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by evan-pak

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I have taken a series of noisy photos without a tripod.

I want one less noisy version, so I need average them down to one photo.

But details of the individual images do not exactly match, so that naive attempt will lead to a blurred/ghosted image, so I need to move/rotate[/scale/whatever] all images to match the first and then average them?

What is this technique called?

  1. Adjusting
  2. Stabilisation
  3. Synchronising
  4. Converging
  5. Deshaking
  6. some other term?


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up vote 9 down vote accepted

The answer you are looking for is Image Aligning.

When you merge images for HDR on Photoshop, there is an optional 'Automatically Align Images'. The same option exist in several cameras with built-in HDR capabilities.

It is also sometimes called Image Registration but that term is overloaded as it has other meanings, for example relative to copyright.

Stacking, HDR Merging, Exposure Blending are what you do with images that are aligned already.

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The essential concept is called, simply enough, stacking and averaging. The technique is often used in astrophotography where the photographer takes a long series of short exposures which are then combined to form the final, and somewhat smaller, image. The reason they do this is to handle the rotation of the earth without an equatorial mount and to reduce noise. You will also find it used in macro photography to increase the depth of field of the image, each layer providing a slightly different plane of focus.

Why do I tell you this? Well, the software they use can be used by you to achieve a similar purpose. If you Google "image stacking software to reduce noise" you will find quite a few hits. Some will give you guidance for doing it in photo editing software, some will be dedicated software, etc. The dedicated options will usually provide some assistance in lining up the images which, I think, is the biggest problem you face.

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"When you move/rotate photos to make them match it is called photo stacking" - have I understood well? – Vi0 Mar 13 '11 at 0:16
The process of aligning, combining, and adjusting is often simply called "stacking." They're usually all done as part of the same process. – John Cavan Mar 13 '11 at 2:01

I think the word you are looking for is "aligned".

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As @John Cavan, it's usually just called stacking. I've probably mentioned it before, but the software I'd recommend for the job is CombineZP. It's free, and at least for me has been completely reliable and trouble-free (well, some old versions had a few minor problems, but that was years ago, and even then they were pretty minor).

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You might want to have a look at Panorama Tools and Enblend.

However I have to disclaim any experience with those, I just know those tools exist.

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The hugin command line tool is align_image_stack ( – labnut Mar 13 '11 at 17:31

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