Can't Get Good Result With Chroma Key?

Ken-Theriot wrote on 6/28/2021, 5:58 PM

I've tried so many different lighting setups and then different techniques in Vegas Pro (16), but can't seem to get a satisfactory result with a green screen and the Vegas Chroma Key tool. I actually got better results ca 10 years ago than I seem to be able to get now.

Some of the main things that are different are that I now have a better camera (Panasonic Lumix G7) and better lighting (pair of Viltrox VL-S192T lights for lighting myself. For the green screen, I have tried several different kinds of lights that I had - some CFLs in dome shells, then some RX-8T 16W Mini LED Light Dimmable 5600K lights. And today I tried a trio of lights - Altson Led Video Lighting Kit Dimmable 5600K (USB powered) ones. And they didn't work very well either.

the problem I'm having is that no matter what I do, I can't seem to key out green screen. I just get a semi-transparent blue color instead. I've tried adjusting the low and high thresholds to make the blue go mostly away. But the best I can do results in the edges of my face (etc) not looking smooth. They are sort of blocky. Either that, or there is tremendous color-cast "outlining" my head.

The amazing thing is that with Zoom, the green screen works PERFECTLY. I don't even need to light the screen separately. The lights on me seem to be enough.

So I'm wondering if maybe the built-in chroma key tool in Vegas Pro 16 just isn't very good? If so, is there a better, 3rd-party one? And if not, I imagine it has to be a screen lighting problem. But I've tried everything I can think of. I have so many lights not that it's getting ridiculous. And the only recommended thing people are saying is to get these long lights and do all kinds of DIY to attach them vertically to stands and put them on either side. But with all the experimenting I've already done, there is no guarantee this will work either.

One other thing I wonder about is the color temperatures. The lights I've gotten to light the green screen have all been 5600K. But to light myself, I have adjusted the Viltrox temperatures down to 5000K, which looks much better on my face. Could that be contributing?

I know this is a lot of questions :-P. I wonder if maybe someone could point me in the direction of a good tutorial. It feels crazy, since I've been doing green screen/CK stuff for more than 10 years. But the results are just getting worse and worse for some reason. Thoughts? Advice?

Thanks!

Comments

Musicvid wrote on 6/28/2021, 8:52 PM

Guess we'd need to see some grabs, your chromakey settings, and lighting setup, Ken. If by chance you're using green fabric, it won't work.

Ken-Theriot wrote on 6/28/2021, 9:38 PM

Thanks Musicvid. I'll post some grabs, etc. tomorrow. As for the screen I'm using the Neewer Chromakey Backdrop - Double-Sided Green Screen and Blue Screen, 2-in-1 Collapsible and Reversible Background. Since that was purpose-made for this, I assume that's not the issue?

Musicvid wrote on 6/28/2021, 9:40 PM

Since that was purpose-made for this, I assume that's not the issue?

That is correct. It is cotton and rayon that reflects at the wrong ends of the spectrum.

Vdanny wrote on 6/28/2021, 10:40 PM

Hi @Ken-Theriot,

I have always used third party chroma key software with Vegas as I found it difficult to get a decent key with the native one under less than perfect lighting conditions. I mostly use the Boris FX BCC Chroma Key plugin which has been offered as part of BCC Key & Blend with Vegas upgrades. This plugin has many ways of getting a quality key and cleaning up unwanted light spill. The chroma key in Hitfilm which integrates with the Vegas timeline or their FXHome Ignite plugin offers a very high quality chroma keyer. One basic thing to do is make sure your subject isn't right next to your green screen. Have them a least 3 or 4 feet in front.

Ken-Theriot wrote on 6/28/2021, 11:08 PM

Thanks Vdanny! I suspected as much. I have 3-4 feet between me and the screen. And I'll try one of the other tools. Thanks!

Ken-Theriot wrote on 6/29/2021, 11:28 AM

Thanks Musicvid. I'll post some grabs, etc. tomorrow. As for the screen I'm using the Neewer Chromakey Backdrop - Double-Sided Green Screen and Blue Screen, 2-in-1 Collapsible and Reversible Background. Since that was purpose-made for this, I assume that's not the issue?

OK, here are some pics. The angles make it hard to see how far things are from each other. So for reference, the lights are about 2 feet back from the screen. And the back of the chair is 3-4 feet from the screen.

Here are a few pics from within Vegas Pro. The first is with no Chroma Key effect. Yes, I see the lighting is not even. But the problem exists even across areas where the lighting is relatively even, like in a radius around my head.

 

As you can see, even in the relatively even area around my head, there is no combination of settings that yield a good separation. In the pic with no Chroma key, I notice a BUNCH of green cast mixing with my hair. I've put the screen back as far as 4-5 feet and still cannot eliminate this. That is surely at least part of the problem. Though I can't even get a good separation around my black shirt. So there is something else majorly wrong and I can't figure it out. Hopefully this helps paint a picture of my setup and efforts. BTW, the middle pic is with Chroma Key applied with default settings (no Threshold adjustments) using Green or Pure Green yields same result. Then I used the dropper to grab the exact green shade from around my head. The pic on the right is with the best combo of threshold adjustments I could do.

Oh, and here are the lights for the subject (me) as seen from my chair.

