Removing background color on After Effects CS3

[Darby Edelen]

You need to have some way to form a matte for the background, whether its by rotoscoping (drawing masks by hand, frame by frame or close to it, search the COW for more info), luma keying (removing/keeping information based on the brightness of the pixels) or chroma keying (removing/keeping information based on the color of the pixels).

The best results usually use some combination of the above techniques, and each one has its own tricks.

However, these work much better if the footage was shot with the intention of removing the background (green or blue screen for example), it gets much harder without steps taken during shooting.

Darby Edelen
Designer
Left Coast Digital
Santa Cruz, CA

[Pat Jaeger]

hi and welcome to the cow and after effects!

Firstly the background you speak of is it a consistent colour or one that varies. If it is consistent you may have a chance of getting rid of it fairly easily but ill need to know what its like first. If it is an uneven or many different colours you will have to rotoscope it frame by frame. Incase you dont know, rotoscoping is basically drawing around the subject with the pen tool frame by frame to separate it from unwanted parts of the shot (the background in your case).

[Pat Jaeger]

lol Darby explains it much more clearly than I did, his advice is more useful for you i think 🙂

[Joe Sadikin]

Thanks, guys, for replying!!

I will try do rotoscoping because the background was a green chalkboard — BUT you can even see the wall (white) at the bottom of the board (wow…I just realize how amateur I am) lol O_0

Two more question, guys.

How do I do rotoscoping in After Effects? And after I do that, what should I do if I want to put a background (say, jpeg) on the footage?

Thanks very much 🙂

[Joe Sadikin]

Thanks, guys, for replying!!

I will try do rotoscoping because the background was a green chalkboard — BUT you can even see the wall (white) at the bottom of the board (wow…I just realize how amateur I am) lol O_0

Two more question, guys.

How do I do rotoscoping in After Effects? And after I do that, what should I do if I want to put a background (say, jpeg) on the footage?

Thanks very much 🙂

[Michael Nowakowski]

Well not having seen your footage my suggestion is going to be limited. Watch Andrew Kramers tutorial on advanced sky replacement. The tutorial shows you how to replace a sky but I’ve had success with replacing other sorts of backgrounds using this method. In my opinion rotoscoping is a last resort. The amount of time it takes to go frame by frame to get rid of the background experimenting with different technics is worth the effort

[Darby Edelen]

If there is a green chalkboard then you should look into using chroma keying (try Keylight) to remove it, then you could try using luma keying to remove the white wall below it, and use rotoscoping as a final step to ‘fix’ the problems in your keyed footage.

There is at least one tutorial on rotoscoping in the AE Tutorials section of the COW.

Darby Edelen
Designer
Left Coast Digital
Santa Cruz, CA

[Amir Sharafeh]

If your subject is to the side of the frame and is a close up, try a junk matte, which is a generic mask around your subject to minimize the BG (background) colors. If you can minimize it to one color (chalkboard), you’re good to go. Also, one thing that might help pulling the key is to bump up the “levels” on your footage, pre-comp the footage with your new levels, then keying out the green. Chalkboard green is really dull, hence suggesting bumping up levels. Once the key has been set, you can make a matte out of it by having the normal footage (the unmodified levels footage) replace it. All in all, it would be nice to take a frame and post it for more specific help.

[Ricardo Hubbs]

Hello….!

I am wishing to remove a black background from a stock footage clip of flowers growing in slowmo. I thought a composite mode would work and leave just the flowers to superimpose onto the layer below… hmmm.

suggestions?

cheers,
ricardO

[Christina Gaddy]

I just wanted you all to know that if you have you object on a solid BG, you can go the the Effects & Presets window and choose Color key. This will give you a color picker or eye dropper. Take that and select the BG color, it will be taken away, you may not see that it is if you used Black. You will see it when you transfer it over to the scene you are trying to use it in. There is an edge thin and an edge feather that you may need to adjust, but this is a fast way to get it done. 🙂 I hope this helps you out. It took me lots of searching before I found what i ws looking for. I had forgotten what it was called, so I looked it up online and could not find it, so I thought I would share.