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Comment by vanderZwan | Hacker News Reader

Image alignment allows for some fun image manipulations like these. I think one of the coolest novel applications of image alignment in recent years must be multi-frame super-resolution. For example, the Pixel phones use it to improve low-light and zoomed in photos[0].

[0] https://sites.google.com/view/handheld-super-res/

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This is called drizzle (with dithering, e.g. the raw photos are taken with offsets) in the astrophotography sphere and is very effective when the images are undersampled. Although, astronomy images have the advantage of being filled with stars that are relatively easy to align very accurately.

'When undersampled' -- time to get a more modern sensor?

3.76um pixels + 800mm focal length is about 1 arcsecond per pixel, so that will end up seeing limited much of the time.

Many undersample on purpose and get better results that way. You can workaround seeing a little with lucky imaging and patience, being very selective.

Also, drizzling was developed originally for the Hubble Deep Field, which isn't limited by seeing :).

I imagine the minuscule vibrations of a shutter make it a natural fit to the already existing image stacking pipeline, correct?

I'm not sure what you mean. Mechanical shutters have no upsides I'm aware of :). Astro cameras use electronic shutters. EDIT: The dithering, or offsetting, is done by moving the telescope slightly between exposures. During exposures you want it to track the object you're photographing as accurately as possible. I imagine vibrations are a detriment even in the Pixel phone processing. It would be better if the phone could move instantly in slightly different directions and take steady raw photos in each.

Ah, I was thinking of amateur astrophotography - although these days you can just set the mechanical shutter in many consumer DSLRs to stay open too I think.

I think maybe you were considering the vibrations a source of noise for compressed sensing? For CS to work well you generally want to know the convolved noise. So a super accurate accelerometer might be able to measure random vibrations and do even better when they are present than absent. Not sure if phone accelerometers are that good.

Yes, I believe Google's team publicly says it helps add just enough random translation.

Do camera phones have mechanical shutters? I'm almost certain they don't.

On camera phones the random movements come from the users own instability when taking pictures.

I wonder if you could use alignment of multiple samples for better vectorizing of letters of old books. You could create very nice vector only pdfs.

Yes! For a two-fer, take a pair of cell phone photos of the open book, compute a 3D model, and flatten it as if the book had been sliced and scanned. Now match up all the letter E's in the entire book for image enhancement.

Vectorization is nontrivial. Most academic journal articles are now poorly scanned, and it would be nice to simply improve the scans.

Cool! I'm planning on using image alignment for enhancing the spatial resolution of hyperspectral (HS) images, through the fusion of RGB and HS images.

You get something similar to a panchromatic image?

You can use an high-resolution panchromatic image to increase the spatial resolution of an RGB image. Here the objective is to do the apply the same idea but using an RGB and HS image, increasing the spatial resolution of the latter.

Does this mean that objects that are on a trajectory out of the view have less resolution?

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