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I often go to presentations and take photos of slides. Sometimes I sit too far, and photos come out blurred or noisy.

It is known that if to take N photographs of the same object from exactly the same point in the same lighting conditions, and to average them pixel-wise, this would denoise them and would improve the apperant quality.

However, in case of photographs taken with a cellphone by hand they (1) will be slightly offset or rotated because of hand movements, (2) might have some areas obscured in some of them.

My question is: "Is there a linux software that is able to take, say, 2-10 photos of the same slide, find the most likely offsets/rotations, compansate for them and for obscured areas, and improve image quality?"

mattdm
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Jennifer M.
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  • Although I think this is on-topic for Photography SE, I'm wondering if you might have better luck at Software Recommendations SE? – Michael C Apr 28 '19 at 03:19
  • Will ask there if nobody answers in a few days. Thanks for your suggestion! – Jennifer M. Apr 28 '19 at 03:33
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    Have you tried align_image_stack? It would be easier to sit closer, get a tabletop tripod, or ask the presenter for a copy of the slides. – xiota Apr 28 '19 at 08:36
  • @xiota I will try align_image_stack, I didn't know about it. Sitting closer isn't always possible. Getting a tripod isn't an option, often there are no tables, only seats. Asking for copies is also impossible, and unethical. Presenters don't give away slides. They consider this their work and are afraid that someone would just use their slides to advance their career. I am just trying to see how much is possible only using a camera + software. – Jennifer M. Apr 28 '19 at 16:22
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    "Asking for copies is also impossible, and unethical." – If the presenter is unwilling to give you a copy of the slides, then isn't photographing the slides also "unethical"? I don't know what field you're in, but for most presentations/lectures I attend, a print out of the slides is provided to attendees to take notes on. – xiota Apr 28 '19 at 20:31
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    Possible duplicate of What open source software for auto-alignment of photographs? – xiota Apr 29 '19 at 07:16
  • @MichaelC The accepted answer at the duplicate question is Linux compatible. – xiota Apr 29 '19 at 23:41
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    @MichaelC FWIW, yes, Hugin runs on Linux. – mattdm Apr 30 '19 at 21:04

1 Answers1

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What you are talking about is called photo stacking, a technique that is frequently used in astro photography.

The procedure consists of 2 steps:
1) Aligning the photos to eliminate small movements of the camera
2) Stack the aligned photos in to one

There are several programs that can do this, they are made for astro photography though, I don't know how well they can handle partly blocked images. A free program that is highly recommended is DeepSkyTracker, it does not seem to be available for Linux though.

Gimp is very well suited for stacking images, it does not have tools included by default to align them. For aligning the images a plug-in or an external program needs to be used.

Orbit
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