Keying problem

[bartrobinson]

Im using after fx 6.5 and have some footage of a person in front of a wall that is sky blue wallpaper. I would like to key out the wall, but as it is embosed paper, Im finding it a damn hassle to get done. Someone said there is a way using the diiferance key and taking some footage of just the wall as well and using that to help remove the wall in the main comp. Has anyone got any good suggestions for me. Thanks.

Ok, couple things. What do you mean by embossed paper? You mean there are shapes or something embossed into the paper? Anyhow, there's a few things you can try. First, could could try color difference matting, if the blue doesn't have too much green in it (kinda cyan or teal looking, which is kinda what sky blue is). If that's a no go, you might try a difference matte, which is best done with a locked off or motion control shot, where you have clean plates of the backing with everything the same except for the FG is missing. You might also be able to fake that if you don't have the clean plates with a plate that you paint clean. You can also use the two techniques together to get the job done by later mixing in the best parts of the mattes.

[Zander]

Ok, couple things. What do you mean by embossed paper? You mean there are shapes or something embossed into the paper? Anyhow, there's a few things you can try. First, could could try color difference matting, if the blue doesn't have too much green in it (kinda cyan or teal looking, which is kinda what sky blue is). If that's a no go, you might try a difference matte, which is best done with a locked off or motion control shot, where you have clean plates of the backing with everything the same except for the FG is missing. You might also be able to fake that if you don't have the clean plates with a plate that you paint clean. You can also use the two techniques together to get the job done by later mixing in the best parts of the mattes.

Thanks buddy, thats the line im going on. As for the paper. yes it is kind of like bubble wrap. Little raised bubbles on the wallpaper, which has made it difficult to remove simply with the colour key. As I do not have a greenscreen, the wall was a trial. I think in all honesty it might be better to try another more simpler approach, or a better bg. Many thanks for your input.

[dprgb]

Difference mattes don't work well with DV footage, since as it reduces the chroma information the noise introduced makes it difficult to get a clean difference matte.

Your best bet would be what I did - go to a department store and find a solid green or blue sheet (preferrably on sale) and buy it - experiment with that you'll be much happier.

[Zander]

Difference mattes don't work well with DV footage, since as it reduces the chroma information the noise introduced makes it difficult to get a clean difference matte.

Your best bet would be what I did - go to a department store and find a solid green or blue sheet (preferrably on sale) and buy it - experiment with that you'll be much happier.

Damn good idea. Cheers.

[beaker]

Also when I was younger I bought a bunch of green cloth and sewed it together to form a big screen. Just make sure to get rid of as many of the wrinkles as you can when you hang it. Sewing in a bar or a cable to the top helps a lot.

[bartrobinson]

Difference mattes don't work well with DV footage, since as it reduces the chroma information the noise introduced makes it difficult to get a clean difference matte.

Your best bet would be what I did - go to a department store and find a solid green or blue sheet (preferrably on sale) and buy it - experiment with that you'll be much happier.

Well, I don't suggest that difference mattes alone would work. They rarely work alone with good footage, but just used as a suppliment might get him further along than he was.

[thatoneguy]

Or if it's a pretty short shot.

*Drum roll*

ROTO!

I know... not the answer any compositor wants to hear, but unfortunately the one I've found myself resorting to time and time again.

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