Vdanny wrote on 6/29/2021, 1:32 PM

Hi @Ken-Theriot,

It is, of course, ideal if you can light the background and subject separately with the subject being the more brightly lit. I am surprised with the amount of green spill on your hair considering the distance you are from the screen. Are you shooting in UHD to give the chromakeyer the most detail to work with?

Ken-Theriot wrote on 6/29/2021, 2:24 PM

Thanks Vdanny. I definitely am lighting my screen separate from my subject. And the lights on me are MUCH brighter than on the screen. I am shooting in 4K with the G7.

Vdanny wrote on 6/29/2021, 3:10 PM

Hi @Ken-Theriot,

I believe there are trial versions of the plugins I was mentioning, as well as others. It seems that the native chromakeyer isn't giving you anywhere near the quality you should be getting with your setup.

jetdv wrote on 6/29/2021, 4:15 PM

I got this using the NewBlue Chroma Key effect. But you have a lot of green in your hair... (just used a "red" background")

Ken-Theriot wrote on 6/29/2021, 4:45 PM

Thanks jetdv. That helps. I can tell because the shirt is much more crisp on the edges. I don't know exactly how to get the green out of my hair. It may not be the full root cause. But it is DEFINITELY a huge part of it. I'll try a few things to at least get rid of the green in my hair. If I manage it, I'll post back with a pic and what I did. Thanks again!

Vdanny wrote on 6/29/2021, 5:29 PM

Hi @Ken-Theriot,

Do you have room enough for a back light?

Former user wrote on 6/29/2021, 5:38 PM

Don't try to chroma key the whole screen. Just concentrate on keying out around your shape. Then use MASKING to clean up the rest of it. As long as it is lit that unevenly, you will have these problems. And there is a lot of green in your hair. Use a backlight pointed toward the back of your hair to override the green cast. Tilt the green screen down a bit in case to help with the green reflection.

Ken-Theriot wrote on 6/29/2021, 6:10 PM

Thanks Doug. Yes. I've absolutely been doing that.

Ken-Theriot wrote on 6/29/2021, 6:10 PM

OK. I made several changes (still using the Vegas Chroma Key tool) and here is the result. First, my hair is no longer green (that I can see). Or it's certainly much LESS to the point I can't notice. I did this by moving the screen back as far as I could, between 4-5 feet now. Also, there are 5 lights on the screen and they are further away from the screen (about 3 feet). As a result, the screen is more evenly lit.

I noticed the bottom corners were still a little dark, so I moved those lights closer. Then I applied the chroma key with the threshold adjustments. I also used masking to crop close around my body. The face/head and skin look great now. HOWEVER, there is still a blue line around my black shirt. I have no clue how to get rid of that. Thoughts?

I looked at the BorisFX chroma key plugin, which doesn't look like you can JUST get the plugin for that. I'd have to pay for Continuum, which is just way too expensive for how often I do green screen stuff.

Vdanny wrote on 6/30/2021, 12:25 AM

Hi @Ken-Theriot,

The nice guy at Scrapyard Films has a way to get the NewBlue Chroma Key Pro plugin working in Vegas for free and legally. He describes how here:

It does offer a good set of tweaking controls for getting a clean key.

 

Reyfox wrote on 6/30/2021, 1:26 PM

You can also look at this video:

Ken-Theriot wrote on 6/30/2021, 1:50 PM

Very interesting. Thanks.

Ken-Theriot wrote on 6/30/2021, 1:51 PM

I'm quite happy with everything now EXCEPT I'm confused as to why it put a blue outline around my black shirt? Do I need to wear a lighter color shirt? I wouldn't have thought keying out green would cause an issue with a black shirt.

Ken-Theriot wrote on 7/1/2021, 5:46 PM

I think I may know why my shirt was outlined in blue. I noticed my shoulders were a bit blurry on the edges, which is to do with the narrow depth of field on this camera (G7). It's set to AF on my face and as short a distance back as my shoulders are from my face, it seems to be enough to introduce a slight blur on the edges. Is there a way to sharpen JUST a portion (say bottom half) of something in Vegas Pro? If I could sharpen the shirt, leaving the face alone, that might help.

Ken-Theriot wrote on 7/1/2021, 7:57 PM

Hi @Ken-Theriot,

The nice guy at Scrapyard Films has a way to get the NewBlue Chroma Key Pro plugin working in Vegas for free and legally. He describes how here:

It does offer a good set of tweaking controls for getting a clean key.

 

Vdanny, thanks VERY MUCH for this tip. It works much better than the native Vegas Chroma Keyer.

Ken-Theriot wrote on 7/3/2021, 1:04 PM

Vdanny - do you know if I have to keep Media Composer installed in order to continue to use the NewBlue Chroma Key Pro? It seems to take up a massive amount of space.

misohoza wrote on 7/3/2021, 1:29 PM

Vdanny - do you know if I have to keep Media Composer installed in order to continue to use the NewBlue Chroma Key Pro? It seems to take up a massive amount of space.

You didn't even need to install it. It just needs to be registered to your avid account.

Ken-Theriot wrote on 7/3/2021, 5:04 PM

Awesome! Thanks. I will uninstall it. Thanks again for the tip. the tool works really well :-).