I've got a few hundred photos of the November 2012 eclipse, and I'd like to compose them into a time series. To do that, I'd like to crop all of them to the same size, a square with a little space between the Sun and the edge of the image. Using ImageMagick I was able to create the following image with convert original.jpg -fuzz 5% -trim +repage cropped.jpg:

cropped solar eclipse photo

Alright for a first step, but how can I make sure that

  1. the borders on all sides are approximately the same size and
  2. the image center corresponds to the center of the Sun (that is, the extrapolation of the outer arc), rather than the center of the bright area?

Manual methods are not feasible, because of the amount of images.

Here are the first three images: 1 2 3

  • 6
    How about aligning these images with Photoshop/Gimp/Hugin/align_image_stack and then cropping? – Unapiedra Dec 29 '12 at 15:44
  • 1
    @Unapiedra Seems like align_image_stack will work with a few hours of computation; I'll get back to this when it's done. – l0b0 Dec 29 '12 at 16:28
  • 1
    Out of interest, how many images have you got? Is your machine multi-threaded (most are), if align_image_stack is single-threaded, split up the images and align them in groups, and then align the groups later on. But I guess you already thought of that. – Unapiedra Dec 29 '12 at 17:15
  • @Unapiedra A few hundred. – l0b0 Jan 11 '13 at 14:33
  • 1
    If you are not going to do this again, then manual methods may very well be feasible. If you put them all in layers, and put some guides on I would estimate 15 seconds per image to align- that's 240 images per hour. Decide if an automated solution will take less than one or two hours to set up. "Less than 3 times, do it by hand, more, do it by script" – Phil Jan 17 '13 at 19:05

Assuming the camera didn't move throughout the sequence, I'd do the first and the last images by hand, making certain to trim both to the same size frame. Then interpolate the position of the frame for each intermediate image based on the image's timestamp. It shouldn't be hard to write a script that does that for you. Even a spreadsheet would work for calculating the frame position for each image, and you could probably massage that into a list of crop commands, one per image.

| improve this answer | |
  • The camera did move during the shoot (to keep the Sun within frame), so this is not an option. – l0b0 Jan 17 '13 at 20:59
  • @l0b0 You can do the same thing then, but you just need to work in smaller batches. Do the first and last image in each group of images where the camera was stationary, and repeat as necessary. If it moved a lot, that's obviously a problem. – Caleb Jan 17 '13 at 21:03

I suggest you use a movie compositing software like Adobe After Effects, Apple Shake or Autodesk Combustion. Those programs have been around for years and should be available for cheap on ebay.

They were made for image series and deliver professional results.

You can use the tracker function to position the sun within the frame.

| improve this answer | |

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.