How to remove unwanted intrusions from scenic photos


So there you are in front of the Taj Mahal or some other tourist site and you want to take a photograph of it. Unfortunately other people also like these sites and wander across the frame of the photo as you are setting up. Some will notice you and be considerate enough to wait for you to finish or walk behind you but most will be oblivious that they are ruining your shot.

OmerRAnderson suggests a simple way to use technology to eliminate all transient intrusions into your photographs. It seems ingenious to me and I pass it along even though I am not a photographer and have no idea if this actually works or not. Some commenters raise problems and suggest ways to improve it.

scenic photos

Of course, this does not solve the problem of people who hang around for a long time. With such people, you may have to revert to the old-fashioned way and politely ask them to move.

Comments

  1. says

    Yes, it definitely works.
    The first I saw of this technique (Image Stacks) was in the SIGGRAPH 2004 paper linked to at this page:
    http://grail.cs.washington.edu/projects/photomontage/
    It’s an interesting read if you are into graphics algorithms.
    Some of the techniques described in that paper made their way into Microsoft Digital Image Suite in 2004 and are discussed in a blog article by Scott Hanselman here:
    http://www.hanselman.com/blog/NewDigitalPhotoTechniquesFromMicrosoftResearchIntegratedIntoMicrosoftDigitalImageSuite9.aspx

  2. Johnny Vector says

    They forgot step 0: Pay Adobe $120/year for Photoshop.

    This also involves dealing with Adobe’s licensing scheme, which may be sensible now but it pissed me off so badly a few years ago that I gave up even trying to use their products.

  3. says

    Nah, it’s not sensible, and it gets worse and worse every year. I finally just dropped photoshop altogether, and am using GIMP instead.

  4. komarov says

    Paint.net seems to be able to something like that as well (not that I’ve tried it; no historical sites nearby to photograph). And unlike adobe it only asks nicely if you’d like to donate when it updates.

    The technique is very clever indeed. I wonder what it would look like without the tripod. Not knowing what exactly the median filter does (or how), the result could be very dull (erasing everything) or it might produce some interesting patterns depending on how shaky your hands are.

  5. Johnny Vector says

    Well assuming the camera is well locked down (no vibrations from a dime store tripod), the lighting doesn’t change from image to image, and for each pixel the background is visible in at least half of the images, you literally just have to stack up the images and take the median value of the stack for each pixel.

    If more than half of the images have a person in them, you’d have to make a histogram for each pixel and take the most common value.

    If the camera is not locked down, you suddenly have to get much more sophisticated, and register the images before doing the median filter. If there aren’t too many tourists in the frames you could probably do a simple correlation to register them. If the camera has significant geometric distortion you’d have to take that out at the same time, which is probably easy for modern image processing algorithms, but not for the likes of me. (Of course the last time I did anything to do with image processing it was on a PDP-11 with 32K of data memory, so that’s not saying much.)

  6. eidolon says

    It’s a bad day when ya don’t learn something. Here I’ve happily using CS 6 and Lightroom without knowing about the change in licensing.

    There are still good options – Photoshop Elements 14 – the latest iteration – and Lightroom 6. Both can be purchased for far less than any of the old Creative Suites and for 99.9% of photographers, will do about anything you need to do. They have the old perpetual licenses and no subscription. They will not do this one particular task, but I’ve always been able to handle it in post.

    Now – if you’re just pissed off by the new licensing, be ready to remain pissed off since this is a coming thing. You are “owning” less and less of your software, music, videos and e-books.

  7. says

    This is why “real” photographers still carry tripods.

    Re: photoshop – I still use PS 7.0. It runs like lightning on a modern machine. I paid $100 for it in 199? – good deal. Newer versions of PS don’t add much to the core requirements for photography, though they have done a lot for graphic designers and commercial photographers’ production line. The best thing is you can get PS7 for free now. It has layers. Almost all the new stuff in newer versions is based on layers.

  8. komarov says

    As happens so often I read ‘median’ and thought ‘mean’. Thank you, brain, and thank you, Johnny, for the explanation. I’m currently learning about various processing techniques so that was both interesting and helpful.

  9. Steven Janowiecki says

    Astronomers have been doing this sort of thing with images ever since CCDs were first used on telescopes (~1980s) and spy satellites used them a decade before that (e.g. https://en.wikipedia.org/wiki/KH-11_Kennan ) – it’s a powerful technique indeed, and useful in vacation photos as well as galaxy images.

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