Stacking for resolution

[soc123]

Hi all

I have seen the various videos on stacking but am trying to use it for simple resolution increase - I am starting with a 16MB raw file and ideally want to print from a jpeg at 48" wide. This requires a raw file of about 100MB. I have seen stacking used in this way in Photoshop by resampling a large stack 200%, but this doesn't get me to that size. Would it be possible in AP and how many images would it require?

[Callum]

Hi Soc123,

I'm not sure if I have understood your question correctly. Why are you using Stacking to increase the resolution of an image rather than resizing it or exporting it at the resolution you would like?

Thanks
C

[firstdefence]

You might be able to work this into Affinity Photo ...

Quote

There are numerous tutorials providing instructions for creating a super resolution image in Photoshop – this one by Ian Norman on PetaPixel is among our favorites. Distilled down to its simplest terms, there are four easy steps:

1. Bring all images into Photoshop as a stack of layers
2. Resize the image to 200% width and 200% height using 'Nearest Neighbor'
3. Auto align all the layers
4. Average the layers by setting each layer's opacity to 1/layer number (the 1st layer will be 1/1 so 100% opacity, the 2nd layer will be 1/2 so 50% opacity, and the 4th layer will be 1/4 or 25% opacity, and so on).
5. Sharpen the image using a Radius setting of 2, and a suitable Amount setting (we used 200% for the 4 image stack and 300% for the 20 image stack – the more images you stack the more amenable the composite will be to aggressive sharpening)

Alternatively, for the fourth step you can convert all layers to a 'Smart Object' and change the stacking mode to 'Median'. This can help deal with ghosting from movement in your final image, but can also take longer to process.

Finally, you can resize the final output by 50% width and height (we prefer Bicubic resampling for this step) to get the shot back to its original resolution, but with far more detail and cleaner output. Or, you can opt to save the high-resolution file if you print big, but just keep in mind that for a 36MP camera, that's a 144MP file. You can always re-upscale a super resolution file you've shrunk, and if you use the 'Preserve Details 2.0' resampling method in Photoshop to do so, the results are often impressive and sometimes hard to distinguish from the higher resolution super resolution file.

https://www.dpreview.com/articles/0727694641/here-s-how-to-pixel-shift-with-any-camera

[walt.farrell]

Super resolution has been discussed in these forums several times: https://forum.affinity.serif.com/index.php?/search/&q="Super resolution"&quick=1&updated_after=any&sortby=relevancy

[soc123]

3 hours ago, Callum said:

Hi Soc123,

I'm not sure if I have understood your question correctly. Why are you using Stacking to increase the resolution of an image rather than resizing it or exporting it at the resolution you would like?

Thanks
C

Hi @Callum

Because I want to print at large size with minimal loss of quality. I can get to 48" at 150dpi using stacking and resampling, but I don't see any difference at native resolution between the stack group and a pixel layer (except that the mean operator sharpens the image a little). The images are not shot handheld. Perhaps that is the problem?

Edited September 23, 2022 by soc123

[soc123]

6 hours ago, firstdefence said:

You might be able to work this into Affinity Photo ...

https://www.dpreview.com/articles/0727694641/here-s-how-to-pixel-shift-with-any-camera

Thanks but none of this seems to work in Affinity. I have tried handheld with 30 images but still don't see any difference. If you halve the opacity as you go down the stack you quickly get to less than 1%, so I don't see how they have used a 20 image stack.

[NotMyFault]

The name of the method is misleading similar to “cruise control” or “auto pilot” in automobiles.

It does not increase resolution. (Except when done in-camera by exactly 1/2 pixel shifts).

What the method does is reduce noise, and allowing much stronger sharpening after regular upscaling (which always blurs)  to get the impression of higher contrast and more details, without negative side effects of strong sharpening. 
 

Sharpening does not increase resolution, but it gives the visual illusion of a higher resolution image.

I have experimented quite a bit with stacking for moon shots. As general result: you often get better image quality from one single shot with careful post-processing compared to stacking multiple shots of varying quality. You need to inspect every single source image and sort out those with sup-par quality, otherwise you stacking results fall behind. 
 

for moon shots, the thermal noise of atmosphere introduces lots of “wandering around” highlights which lead to virtual larger shapes, looking nicely after stacking, but not representing any actual physical structures. It is similar to AI upscaling: you get results that are nice looking, but artificial in the sense on non real, but made up.

[soc123]

3 hours ago, NotMyFault said:

The name of the method is misleading similar to “cruise control” or “auto pilot” in automobiles.

It does not increase resolution. (Except when done in-camera by exactly 1/2 pixel shifts).

What the method does is reduce noise, and allowing much stronger sharpening after regular upscaling (which always blurs)  to get the impression of higher contrast and more details, without negative side effects of strong sharpening. 
 

Sharpening does not increase resolution, but it gives the visual illusion of a higher resolution image.

I have experimented quite a bit with stacking for moon shots. As general result: you often get better image quality from one single shot with careful post-processing compared to stacking multiple shots of varying quality. You need to inspect every single source image and sort out those with sup-par quality, otherwise you stacking results fall behind. 
 

for moon shots, the thermal noise of atmosphere introduces lots of “wandering around” highlights which lead to virtual larger shapes, looking nicely after stacking, but not representing any actual physical structures. It is similar to AI upscaling: you get results that are nice looking, but artificial in the sense on non real, but made up.

I see. Thank you for that. I can see good results with four images now I have shot handheld.