Deleting backgrounds using After Effects

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Deleting backgrounds using After Effects

Postby Sierra Lorna » Tue Oct 08, 2002 11:16 pm

I've heard that it's possible to easily remove backgrounds from a scene using Adobe After Effects. How does that work? The only way I see possible of accurately deleting backgrounds is by erasing them by hand, frame by frame, in Photoshop. It'd be good to know if there's an easier way or not.

And while I'm at it, is After Effects even worth the buy?
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Re: Deleting backgrounds using After Effects

Postby segaismysavior » Tue Oct 08, 2002 11:30 pm

Sierra Lorna wrote:And while I'm at it, is After Effects even worth the buy?


Not unless you either read the entire manual before using it, or buy a book and read up to see if it's your thing.

I personally love that program, but it's not for everyone.


And answer time:

technically yes you can remove the background by creating a mask and animating it around the edge of what you want to keep. Is this easy? hell no, and probably not worth learning and using unless you're really good at it.

Best to stick to Photoshop if you're familiar with it.
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Postby klinky » Tue Oct 08, 2002 11:32 pm

There is no easier way, unless you have a extremely plain background like a single color then you're screwed. What you could do is make a film strip and import it into Photoshop. Then you enable mask mode in photoshop scribble out your mask. Then just copy and paste it on the remaining frames, you'll probably have to do some minor adjustments, but it's alot easier then filling everything back in each time.

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Postby Akashio » Wed Oct 09, 2002 1:01 am

klinky wrote:There is no easier way, unless you have a extremely plain background like a single color then you're screwed. What you could do is make a film strip and import it into Photoshop. Then you enable mask mode in photoshop scribble out your mask. Then just copy and paste it on the remaining frames, you'll probably have to do some minor adjustments, but it's alot easier then filling everything back in each time.

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How does one enable 'mask mode' in photoshop 6?
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Postby klinky » Wed Oct 09, 2002 1:35 am

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Mask Mode = teh l33t. Just copy and paste while in mask mode ;p


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Postby alternatefutures » Wed Oct 09, 2002 7:21 am

Well, if you're using photoshop you may as well erase the entire backround instead of just creating a matte. That way you can also use photoshop's image adjustments on select parts to remove color bleeding. Without doing this the effect will look like crap anyway.
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Postby klinky » Wed Oct 09, 2002 7:51 am

Oh by all means you want to erase the background. When making a matte you just color in what you want to keep(or you can color in what you don't want and then invert the matte). Then go back to regular editing mode and what you didn't color in will be selected and you can just hit Del. The idea is to copy the matte while in mask mode and then paste it onto your subsequent images. Then you can just make slight adjustments to the matte and then delete again.

If you just used the eraser then you'd have to go through the entire process over again, erasing the junk areas. I've done it before and it's time consuming :\


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Postby alternatefutures » Wed Oct 09, 2002 12:21 pm

Oh, it takes me all of three seconds to erase junk areas when I use the eraser: Ctrl-click the layer, create alpha channel, select good portions, expand election by 2, invert, delete. Make this into an action and it takes almost no time at all. I just use the eraser instead of the mask because I find it to be a little more accurate and you only have to worry about the edges. Even with the mask you need to completely cover the area you want to keep. Of course, if we were really smart we'd be using vector paths in After Effects to mask... oh well :)
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Postby klinky » Wed Oct 09, 2002 3:40 pm

I wouldn't really use vector paths since ergh. Would be inaccurate and really doesn't add alot of flexibility, especially if you want to keep more then one object.

A mask/matte is a alpha channel :\

You shouldv'e just suggested your method instead of confusing klinky by stating you just erase it all ;p

You can use any tool you want in mask mode, you can even use shapes to define parts ;p I don't see your eraser tool doing that :p



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Postby alternatefutures » Wed Oct 09, 2002 5:05 pm

But if I didn't confuse you it wouldn't be fun, now would it?
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Postby Sierra Lorna » Wed Oct 09, 2002 8:20 pm

So, this mask mode thing just enables you to make the background a transparency in Premiere, right? I could try doing that for some parts, because it might work better. But for now I guess I'm stuck with that good old eraser.

I'm kind of glad to hear that After Effects doesn't work much better than Photoshop, since I can't afford it anyway. :wink:
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Postby klinky » Wed Oct 09, 2002 8:46 pm

No no, the idea is to export a filmstrip of what you want from Premiere. Filmstrips are uncompressed frames that you can view all at once when in Photoshop.

The idea is to make a single mask for the first frame. Then you can copy and paste that mask to the 2nd, 3rd, 4th... frames. Then make slight adjustments where needed. Usually the thing you're trying to remove will be in a similar spot/position, so you would only have to make some minor adjustments to the mask, instead of redoing the whole thing for each frame.

You want to do the least amount of boring work as possible and erasing crap is boring :p


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Postby alternatefutures » Thu Oct 10, 2002 2:20 pm

Wait, how does that work? Filmstrip files are supposed to be very sensitive to format changes and I don't think they can support transparency, so how are you doing it that way? Plus they're so huge you must be using a very fast machine to do this work, otherwise you're slowing yourself down.

Now, bitmap sequences I can understand. I'm just curious how you actually mask a filmstrip.
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Postby klinky » Thu Oct 10, 2002 4:28 pm

Hey man, I finally tested what I was spouting about and you sir ARE correct :\ Though I don't like to admit it. My thoughts were conceptually sound but failed at the final stage, it would work if you could actually manipulate the alpha on filmstrip, but you can't. :|

Still you could copy masks/alpha. Between bitmaps. Shux :{ stupid filmstrips. Though if I figure something out I'll let you know. Once again Adobe fails teh klinky :{


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Postby klinky » Thu Oct 10, 2002 4:34 pm

Ooooh, well technically you could still use a chroma/green screen key on a film strip :}

Tho I like pure Alpha Channels better. This would really be a, which ever one is quicker for you type deal.


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