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Rotoscope/Roto Brush Tool alternatives? (for footage without green screen)

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Scott JohnsonRotoscope/Roto Brush Tool alternatives? (for footage without green screen)
by on Apr 14, 2014 at 10:08:03 am
Last Edited By Scott Johnson on Apr 14, 2014 at 8:08:42 pm

The above image is a frame of a video I am trying to extract the soldiers from. I don't want to rotoscope and I don't want to use the roto brush tool (if all else fails, I will do this, but I am trying not to do this for various reasons).

If you open Audacity ( they have an option called "Noise Removal". With this effect, you select a "sample" of audio you consider to be "noise" and click "Get Sample". Once the sample is gathered, you can select the entire song and click "Apply" to the "Noise Removal". Whatever was in the sample is the removed from the audio.

Initially, I thought this only applied to actual noise, but then I tried it on Drake's "Trophies" song, in which the horns are played first. Guess what? It extracted the horns from the entire song! It wasn't perfect and I'm sure if I toggled the options a bit I could get better results, but the concept made me very curious.

Is it possible to grab an "image sample" as the "noise" of an image and then select the entire image and simply delete that "noise"? And if you can do that with an image, then could you do that with video? What a simple way to extract grass or trees in the video above?

I don't know of such an option in After Effects, but does such an option exist at all? I'm sure graphics technology has advanced to the point of pattern recognition, so how easy would this option be, especially since it already exists in open source audio editors?

If you don't know how to do the above "get noise" option, then what other professional options would you use to extract the 3 soldiers from the video WITHOUT rotoscoping or roto brush tool?


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Tero AhlforsRe: If I don't want to Rotoscope or use the Roto Brush Tool... (discuss other techniques here)
by on Apr 14, 2014 at 12:33:46 pm

Difference matte works for locked down shots that have same lighting in them.

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Scott JohnsonRe: If I don't want to Rotoscope or use the Roto Brush Tool... (discuss other techniques here)
by on Apr 14, 2014 at 5:25:04 pm

Thanks for the reply. I tried Difference matte, but there's vertical camera movement in the clip, also I don't have a shot of the grass and background without the soldiers so I had to create such an image in Photoshop via the rubber stamp tool. Didn't get the best results, it even caused distortion/grass noise on the soldiers themselves.

- Scott

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