Dithering Feature & Settings

Discussions, Bug Reports and Issues related to Beta versions of SharpCap
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LookoutLane
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Dithering Feature & Settings

Post by LookoutLane » Sun Aug 05, 2018 10:19 pm

Robin,

I was excited to see that 3.2 has automatic dithering and tested it last night with Live Stack. It seemed to work well except that it would often drop frames while waiting for the dither to settle even though it was only taking a few seconds at most to do so. The minimum settle time was set to 5 sec and the maximum was 60 seconds. I was imaging with 175 sec frames. My goal was to have it dither after each frame, but I wasn't sure what I should set the interval to. I tried 170s, 175s, and 180 sec intervals and then 350s to see if it made a difference eliminating dropped frames and I couldn't see that any of those changes to the interval setting made a difference in the dropped frames.

Any suggestions?

Scott

PS: Whenever I run Live Stack I always save the individual frames for DSS processing. Currently if Live Stack drops the frame it is not saved as an individual frame either. Would it be possible to add an option where the user could have it save all the individual frames whether Live Stack used them or not?

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admin
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Re: Dithering Feature & Settings

Post by admin » Mon Aug 06, 2018 6:08 am

Hi,

thanks for the feedback - the dropped frames after a dither is how it is supposed to work at the moment - SharpCap currrently runs all cameras in video mode meaning that new frames are started straight away after the previous frame finishes. Live stack starts a dither after stacking a frame, so the following frame will contain the dither movement and needs to be discarded to keep that out of the final stacked image.

I will see if I can work out a way to reliably reset the frame after the dither has completed, but that might be challengine across the whole range of supported cameras and may have to wait for SC3.3 and still camera mode support. For now I'd suggest using a dither interval that is several times the frame duration (shorter frames or longer dither) to reduce the problem.

cheers,

Robin

PilotAstronomy
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Re: Dithering Feature & Settings

Post by PilotAstronomy » Mon Aug 06, 2018 5:55 pm

Oh, one more piece of feedback (or perhaps I'm doing it wrong? I couldn't get this to work on the live version of SharpCap either).

I am trying to add dark and flat frames to my preprocessing, but when I select my masterdark or masterflat file I made (in Pixinsight) an error dialog comes up titled "Invalid Frame" with the text:

Frame could not be loaded.

C:\folder\folder\folder\filename.fit


And an "ok" button.

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Re: Dithering Feature & Settings

Post by admin » Mon Aug 06, 2018 6:33 pm

Hi,

please could you post the contents of your log and (if possible) a copy of the file that will not load. I expect that the problem is that the FIT file is using FIT features that SharpCap does not expect. As a workaround you could try saving as a 16 bit TIFF instead.

cheers,

Robin

PilotAstronomy
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Re: Dithering Feature & Settings

Post by PilotAstronomy » Mon Aug 06, 2018 6:45 pm

Lemme give that a try..... yup, that worked! Not sure what I did to the masterdark before but thanks!

Also, sorry about putting this in the wrong spot. You can delete it since it's off-topic. I got lost in my browser tabs.

LookoutLane
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Re: Dithering Feature & Settings

Post by LookoutLane » Sun Aug 12, 2018 9:46 pm

A question on the dither programming, couldn't you simply have the program pause the live stack during the dither or perhaps have a user-controlled setting that pauses the live stack for x seconds after a dither move? I know sometimes what seems simple to the user is actually very difficult to program and vice versa, but just thought I would ask.

In any case, I appreciate having the feature as is and I can certainly work around the dropped frame during the dither now that I know its that way by design rather than a bug or user error.

Scott

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Re: Dithering Feature & Settings

Post by admin » Tue Aug 14, 2018 3:23 pm

Hi Scott,

right now I don't have an easy way to stop the camera from running its continuous loop of frames that would work across all brands of camera. I thought about cutting the exposure down to (say) 0.1s during dithering and then re-adjusting back to the correct value once settled, but again some brands of camera don't reliably deliver the first frame correctly after an exposure change, so it all becomes complicated there too. The current way the code works is designed to be as safe as possible (in terms of not getting frames with movement into the stack). I do hope to improve the performance (in terms of wasted imaging time) in a future version though.

cheers,

Robin

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