Re:Accurate Image Alignment and Registration Using OpenCV
by gliptic on Wednesday March 09, 2022 @08:33AM
(#30614210)
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.
Re:Accurate Image Alignment and Registration Using OpenCV
by nullc on Wednesday March 09, 2022 @09:30AM
(#30614732)
'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.
Re:Accurate Image Alignment and Registration Using OpenCV
by gliptic on Wednesday March 09, 2022 @09:44AM
(#30614908)
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 :).
Re:Accurate Image Alignment and Registration Using OpenCV
by vanderZwan on Wednesday March 09, 2022 @08:44AM
(#30614306)
I imagine the minuscule vibrations of a shutter make it a natural fit to the already existing image stacking pipeline, correct?
Re:Accurate Image Alignment and Registration Using OpenCV
by gliptic on Wednesday March 09, 2022 @08:51AM
(#30614352)
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.
Re:Accurate Image Alignment and Registration Using OpenCV
by vanderZwan on Wednesday March 09, 2022 @09:01AM
(#30614452)
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.
Re:Accurate Image Alignment and Registration Using OpenCV
by galangalalgol on Wednesday March 09, 2022 @09:24AM
(#30614680)
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.
Re:Accurate Image Alignment and Registration Using OpenCV
by xhkkffbf on Wednesday March 09, 2022 @11:11AM
(#30616084)
Yes, I believe Google's team publicly says it helps add just enough random translation.
Re:Accurate Image Alignment and Registration Using OpenCV
by IAmEveryone on Wednesday March 09, 2022 @11:40AM
(#30616547)
Do camera phones have mechanical shutters? I'm almost certain they don't.
Re:Accurate Image Alignment and Registration Using OpenCV
by dr_zoidberg on Wednesday March 09, 2022 @08:44PM
(#30622322)
On camera phones the random movements come from the users own instability when taking pictures.
Re:Accurate Image Alignment and Registration Using OpenCV
by legulere on Wednesday March 09, 2022 @09:58AM
(#30615071)
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.
Re:Accurate Image Alignment and Registration Using OpenCV
by Syzygies on Wednesday March 09, 2022 @12:18PM
(#30617185)
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.
Re:Accurate Image Alignment and Registration Using OpenCV
by magamig on Wednesday March 09, 2022 @08:27AM
(#30614160)
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.
Re:Accurate Image Alignment and Registration Using OpenCV
by is_true on Wednesday March 09, 2022 @09:44AM
(#30614898)
You get something similar to a panchromatic image?
Re:Accurate Image Alignment and Registration Using OpenCV
by magamig on Wednesday March 09, 2022 @09:56AM
(#30615054)
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.
[0] https://sites.google.com/view/handheld-super-res/