Yesterday I slipped with my bicycle and scraped my knee pretty badly. To make the best out of it, I decided to take a picture of it every 6 hours and make it into a time-lapse kind of slideshow to get a closer look on the healing process. I'll probably do it for around a week, which would make about 30 pictures.

I set up a tripod and chair to keep the perspective the same, but of course I can't position my knee perfectly every single time, so I'll have to slightly crop the pictures afterwards so they all line up with each other perfectly.

How could I do that? What software/workflow is a quick way to exactly crop my pictures? I assume using something like a semi-transparent layer in Photoshop to put one image over each of the others could work, but it would be pretty annoying to do 30 times in a row. Anyone knows a more smart/economic solution?

  • Why not make a frame to hold your knee in one position? E.G., split a heavy-weight cardboard tube lengthwise, notch and bend it to fit comfortably behind the knee, holding leg and thigh, and leave it in one place? BTW, great project idea! Post the video on Vimeo or Youtube, and let us know. – DrMoishe Pippik Dec 18 '20 at 3:18
  • @DrMoishePippik Good idea, but probably not easy to set up in a way so you don't require ANY correction afterwards. What I've done is put up the chair and tripod and stick a small piece of tape on my camera screen which I line up with a significant spot on my knee. That said, I'd like a digital solution anyway because it will likely be applicable to many different situations as well. – MaxD Dec 18 '20 at 3:42

Panorama applications can usually auto-align a stack of photos since this is a special case of the adjustments needs for correct stitching.

For instance how you can use Hugin for this is shown here.

To get to the interface used in the guide, go to View -> Panorama editor. Also make sure Interface in the menu bar is set to Expert, or the Remapped Images section used in the last step will not be visible.

  • Thanks! Can you add a few lines on how to run this? Seems like I need PanoTools to run Hugin, but the PanoTools I found is just a bunch of java files and I have no idea what to do with them. – MaxD Dec 18 '20 at 23:26
  • No, Hugin is a regular app. You can get it here. – xenoid Dec 18 '20 at 23:29
  • Added two caveats that took me way too much time to find out. – MaxD Dec 19 '20 at 18:43

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