There are however other plugins you might find useful in this. There is ImageJ which has an astrophotography plugin that would be very similar to your use case except that in astrophotography the "smudge" is assumed symmetric and spatially invariant (same across the image).which yours might not be. The deconvolution bit is a bit more involved. Gimp to stack the (aligned) images (in layers) and obtain the average image that would reveal the smudge. Octave or skimage ) but for a quick test you could use: These operations can be applied with low level image processing tools (e.g. I don't know if tools already exist that could do this, but any guidance as to algorithms/approaches would be much appreciated If you had to do measurements on the affected pixels, or look for patterns, this filtering operation could distort your results. This can be used to diminish the shadow (at least) or deconvolve the affected regions to diminish the "focus shadow" too.īut, whether this is successful also depends on the use of the images. If N is high enough (at least 20 but it depends on image content too) then you will start to see the smudge shape over a (mostly) average background. If not, then you will have to align them. This is assuming that the N images have the smudge at exactly the same position. Short of obtaining an "empty" scan, you could try to obtain the average frame over N ( grayscale) images. This is even worse if the smudge has been changing slightly with every image acquisition. The main problem here is that you will not be able to recover an exact "image" of the smudge, so that you can then invert it. This second bit could be corrected with a "filter", but it's easier said than done. It is exactly like having an extra lens on top of the existing focusing mechanism. Therefore, even if you correct the shadow, the "focus shadow" will still be there. finger markings, droplets, gel, etc) then it not only has diminished the light that went through it, it also has changed its path. If the smudge is caused by a deposit (e.g. If you had a "mask" of how much light passes through each point of the smudge, then you could get rid of it by adjusting the image pixel values (i.e. Light is absorbed and therefore the smudge leaves behind it a shadow. The smudge refracts and scatters some lightĭealing with 1 is easier than dealing with 2.There are two things that are happening here: The results depend very much to what you are working with and for what purpose. It is difficult to reply Yes or No to this question. Would it be possible to extract the "smudge" (i.e., the equivalent of an image filter applied to the physical photo that results in the scanned image), and then apply the inverse of this filter to all my images (with appropriate rotation and offset)?
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