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background subtraction live camera video

Jun 19 2010 | 11:45 pm

I have two cameras recording two separate videos
I would like to subtract the background in both videos and only leave the people in the video remain. After subtraction, I would like the background of the video to be transparent (like a .PNG pic). I tried a few patches here but all the patches make the background black instead of transparent.
question 1: how to make the background transparent
question 1: once the background in both videos are subtracted and being transparent. How to add the two videos together and make a third video? (i guess i can use jit.op?)

Jun 22 2010 | 7:24 am

please help! or this is impossible to do? Thanks

Jun 23 2010 | 2:43 pm

Hard to comment without seeing a patch.

I don’t know how to check if a video has a transparent alpha channel short of putting it into something like flash and seeing which parts disappear. I don’t have much experience with video transparency. But the experience I do have is simply making a simple alpha channel with jit.matrix @planemap 2123 (making something like the green channel your alpha info), then when you do an alpha blend, boost the Alpha plane with jit.scalebias @ascale 50 (or more) to make it less ghostly.


Jun 24 2010 | 6:08 pm

Background subtraction is complicated, but you can use objects like jit.chromakey or jit.lumakey to do simple keying if you have a solid-colored backdrop. There are a couple of Jitter Recipes that deal in alpha channel creation and usage. I’d recommend checking those out. For the actual blending, you might check out jit.alphablend or using OpenGL.


Jun 27 2010 | 3:21 am

Thank you Cap 10subtext and Andrew Benson for the help.
I subtracted the background by using jit.chromakey and And superimposed two videos using

Mar 19 2012 | 6:50 pm

Reviving an old post…

I’m planning do the same as you did. Have you successful accomplished blending one video and live camera? Can you help me whit some tips?


Luis Marques

Mar 20 2012 | 5:21 pm


Mar 21 2012 | 2:06 am

jit.op would do .

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