Hello.
Fairly new to Siril and getting to grips with it quite quickly but I can’t for the life of me figure out the Fourier transform to remove noise. I have tried searching online, YouTube etc for instructions before posting here but came up blank. Can anyone walk me through it please?
TIA.
Hello, have you seen this already?
https://free-astro.org/index.php?title=Siril:Manual#Fast_Fourier_Transform_.28FFT.29
I have but found it hard to follow as it is in French and no sound!
What kind of “noise” do you want to remove?
In fact, FFT remove patterns, not really noise that is random signal.
It’s the background of the image. Whilst it’s supposed to be black, it never actually is. I was hoping the fft would be able to remove it if given a sample to work with.
This will unlikely remove your bg. This tool is not dedicated for that.
Your background is probably full of noise, but the noise is something that is randomly distribute inside your image.
Transforming your image in the frequency range will not show you anything.
Are you attempting to produce renditions from single images? If so, I think you might be missing the point of Siril, being to stack multiple exposures in order to reduce noise. Getting more light from the scene is the best way to reduce noise in any photography, and especially challenging in astro, as there’s not a lot of light out there…
Or, are you stacking and still seeing noise? Might be useful if you would describe what you’re doing, and what you’re after.
I’ve stacked the images, circa 350 lights, 50 darks, biases, flats so the noise that remains is in the background and visible once stretched and gets more visible once the saturation is boosted. I was going to run the fft on the off chance it was a regular pattern or noise generated by the sensor or something (during debayering???) To see it the image could be improved. The lights were a mix of 1.6 and 2 second exposures (stacked with the appropriate darks etc) at 2000iso so I may simply by at the limits of what my kit is capable of.
That said, I would like to know how to use the feature!
One of the most important step you have to do during your session is the dither: https://skyandtelescope.org/astronomy-blogs/astrophotography-jerry-lodriguss/why-how-dither-astro-images/
It allows you to remove the huge amount of noise you could have in your background.
About the FFT process, the video we showed you (with no sound) presents the whole feature.
Even if the UI is in french, it is not too complicated to follow the different steps they are a few.
Thank you. I will practice both steps. Apparently the French video can have English subtitles so I’m sure I will be able to follow it.
Thanks again all for your advice