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Any leads for fixing variably stretched images from a scanner?


plantguy123

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So I have an obscure problem. I take timelapses using computer scanners. Right now I am watching a fungus colonize legumes (tempeh). The motor and/or belt on one of my scanners is acting up. In some photos it will go a bit slower on some portions of the scanner platen, which has the effect of making those portions mildly stretched. When these images are rendered into a video it kind of creates a shimmering effect.

I had this problem before, but it turned out that the problematic images were stretched uniformly, so I was able to create a PS action where I stretched them back using Free Transform and it fixed the problem. The problem with this timelapse is that the stretching happens very subtly and non-uniformly so you would have to go image by image and determine which portions of each image are stretched, and manipulate them back to how they should be. That would be very hard to do manually.

Maybe this would be in the domain of a different program, but would there be any way for Photoshop (or another program) to detect which parts of the images in the sequence are stretched and stretch them back automatically?

Here's a video showing the problem:


Here's an image sequence if you'd like to experiment:


Any leads would be much appreciated, thanks!
 

thebestcpu

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Hi plantguy

The easiest and most sure way of fixing the problem is getting a scanner without the problem. Its the root cause problem and there are many used scanners out there for low prices if new scanner is prohibitive.

That would be plan A. Plan B is as follows

Import files as Layers
Select all Layers
Edit > Auto Align Layers
Open up the Timeline panel and create an animation
Use from the upper right panels options "Make Frames from Layers"
Set the time desired for each frame
Convert timeline to video
Render Video as desired

I have attached an ~8 second video of the frames you provided. It does not jump around as did your video yet it is not perfect.

That was my attempt and hope that helps
John Wheeler

Here is the dropbox video link:
https://www.dropbox.com/s/1hfx5mewhxukwy6/stabilize high quality.mp4?dl=0
 

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