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Superresolution - Stacking increases resolution 400%

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#1 CharlesC

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Posted 19 February 2019 - 04:21 PM

I've always known stacking increases dynamic range dramatically but didn't realize it increases resolution up to 400%.  

 

Photographers increase resolution with the "Super Resolution" technique which is stacking.

https://petapixel.co...with-photoshop/

 

Stumbled across "Super Resolution" watching video on Opportunity Rover here.

https://youtu.be/oZBHHXDUSI8?t=261

 

So stacking effectively turns a 1 megapixel camera into a 4 mega pixel camera?


Edited by CharlesC, 19 February 2019 - 04:46 PM.


#2 DuncanM

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Posted 19 February 2019 - 04:31 PM

The technique described is essentially stacking using the "drizzle" algorithm:

 

https://en.wikipedia...age_processing)

 

BTW, some Pentax DSLRs also use a similar, in camera, technique.


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#3 Ron359

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Posted 19 February 2019 - 04:47 PM

The article seems to be about sharpening not stacking but written with so much marketing hype I can't tell for sure...  

 

But stacking or sharpening doesn't 'make new pixels' by 4x.  Resampling can only interpolate whats already there.   Sorting & stacking many hundreds of frames throws out the worst then 'reinforces' and brings out and aligns whats already there, but scrambled by seeing.   You should follow the solar system imaging group cause stacking and wavelet sharpening is the basis for all modern astro 'lucky imaging' used to get high resolution sub arc sec. details in images of planets, Sun, moon etc.,  Images are far better than was done by the largest telescopes with a few film shots 25 yrs ago.  



#4 CharlesC

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Posted 19 February 2019 - 05:01 PM

The article seems to be about sharpening not stacking but written with so much marketing hype I can't tell for sure...  

 

But stacking or sharpening doesn't 'make new pixels' by 4x.  Resampling can only interpolate whats already there.   Sorting & stacking many hundreds of frames throws out the worst then 'reinforces' and brings out and aligns whats already there, but scrambled by seeing.   You should follow the solar system imaging group cause stacking and wavelet sharpening is the basis for all modern astro 'lucky imaging' used to get high resolution sub arc sec. details in images of planets, Sun, moon etc.,  Images are far better than was done by the largest telescopes with a few film shots 25 yrs ago.  

 

If you scroll down it has this particular paragraph:

 

 

Up to 4x Spatial Resolution Increase

 

While there is a very apparent and measurable resolution increase, it’s limited. Even if we used hundreds of stacked frames (not recommended), we probably would not be able to increase the actual spatial resolution of the image past about four times the original or 200% on each edge, length and width.

 

This limit is due to a number of reasons: the imprecise and random nature of our “sensor movement” (hand shake), inaccuracies in our layer alignment (pushing the limits of Photoshop’s auto-align function) and the fact that we’re simply averaging the pixel level details rather than writing a sub-pixel level demosaicing algorithm specifically geared toward multi-image superresolution.

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#5 t_image

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Posted 19 February 2019 - 10:34 PM

Just to clarify for any readers out there without need to interpolate numerous articles:

 

the resolution benefit of processing multiple images comes from two concepts:

 

#1 elimination of atmospheric distortion which necessarily increases clarity (bright subjects, fast exposures (usually video frames))

 

#2 a different way to increase resolution---taking advantage of sub-pixel level movement between images.

This comes from 2 parts:

A. in acquisition, a method of "dithering" needs to happen (either intentionally or accidentally). "dithering" happens when many images are acquired of the same subject,

but there are slight variations in the positioning of the sensor in reference to the subject,

so that different sensor pixels capture slightly different parts of the image each time.

B. in processing, a method of "drizzling" is utilized-where stacking of the different images (in sub-pixel precision) with sub-pixel variances gives rise to reliable sub-pixel resolution--or super-resolution.

 

Note a completely static subject that's light consistently falls on the same sensor pixels throughout acquisitions of many image subs, means no "dithering" has happened, and without such spatial variations between subs,

no super-resolution results can be had.....


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#6 CharlesC

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Posted 20 February 2019 - 12:24 PM

At bottom of original link it lists process to increase resolution with stacking.

 

 

1. Import all photos as stack of layers
2. Resize image to 4x resolution (200% width/height)
3. Auto-align layers
4. Average layers

 

If makes sense that you can only increase resolution with stacking if initial images are resized 4x.  Then sub-pixel averaging can occur by stacking increasing resolution.  Sharpcap should have an option to do this, but don't think it does. 



#7 diceless

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Posted 20 February 2019 - 02:26 PM

This is something Deep Space Stacker already supports but I'm not sure if it can be turned on in AstroToaster/DSS Live.  I haven't seen support in other EAA programs yet.


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#8 CharlesC

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Posted 20 February 2019 - 06:57 PM

This is something Deep Space Stacker already supports but I'm not sure if it can be turned on in AstroToaster/DSS Live.  I haven't seen support in other EAA programs yet.

I looked at DSS manual on drizzle here.  Looks like they support 2x and 3x  drizzle AKA "super resolution". 

2x would required 400% more processing time and 3x would require 900% more processing time.

Kind of doubt realtime programs like DSS Live or Sharpcap could keep up in realtime.

Maybe AstroToaster could do it since it operates on folders of pics not real real-time.



#9 Howie1

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Posted 20 February 2019 - 07:10 PM

Every setting in DSS is 'read' by Astrotoaster ... you simply have to make the change in DSS then in its left hand menu down under Save Settings you save them. From then on Astrotoaster simply hands the frames to DSS in the background and DSS does the stacking and processing based on the settings within DSS which you set and saved. When its done processing every frame Astrotoaster simply shows you the resulting image from the DSS processing.

 

You make the change in DSS then in Astrotoaster click the button which says to refresh from DSS settings. 

 

IE If the setting is in DSS ... and you turn it on and save that change within DSS ... then it is how the frames from toaster will be processed.

 

BTW While my name happens to be Howie I am not the Howie Levine who wrote AT .... I'm just a very happy AT user who has used AT for many years.


Edited by Howie1, 20 February 2019 - 07:11 PM.

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