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GreatGigInTheSky
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Reged: 02/06/11

Loc: Santa Clara, California
Re: Speckle Reconstruction new [Re: RedLionNJ]
      #5685222 - 02/17/13 01:24 PM

Hi Emil,
Interesting about the drizzling. It's not anything about AS!2 that causes me difficulties at 3x drizzle -- it's just that either R6 and/or my own ineptitude, in spite of multiple attempts at it, have made it impossible for me to come up with a workable sharpening routine for 3x images. For 1.5x, I've got it dialed in -- I always use the same saved wavelets, then just make minor tweaks to those settings for the specific data. And in line with what you've written above, these wavelet settings are completely different from what I would use at native image scale, so I wouldn't expect either of these schemes to work at 3x, but rather worked from scratch to get something that produced a reasonable result at 3x, but to no avail -- I've always been far more happy with my 1.5x results that anything else I've been able to do.

I'm curious, though, about your choice of going all the way to 3x for drizzling. Why did you not pick 2x?


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MvZ
Carpal Tunnel
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Reged: 04/03/07

Loc: The Netherlands
Re: Speckle Reconstruction new [Re: GreatGigInTheSky]
      #5685335 - 02/17/13 02:25 PM

No particular reason I guess, other than that it is nicely symetrical. I prefer the 3x and 5x options, they are easy to implement.

With drizzling you also have to define how large the original pixel gets when it 'rains' onto the pixels of the finer grid. With a grid only twice as large, that process cannot be done as accurately. On the other hand, a drizzling size of 5x requires A LOT of memory, so 3x seemed to be a good solution that works in most of the cases.


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DesertRat
Postmaster
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Reged: 06/18/06

Loc: Valley of the Sun
Re: Speckle Reconstruction new [Re: GreatGigInTheSky]
      #5685476 - 02/17/13 04:24 PM

Jeff,

When the image is resampled as much as the 3X drizzle provides, I recommend you look at setting the 'Initial Layer' on the R6 wavelet page to 2. Then use similar (though a little different) slider settings to sharpen.

I have not used 3X drizzle much at all but I often resample raw tiffs up anywhere from 2.5X to 4X using Bicubic B-Spline for example in PixInsight. The Initial Layer 2 setting in R6 works for me in that case. You may find for some images that you will have to lower the sharpen box from the default 0.100 down to as low as anywhere from 0.040 to 0.080.

Glenn

Edited by DesertRat (02/17/13 04:46 PM)


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DesertRat
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Reged: 06/18/06

Loc: Valley of the Sun
Re: Speckle Reconstruction [Re: MvZ]
      #5685504 - 02/17/13 04:43 PM

Emil,

After reviewing what you have demonstrated I have to say I'm amazed at your solar speckle results. That comes pretty close to magic. I know it is'nt but the first view of your results were startling.

Concerning super-resolution it seems we have been doing this for some time without realizing it in the case of somewhat undersampled setups. What comprises an undersampled setting has been a subject of debate however.

It also occurs to me that one could argue the following: In seeing conditions where small details are visible but they are moving a fair amount between frames that a case could be made that it might be better to lower the efl and the exposure time. After all these years of lucky imaging and endless debates about nyquist sampling and optimum exposure settings I find myself questioning some of these points once again!

Thanks for waking up some of our collective brain cells!

Glenn


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