AS3 question

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Ivan
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AS3 question

Post by Ivan »

Hello everyone,

Has anyone faced an issue in AS3 where alignment points do not see the background? What could be the problem?
Thank you.

Ivan
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Re: AS3 question

Post by Montana »

What do you mean, what you have on screen is perfect. You don't want alignment points on the black space as there is nothing there.

Sometimes it doesn't pick up the prominences, then adjust the Min Bright up and down with the arrows, then replace AP grid.

I hope this helps?


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Re: AS3 question

Post by EGRAY_OBSERVATORY »

Exactly as Alexandra has just said Ivan.

Some prominences are not bright enough to be included with the brighter surface detail..

Terry


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Re: AS3 question

Post by Ivan »

Montana wrote: Thu Jul 15, 2021 10:43 am What do you mean, what you have on screen is perfect. You don't want alignment points on the black space as there is nothing there.

Sometimes it doesn't pick up the prominences, then adjust the Min Bright up and down with the arrows, then replace AP grid.

I hope this helps?
Many thanks to Alexandra,

Usually the alignment points are set all over the frame, even where the background is. But today there were no points there. I quickly folded it up and made sure the prominences were okay. I just wanted to know how it can be changed. And your answer helped me a lot, thanks again.

Ivan
Last edited by Ivan on Thu Jul 15, 2021 3:27 pm, edited 1 time in total.


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Re: AS3 question

Post by MAURITS »

I place always the min bright on 30.


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Re: AS3 question

Post by Rusted »

MAURITS wrote: Thu Jul 15, 2021 12:17 pm I place always the min bright on 30.
I have never really understood what this does.
Nothing seems to happen when it is adjusted.


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Re: AS3 question

Post by Montana »

Rusted, you will only notice it on limb shots, not on surface shots. Although I did do a test once and it did make a difference on the surface but I can't remember what :)

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Re: AS3 question

Post by MalVeauX »

Hi,

Lower the minimum brightness value. Yours is at 10. If you drop to 5 and re-place the AP's, maybe you will see it capture all that data in the shadow portion of the histogram that you cannot see on your monitor but exists in the data (ie, feint proms). That box tells AS!3 the minimum value on the histogram to consider signal. In our case with solar, any light is signal pretty much, so it's ok to just stack the entire FOV if you want, with a much lower min brightness.

There's no magic number for any of it, it really should reflect the data and what you're asking AS!3 to do with it.

It helps to know what and why this stuff is doing what it's doing. First, the AP's (alignment points) are actually a grid of pixel size boxes that will look at the local data inside the box only (hence local AP) and across all frames involved in the process. It will take the best data from each from in that box only and align & stack it to make a small box that has the best content. It will do this for all those boxes. Then, it will re-combine all these little boxes with the best data for each box from each frame(s) and re-combine them into a mosaic. The end result is a mosaic. Not just a few frames stacked. It's data from many frames sorted, re-combined as a mosaic. So the final image may have data from only some parts of some of the frames. This is how it produces a (usually) better result from lucky imaging in bad seeing.

So, you may want to have those AP's all over the FOV if you think there are proms in the shadows. If you do not have AP's out in the black space, you will not have those areas aligned and stacked and so the result on those proms may be poor. There's no detriment to stacking the black space by lowering your min brightness, if you think there is data there, it will not harm your disc. If you're worried about artifact at the limb due to stacking, use multi-scale on AP size (last check box on bottom), specifically for the limb as it will then look at smaller box data and larger box data in the same area to get a better mosaic re-combination to avoid artifact.

The AP size matters a lot. For fine details with lots of action, you may find smaller AP size works better to avoid big artifact with the alignment process for re-combining the AP boxes as a mosaic. Smaller ones will align with less artifact usually on fine data. On large low contrast data, the larger AP boxes work fine. If you're having artifact results, try going smaller on AP size (or if already really small, try larger). In general, the only detriment to using smaller AP and lots more AP is simply the processing time.

Very best,


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Re: AS3 question

Post by Ivan »

MalVeauX wrote: Thu Jul 15, 2021 1:53 pm Hi,

Lower the minimum brightness value. Yours is at 10...
Marty, many thanks for the comprehensive answer, I learned a lot, especially about the addition algorithm. I followed your advice and Alexandra's advice and AP appeared on a black background. Many thanks.

Ivan


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Re: AS3 question

Post by christian viladrich »

In case you want to make sure there is no detail in the "black background", you can use "Display option / Brightness X1 or X4" (on the top right of the image window).
This won't change the data, but helps vizualisation of faint details. Then you can adjust "Min bright"accordingly.


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Re: AS3 question

Post by Ivan »

christian viladrich wrote: Sun Jul 18, 2021 3:21 pm In case you want to make sure there is no detail in the "black background", you can use "Display option / Brightness X1 or X4" (on the top right of the image window).
This won't change the data, but helps vizualisation of faint details. Then you can adjust "Min bright"accordingly.
Thanks a lot for the great advice Christian!

Ivan


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