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Needing some advices in chroma keying.

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Serban Andrei
Needing some advices in chroma keying.
on Jan 14, 2014 at 1:48:12 pm

Hello,

I am new to video editing, and right now i am in a bit of a dilemma, because i think i'm doing something wrong and i'm not getting the result i want.
So this is what am i trying to do: I'm filming a subject presenting some products on a green screen. I am removing the green screen using after effects, and replacing it with white.
I think i'm getting a good key but the problem i have is that the final footage has background noise and just does not look the way i wanted and the quality is clearly different from other videos i found on youtube that use the same chroma key tehnique.

This is the equipment i am using at the moment:
I am shooting with a Panasonic AG-AC130P, and i have 4x FV H1000 220V 1000W lights, 2 of them in front of the subject, and the other 2 between the subject and the green background, lighting the background so i don't get shadows.

This is a link with a video that i made:




And this is an example of a video i found on youtube and looks a lot better:





I think i am missing something, maybe i don't have all the equipment i need, maybe i need different lights, or maybe i'm doing something wrong in editing.

Maybe someone with more experience than i have can give me a tip or two.

Thank you.


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Chris Evans
Re: Needing some advices in chroma keying.
on Jan 14, 2014 at 4:00:18 pm

In your video that you posted, the key actually looks pretty good. It is a little soft, but not bad at all. To minimize noise, make sure your gain is low on the camera and that your BG is well lit and exposed correctly and not too dark because noise appears in the dark areas. Expose for the greenscreen, then light your actor accordingly. Your lights and camera are fine, I have the same camera and I do green screen work.

In after effects, make sure you are using Keylight. Pick a good color and don't adjust your Screen Gain and Balance too much, rather, use the Clip Black and Clip White under the Screen Matte section. One of the best and probably underutilized Views in Keylight is Status. In that view mode, the white pixels are fully opaque, the black pixels are fully transparent and the grey ones are semi transparent, but could be anywhere from 1% transparent to 99% transparent. Make sure there are no grey pixels over your background or your subject, but there should be a small grey area around the edge of your matte and a slightly larger area over the edges of the hair.

If you are doing all those things right, there shouldn't be any noise over your BG. However, if you are going to do a white background and you know it, it's easier to just shoot it that way if you can.

I hope this helps.


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Serban Andrei
Re: Needing some advices in chroma keying.
on Jan 14, 2014 at 4:43:26 pm

Thanks Chris, i'm going to do what you said and come back with a post. I was thinking about buying a white canvas background or just shoot my subject in front of a white wall and skip the chroma key process but i'm afraid i will not manage to light my white background properly so that it will look pure white. Do you think it's possible?


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Chris Evans
Re: Needing some advices in chroma keying.
on Jan 14, 2014 at 5:51:47 pm

I don't know how soft the lights you have are as I have never used them. The only time I've seen an actual white BG setup, all the light was through a huge white screen above and in front of the actor (it was a full body shot, though). I would think that if you can get an even enough light across the BG and there aren't shadows, you should be able to do it the same way you do your green screen set up. Since you aren't keying it, though, every shadow and discrepancy will be noticeable. That being said, it's easy to do some work in post with a simple mask around your subject and a white solid if the shadows aren't directly behind your talent. With white, it will be a lot easier if it is solid because you'll have to stretch a cloth background a lot to get rid of all the wrinkles (if there are any).


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Darby Edelen
Re: Needing some advices in chroma keying.
on Jan 16, 2014 at 6:13:18 am

The other suggestion I'd make if you decide to go with a practical white background would be to light it significantly hotter than your subject. Expose for the subject and let the background blow out. Personally I'd go that route if I have the lights for it and I know that the background is going to be white.

As for your shoot I honestly couldn't see much noise in the background at all. YouTube's compression (and my dirty screen, jeeze, when was the last time I cleaned this thing?!) probably help you there.

