Dithering

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robrj
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Dithering

Post by robrj » Tue May 02, 2017 10:26 pm

I see from the LRGB post that you're considering a sequence building and running feature. Would it be possible to dither using that feature?

Or perhaps it is something that could be done now via scripting (e.g. can the mount be moved a bit via a script)?

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admin
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Re: Dithering

Post by admin » Wed May 03, 2017 7:15 pm

I'll keep that in mind - certainly once there is a sequence builder it shouldn't be too hard to add new functions to it.

I guess though that for dithering to be needed you have to be guiding (if you're unguided then the drift will probably dither for you). If you just send a move command to the mount then PHD2 will correct it back straight away, so it's a bit more complicated. Still, I believe PHD has some sort of way to communicate with it, so not impossible.

cheers,

Robin

mAnKiNd
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Re: Dithering

Post by mAnKiNd » Sun Jun 11, 2017 4:58 pm

I love using sharpcap, but dithering with PHD2 is the only functionality I'm really really missing out on. I hope this can get implemented soon.

Cheers
Minos

jhbsky
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Re: Dithering

Post by jhbsky » Sun Jun 18, 2017 10:44 am

Hi
Love the UI and layout of Sharpcap.
Any possibility of an Automated Dithering feature.(controlling the PHD dither function)
I am a CMOS OSC user and correlation noise is a real downer.One can't seem to process out this noise (raining noise).
Dither is the only solution.
Any possibility of future implementation :?:
Otherwise i am a happy camper.
Cheers
Dave

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admin
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Re: Dithering

Post by admin » Mon Jun 19, 2017 6:27 am

Hi folks,

let me ask a question about this so that I understand more clearly what the requirement is...

Dithering is usually required when the tracking/guiding is so good that pixel artifacts (hot pixels, dead pixels, pixel noise etc) fall in the same position on on every sub frame. This would tend to imply either high end mounts costing $$$$$ or that you are guiding with PHD2 etc. Is that true?

Another reason I can think of for this request is that there is some image drift going on from sub-frame to sub-frame, and you are seeing patterns left in the live stack by the drift of various pixel noise like dead/hot pixels. An equally valid case, but might require a different solution.

Any further info appreciated.

cheers,

Robin

cuivenion
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Re: Dithering

Post by cuivenion » Mon Jun 19, 2017 6:30 pm

Hi Robin, as far as I am aware dithering is more important for OSC camera's or DSLR's. As you probably know dithering and a sigma stacking routine will get rid of hot pixels, planes and satellites trails. It also reduces the colour noise inherent in OSC and DSLR's. Someone called Tony Hallas has done a lot of work on this, he calls it 'colour mottle'.

https://www.youtube.com/watch?v=PZoCJBLAYEs#t=39

It would also remove the hot pixel smearing noise noise from image drift, but guiding should prevent that anyway. A lot of people think they get cleaner stacks with dithering and don't use darks. I imagine that woud be camera dependant though.

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