correcting the "green screen glow"

Sr_C wrote on 4/28/2003, 6:14 PM

Does anybody have any tips on correcting the classic "green screen glow" that outlines objects shot in front of a green screen after keying the green out?

Note: I am still on Vegas Video 3.0c as I have not upgraded as of yet.

Thanks for any help. -Shon

Comments

Cheno wrote on 4/28/2003, 7:55 PM

get your subject farther from the green screen. Rule of thumb is as many feet as they are tall. Farther the better. Also, proper backlight on the subject will remove the green halo for the most part.

mike

Sr_C wrote on 4/28/2003, 11:31 PM

Actually, I meant to ask if there is anything you can do after the footage is already taken. Most of it came out good but there are a few shots that I need that have a slight outline. Any tips on correcting if reshooting is not an option?

bcgreen wrote on 4/29/2003, 12:17 AM

Here's a trick I use at work, but frankly I don't know how you would do this in Vegas, although I'm sure there must be a way:

Shrink your alpha channel just slightly-- enough to get rid of the glow. This will only work if the glow is slight, however.

Bryan

shogo wrote on 4/29/2003, 9:18 AM

I have the same problem with V4 on a subjects fingers when he moves fast. How do you shrink the alpha channel? This would help me immensely.

bcgreen wrote on 4/29/2003, 10:38 AM

Hmmm....I've poked around Vegas, and can't figure out how to do this. On the Avid D|S, the chroma key effect has an option which allows you to shrink the alpha channel. Thought there might be something similar in Vegas. Maybe there's a workaround I haven't figured out yet?

Bryan

watson wrote on 4/29/2003, 10:57 AM

Try using color correction on the clip and this can often tweak things out.
It is better to apply small improvements duplicating FX rather than one larger correction.

Your keyed in background makes a difference too so choose wisely.
W

Jason_Abbott wrote on 4/29/2003, 11:36 AM

DSE talks about this in his Chromakeying tutorial (specifically third paragraph from last).

bcgreen wrote on 4/29/2003, 12:10 PM

That's true...you could use selective color correction to desaturate green only...

shogo wrote on 4/30/2003, 10:26 AM

I notice there is slight DV compression artifacts around fast moving objects could this be fixed be deinterlacing the footage before applying a key to the video? Everything else is fine it just happens around the edges of (moving objects)and if you look closeley you notice little blocky artifacts. Was wondering if deinterlacing would help remove this.