The other few suggestions I'd make are a matter of opinion so feel free to ignore them :)

It looks like you already have some backlight but a bit more might add to the look of a white hot surface behind the subject. I'd also recommend trying to move the fill light a little farther away from the camera if possible to avoid at least one of the reflections in the subject's glasses.

The editing in the SourceFed example you posted is much faster and adds some excitement. However, achieving that would probably require additional cameras, additional takes, or a high resolution digital cinema camera for "push ins." If you have the time to experiment with some more coverage of close ups that might help maintain visual interest.

Darby Edelen


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Serban Andrei
Re: Needing some advices in chroma keying.
on Jan 17, 2014 at 9:24:41 am

So i set my gain to low on my camera and i have used the Status view mode on the keylight effect and removed the background only with clip black & clip white. This is how the video looks(you can skip the first 30 seconds and watch it from the moment he sits at the table):






The background looks ok, the edges of the t-shirt look ok, but what i do not like are the edges of his skin...they are a bit glowing, and also i have some noise on the t-shirt, and i really don't know what to do about it, i'm using Denoiser in After Effects for noise reduction, it takes some of it out but not enough i think.

Thanks for the suggestions Darby, i didn't have the chance to apply them but yes, i will try to move one of the lights so it does not reflect, i don't have much space to work with but i will do my best. Also, what do you mean by "expose for the subject"? Chris said in his first post "expose the BG correctly" but i can't seem to understand.

Yea, the editing in the SourceFed video is much faster, but for now what i am trying to achieve are just that type of colours, that cut, and just the general image which for me looks really nice and clean, nothing more.


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Darby Edelen
Re: Needing some advices in chroma keying.
on Jan 17, 2014 at 4:00:12 pm

[Serban Andrei] "Also, what do you mean by "expose for the subject"? Chris said in his first post "expose the BG correctly" but i can't seem to understand."

That advice was specific to using a white background instead of green screen.

[Serban Andrei] "they are a bit glowing, and also i have some noise on the t-shirt, and i really don't know what to do about it, i'm using Denoiser in After Effects for noise reduction, it takes some of it out but not enough i think."

Try using the Intermediate Result from keylight instead of the Final Result and using another method to despill the green. The despilling in keylight can introduce noise.

Darby Edelen


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Chris Evans
Re: Needing some advices in chroma keying.
on Jan 17, 2014 at 4:32:58 pm

I think your video looks good, however, I'm not gonna lie, your edged do make it look a little bit amateur. A few ideas: try to keep your screen softness as low as possible (ideally below 1), play with your Screen Shrink/Grow to get rid of the strange edges on your table and around his skin (you can go even to -5 or -6 and it nobody will notice), also apply some sharpening to your image (just use the sharpen effect, probably around 30, and make sure it is below or applies after your keylight), also, you don't need to worry about the noise on his shirt, I can't even see it (could be the YouTube compression, but even if it was that means it isn't enough to worry about).

Here are some other thoughts that I think will make your video look more professional. (NOTE: these are just my opinions) If there was any way you could remove the tint on his glasses or have him not wear them. If he could stand or sit on a stool instead of a chair with a back, he would look like he has better posture and not lean on the table as much.


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Serban Andrei
Re: Needing some advices in chroma keying.
on Feb 5, 2014 at 6:10:23 pm

Thanks for the tips guys. Sorry for not replying. So this is what i managed to achieve in the meantime, this is the last movie i made.







I think that black t-shirt is ruining the footage that the camera is filming. It's visible in this video that when the zoom goes to his black jeans, the imagine is not looking good. I tried to move the lights a little bit to remove the reflections in his glasses but i think i do not have enough space to work with in the room or i just don't know where to put them. Also, i don't know another method for keying besides "keylight" is there any?

Please tell me how it looks. Thanks


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Chris Evans
Re: Needing some advices in chroma keying.
on Feb 5, 2014 at 6:49:02 pm

That is a very good, clean key. If you don't have the room, don't worry about the light reflections to much, they aren't that bad. There are other things you can use to key, but keylight is up there with the best of them. Getting something different won't help you get a better key, it would just be a different way to get the same key. And they cost money. (keylight does if you don't have after effects, but you do, so it's free). With what you have, I don't think you can get much better, good job!

