Image Stabilization

Discussions of using SharpCap for Planetary Imaging
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multiweb
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Image Stabilization

Post by multiweb » Fri Oct 16, 2020 5:03 am

Good day, first post here, I reside in Sydney west. I'm doing some planetary imaging with a TAK CN-212 and an ASI 426MC with a Baader FFC on a G11. FL is around 8m and focus can be quite challenging. I like Sharpcap very much. None of the focusing routine really work for me though. Contrast/Edge detection. I'm not even sure what I'm looking at. The histogram varies with the position of the planet in the fov as well. One neat feature FireCapture has is the option to create a bounding box and stabilise the ROI. That makes it so much easier to look at fine details and eyeball the focus. Sharpcap has already a panning feature for the ROI which is uber cool when capturing for small drifts and you don't have to bump the mount. So my question is, is there a way to stabilize that ROI while focusing to minimize the planet wobble? Thanks for any pointers.

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admin
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Re: Image Stabilization

Post by admin » Fri Oct 16, 2020 8:49 pm

Hi,

SharpCap 3.3 (currently in beta – check out the beta testing forum for discussions and download links) has a mode in the feature tracking system where it will track the centre of brightness of the image using the camera ROI. I think that comes pretty close to what you are after, but it is broken in the currently available build. I hope to have a new version uploaded sometime over the weekend that has a fix for this in it. This is a new feature, side be interested in feedback.

If you are trying to focus on a planetary target at high gain and high magnification then I believe that the contrast range measurement should be best – this is less affected by noise in the image. This has also been improved in SharpCap 3.3 to use a more robust algorithm. With this measurement, you are looking for the largest measurement values which indicate the best focus.

Cheers, Robin

multiweb
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Joined: Fri Oct 16, 2020 4:25 am

Re: Image Stabilization

Post by multiweb » Fri Oct 16, 2020 10:18 pm

No worries, thanks mate. Sounds great! I'll head there and download. Keen to test it.

multiweb
Posts: 6
Joined: Fri Oct 16, 2020 4:25 am

Re: Image Stabilization

Post by multiweb » Fri Oct 16, 2020 11:25 pm

Hi Robin, I downloaded the latest beta v3.3.6917.0 and had a quick look at the documentation and plugged in an ASI 462MC on a Window 10 system via USB3.0. I started the Tools>Feature Tracking (Experimental) process at high frame rate. That's the one you're working on I assume. Looks good. I see its primary use as is would be to bump the mount via an ASCOM driver. Standard calibration process setup boxes. Pretty neat. I also noticed the ROI option. Is that the one you're thinking of for high frequency corrections for seeing? Will wait for the fix and revisit. Thanks.

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Re: Image Stabilization

Post by admin » Sun Oct 18, 2020 2:49 pm

Hi,

yes, the ROI version was what I was thinking about for the higher speed correction. However I've been thinking about this a bit more and I think the right solution for the sort of use case you're talking about would be a realignment on a frame by frame basis to put the planet in the centre of the frame. This wouldn't actually use the camera ROI controls, it would just offset the image (filling any missing sections with black). I quite like that idea, so I'm going to investigate when I get a little time.

Cheers, Robin

multiweb
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Joined: Fri Oct 16, 2020 4:25 am

Re: Image Stabilization

Post by multiweb » Mon Oct 19, 2020 5:31 am

Excellent. Yes you already have the camera ROI so if you can link its position to the planet centroid and stabilize it at the same frame rate then it's going to make it much easier to focus.

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