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How to replace a plain background with another…
I want to remove a background of a lecturer, he has a green shirt, and a yellow back ground ( smooth pained wall) to effectively create a transparent background the way you can in photoshop.
I want to replace the back ground with videos / images of the subjects he is speaking about….
Would it help if the background wall was a white ?
I have experimented with the channels but can do it…
thanksJoseph D
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8 Replies
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The yellow wall behing him creates a problem. Normally the background is green or blue as there is neither of these colors in human skin. You can key out the yellow but that may cause any yellow in his/her skin to be transparent. Try it and see, add chromakey filter, eyedrop the color of the wall and move the sliders and see if you can do it. Danny Hays
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Thanks
The filming has only just started so I can change the back ground to green/ blue.
The back ground needs to be replaced by video scenes of forests and rivers
Does it matter if the clothing is a different/ same colour as he back ground? I guess white is best ?
I have looked at the Chroma keyer, I am not sure how to use the dropperI gues then one needs to use the aplha channels to superimpose the speaker onto the forest scenes?
ThanksJoseph D
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Ideally, You would put the actor in front of a green screen and the actor should not have any green on him. Also the Vegas chromakey pluggin doesn’t have spill supression so you should get as much space between the actor and the green screen as to not get any green spill on the actor. If you don’t have access to a better keyer like Keylight or Ultra, you can backlight the actor with a magenta light. That’s the oposite color of green and can help reduce the visable green spill from the backgound. Also if your shooting DV, you’ll get better results in Vegas if you put a chroma blur pluggin before the chromakey pluggin in the chain, and set the blur to medium. This helps reduce the jaggies typiclly found when keying DV and its 4.1.1. color space. Hope this helps, Danny Hays
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Thank you,
1. Should I get a better pluggin? Where can I get one?2.What does back light mean, you mean you shone a ‘magenta’ light behind the speaker, ………..if so, does the magenta light have to illuminate the silhouette of the speaker in a certain way?
3. Shooting DV ? Yes I am using miniDV… on a HD camera
4. What is 4.1.1.?
5. Jaggle? is that a technical term for ? jagged edges?
6. Do I need to use an alpha channel setting other than…’source alpha’ for the lecture’s video track, ie should I be using… ‘overlay’, or ‘ lighten’….
since I need to be using a second video track ( of forests/ mountains etc) as a back ground……………many thanks
JosephJoseph D
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I have done it, but it seems that no matter what you do with the sliders, and the blur , you are left with some residual flickering black artefeact
( By the way the speaker was wearing a black shirt, perhaps a white shirt will blur more inconspicuously)
I can not totally remove the artfects, whick look like bits of black clouds flickering in the background, Is this because the Chroma Keyer in Vegas is not precise enough?
Joseph D
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If the lighting is good enough you can make it work. Yes the magenta backlight is to color, or cancel out I should say any green spill that may be getting on the back, soloette of the speaker. I’ve had problems with black shirts and artifacts too. White is better but will show green spill well. If you backlight the speaker well enough white will work. If you have some small samples of the video you can send me I can experiment and give you the best settings for the keyer I can find. HD video should allow for alot better keying than DV. 4.1.1. is a term for the color sampleing of DV. Do a google serch on it for details if you want. Your HD video is probably 4.2.0. You can convert the video in Vegas to Cineform avi which is 4.2.2 and will key even better.. Again some small samples will help. Danny Hays danhays2004@yahoo.com
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Thank you for the offer
I am still trying to get the green back ground, but I cant find a magenta light as I am in a remote desert areaJoseph D
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I use a Megenta Gel in thosse cases.
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