I am going to mention one more thing though and is just something to think about, not a real issue except to people like us. Your camera doesn't have a lot of detail. Most noticeable in his beard. That, for me, is the only thing that really takes your video away from looking very professional. Again, not a big issue, just something to think about if you continue doing this for a while.


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Serban Andrei
Re: Needing some advices in chroma keying.
on Feb 5, 2014 at 7:31:10 pm

Thanks Chris, i am using the "Denoiser" plug-in, is it possible to influence the footage detail? Because when i apply the effect, it ads a bit of blurriness to the image. I am going to do film editing for a while, atm i am not thinking about a new camera. But for the future, what should i look for at a camera? As for the camera, it's a Panasonic AG-AC120EN.


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Chris Evans
Re: Needing some advices in chroma keying.
on Feb 5, 2014 at 7:42:33 pm

That's not a bad camera, I have one very similar, even Panasonic. It probably is your denoiser. Try making one without it, but don't judge the noise till after you put it on YouTube. It may not be as bad as you think. Sorry if I'm going to far, it's just stuff I would try.


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Serban Andrei
Re: Needing some advices in chroma keying.
on Feb 5, 2014 at 8:03:40 pm

It's not a problem, don't worry about it. I posted here hoping to get advices from people with more experience than me. I will definitely try that and come back with a post, thank you.


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Serban Andrei
Re: Needing some advices in chroma keying.
on Feb 24, 2014 at 11:49:53 am

After numerous changes, but unsatisfying results, i dropped the chroma key process along with the green screen and moved my subject in front of a white wall. I had some problems with shadows and proper amount of light on my subject, but i bought 2 umbrellas. Seems to be a good choice, i'm now using just 2 1000W lights instead of 4. I placed them in front of my subject and this is the result so far:







I am pretty happy with this, but still i have one big issue. Noise, can't seem to figure it out...my gain in low on my camera, my subject has enough light but the footage still has noise. After i uploaded the video to YouTube the noise looks a lot worse, in the footage from my computer it's clearly better. Another is that i would like my background to be closer to white. Right now i am thinking at a decoration of some sort in the background...with some posters, boards and maybe a big TV. I don't know how is going to look and i am afraid that the lights will be reflecting from the TV..but i am going to try. And still...until i get somewhere with the decorations i would like to make the background closer to white.

Some thoughts? Thanks.


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Chris Evans
Re: Needing some advices in chroma keying.
on Feb 24, 2014 at 2:56:21 pm

I just watched the video on YouTube at full quality and I could barely see any grain even when I was specifically looking for it, so don't worry about that too much.

The only way to make your background whiter is to throw more light on it without putting any on your subject. I don't know what kind of lights you are using, but if they have barn doors, you should be able to put them level with your actor (or even a little in front), out to the side of the shot and point them at the background without getting any on your actor. Since you are only using 2 of your lights now, that should be easy. Move your actor as far forward as you can and still get the shot and that will help spread the lights evenly over the BG. If you can't get it even, just point the lights at the center and it will give you a natural vignette and nobody will even notice.

I think your video is actually really good. I like the white background and it looks great overall. I am a little distracted by the lights reflecting in his glasses, but that isn't too much of a problem. Be proud of yourself, this is a quality product.


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Serban Andrei
Re: Needing some advices in chroma keying.
on Feb 25, 2014 at 2:09:17 pm

Thank you Chris, i am proud of the result but i want to make it better. I don't know what it is but after i uploaded the footage on YouTube, it got a lot worse, maybe isn't noise, but i don't know how to call it. It looks like it's pixelated or something, it does not look HD, and i am sure of that because i can see the difference between the footage from the PC vs YouTube. Maybe it's YouTube's compression or i have to convert my video in some other format. I saw videos that look better than mine on YouTube, and i am sure that they were filmed with a inferior camera.


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