done in the same program as deconvolution, after).   I use AS!3, and then Astra Image or sometimes IMPPG.   My final touches I do in Lightroom.   I have thought before that Photoshop might do better given what I have seen, and now I am convinced.   I cannot make my file that looks like your third....  look like your last.   After many, many years as a digital photographer you would think I would know how to use PS, but I don't.   Perhaps, this post of yours may finally convince me to learn the beast.  (I know nothing of levels and curves....  and "high pass" filters!!)

Again, thanks much!!

 

Clear Skies!!

 

Mike

Edited March 1, 2020 by WestCoastCannuck
correction

[PembrokeSteve]

Hi Wouter ,

Many thanks for your time in providing such a useful overview.

The Lucy Richardson Deconvolution, is something I at present do not do, and this interests me greatly.
I went and "googled"  Lucy Richardson Deconvolution,  and then viewed the "Wikipedia" page of information, on this subject.
It showed a free software called "Raw Therapee" , ( I assume one can do deconvolution using this? ) which I downloaded.
Wow!  this free download seems too good to be true.
Does anyone else use this software, which seems very comprehensive in what it can do in regards to noise reduction, sharpening etc.
I am a bit suprized that I have never heard about it before.

Regards,

Steve

[Merlin66]

On 29/02/2020 at 23:17, wouterdhoye said:

Lucy richardsonn deconvolution

AstroArt has the LRD as well as many other filtering options.......http://www.msb-astroart.com/

Try the demo version to check it out.