Google finds that this subject came up long ago (see third case study bullet here) https://darktable-devel.narkive.com/7Bual2Yk/deconvolution-and-python-framework
This is what they call "deconvolution". It is well known. First you need a "point spread function" (PSF) for your out of focus image. To get this you take a photo of a geometric "point" using the exact same lens setting, relative motion and focus error. Then you convolve the PSF with the image. "everyone who implements this uses FFTs to do the convolution. This works really well on deep sky images because almost every image has a record of the PSF because it records images of stars. In a nut shell the algorithm is this: In a blurred image (all images are blurred) each point on the physical subject is mapped to a "blob" (PSF) on the CCD or film. So the image is the sun of an infinite number of superimposed blobs. If you know the exact shape of the blob you could reconstruct the subject but with no blur. We must first guess or measure the shape of the blob and then do a 2D convolution of the blob and the image. But we do it interactively a little at a time until we don't see an improvement. They call this Lucy-Richardson Deconvolution. Google either Lucy-Richardson or Richardson-Lucy. And find many examples in C and Python. For large images you really want to do the convolutions using the FFT. Bu the PSF is not known in most images. One common idea is to create the PSF algorithmically based on parameters or maybe even use a generic PSF where the user uses sliders to adjust the parameters. But there is nothing better then to have stars on the images. This technique was made famous by Hubble but was well known years before. The first time I heard about it was for NASA's Pioneer Venus mission. It was used to process the synthetic aperture radar data. On Fri, Nov 12, 2021 at 12:25 AM Dr. A. Krebs <i...@axel-krebs.de> wrote: > Dear all: > > I just came across a potentially new sharpening procedure on "Profifoto" > magazine: > < > https://www.profifoto.de/neuheiten/software/2021/11/02/schaerfung-mit-deep-sky-methoden/> > > . > > (in German language) > > According, it is transferred into a PS plugin. > > Maybe it is possible to adapt it for darktable? > > > Axel > > ____________________________________________________________________________ > darktable user mailing list > to unsubscribe send a mail to > darktable-user+unsubscr...@lists.darktable.org > > -- Chris Albertson Redondo Beach, California ____________________________________________________________________________ darktable user mailing list to unsubscribe send a mail to darktable-user+unsubscr...@lists.darktable.org
