Zerene: salvaging drifting image series

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Bob-O-Rama
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Zerene: salvaging drifting image series

Post by Bob-O-Rama »

Hi,

I have a series I am trying to salvage where the camera or subject has slowly drifted during the series, about 40% of the frame vertically, 10% horizontally. Zerene does what it does and leaves streaks iom the edges in those areas. Which is entirely understandable and documented.

Anyways, I tried fooling it with adding a few hundred pixel border to the images in the series. It found the border to be a way better feature to register the images against. So inside out version of the problem.

So the question is, is there a border color / texture that Zerene will not feature match against for registration purposes? Is there a way to do feature matching against the interior nn% of the image? Or can transparency be used - thinking tiffs.

OTOH, this has resulted in some great abstract artwork.

Thanks!

rjlittlefield
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Post by rjlittlefield »

The short answers are no, no, no, and it's very likely a lost cause anyway.

That said, try adding just a 1-pixel border around your images, using some color like "gray" that approximates the rest of your image. That will cause the shifted images to develop gray bands in the regions that would otherwise have had edge streaks in them. Sometimes this will improve alignment in the remaining "good" areas that are covered by all frames, and maybe you'll get something you can live with.

The reason I say "it's very likely a lost cause anyway" is that Zerene Stacker's alignment process uses only 2D translate, rotate, and scale -- no warping. If your camera and/or subject has managed to shift by such a large amount, there's a really good chance that your images have perspective shifts or other kinds of warping that make these 2D transforms simply not adequate to keep subject features lined up from one frame to the next.

Those types of warping are commonly encountered with stitched panoramas, so you might consider using some panorama stitching program like PTGui or even Photoshop to warp and align the images so they match, then crop to common area and feed the resulting matched images into Zerene Stacker to do the focus stacking.

--Rik

MarkSturtevant
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Post by MarkSturtevant »

I've done some stacks where there was movement due to breezes and probably some camera movement on my part. Some I had to abandon as stacks, but a couple could be salvaged to some degree. What was key was that there were not many frames in the stack. If there were a lot of frames, I would not want to bother.
The trick was to identify a small # of frames that do align, and make a short stack with those, with retouching. The result was a few pictures that were partially stacked. Then these were imported into a photo editing program like Gimp or Photoshop,and parts of the subject in one picture was copied with the lasso tool, and pasted into a different picture. Aligned, and sometimes adjusted with a perspective shift tool (in Gimp) before it was fused into a single layer. Then cloning and healing brush tools to make it all look acceptable.
This can be a lot of work. I have learned though that if the intended picture is not 'one of a kind', then don't bother, b/c this can be a lot of work.
Mark Sturtevant
Dept. of Still Waters

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