Remove a Color work with green only?

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  • Updated 2 years ago
I've successfully used Remove a Color when I used a greenscreen as the backdrop, but in my current project I used a light blue paper roll for the background -- assuming I could remove that color too. Not so: when I use the Color Picker, it picks up the blue background -- along with the shirts my subjects are wearing (one black, the other black and green.

So: Is Remove a Color only functional for the color green? And if not, what's going wrong for me?
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Posted 2 years ago

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Joe Morgan

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So catkins , first off,

It’s impossible to assess the actually quality of your footage from an image posted to this forum.

Blue backdrops should be extremely blue, much more so than yours is.

Common DSLR’s and Camcorders don’t record/compress bluescreen media as well as they do green screens.

So that’s another obstacle you’re probably facing. If your shooting with a $2,000+ camera. Set to high quality. Then compression probably isn’t an issue.

Next issue....... The characters are positioned too close to the wall. Their casting shadows. You want some distance between the wall, your actors and any props. You want enough free space to direct light on the wall or backdrop and cancel out most of the shadows.

Plus, when your too close to a colored backdrop. The color will reflect back upon you. Mainly around the outer edges of your silhouette.

  So when you go to remove the background, the outer edges of your silhouette start to vanish as well.

I grabbed your image and highlighted the worst shadows.

An image downloaded from the internet is not a great source for keying, but I can use it to show those worst shadows in greater detail. I placed the image in Adobe’s Premier Pro and applied Ultra Key. Switched to Alpha view.

Alpha view shows what’s visible in White.

Masked out features are Pure Black.

Anything that is not masked out. Appears in varying shades of Gray.

Why there isn’t enough lighting falling on the wall? Probably due to how close your actors are to the wall. Or ambient lighting. Lighting you added yourself. Or a combination of all factors.

Lighting is critical, if you could flood the area with natural light “No Direct Sun Light” to avoid shadows altogether. By opening a lot of blinds, curtains, etc. That’s a great way to shoot.

If not, you want plenty of light to hit the wall evenly. And only enough hitting the scene/actors to illuminate Them/It without casting any dark shadows.

 Diffused lighting is best. I use 5500K florescent daylight balanced bulbs. You set the white balance in the camera to Daylight. If the lighting is right “Correct Amount of Light” Color accuracy will usually be spot on. Skin tones, whites, blacks, mid-tones, etc. Color correction is an issue you don’t have to deal with.

2 diffusers are directed primarily on the screen. Positioned at steep angles from the far left side and the far right side of the backdrop.

They put out up to 1500 watts lighting power each. The one in front is identical. It’s usually set to a much lower power than the others.

In this case it was night time. No outside light was coming in at all. The side lights were full blaze 1500 watts. The center was at 900 watts. Each unit holds 5 bulbs activated by their own switch. 300 watts each.

Here’s an alpha version of a keyed out me in Premiere Pro.

And the end result.

Any Green/Blue screen shoot will have it’s own set of challenges. Not all shoots go off without a hitch.

I do my Chroma Key work in Premier Pro or After Effects. Primarily Premiere Pro.

After Effects can salvage footage Premiere Pro cannot.

However, there’s no substitute for quality footage.

 Camtasia has limited keying capability’s. As with “Most” inexpensive editors.

You practically need a studio with studio grade lighting to pull off a “High Quality” key with most inexpensive editors.

 That is if you actually scrutinize scenes for overall quality.

Sure, I could place myself in a green field using cheap software. Nobody would notice the leftover green on my fingers and clothing. Placed in the right background, flaws don’t jump out at you.

That’s the best defense with poor keying, pick a background that hides what you can’t. Stay away from solid colored backgrounds.

Premiere Pro’s Ultra Key is up to the challenge. You can’t hide green remnants on a white background. So I inserted a white background to show Ultra Keys capability’s.

You need more than Tolerance, Softness and Defringe to properly key a background.

If you willing to look past some discrepancy’s. Camtasia does a decent job.

However, if you enlarge the image below and zoom in. That halo of green on my hands and face is pretty thick. It’s unacceptable by my standards. When it comes to video I’m pretty picky. I don’t like sloppy work. Before I starting using this lighting and backdrop. My results would have been considerably worse.   

 Here’s the best I could do with it.

Here’s what Premiere Pros Ultra Keys settings looks like. Just to show what a high end Chroma Key filter settings looks like.

This won’t help with the footage you currently have and I recommend staying away from blue in the future if possible. Just have your actor wear a shirt without green in it.

Unless you plan on using a better grade of editor to key it out.

Or you could try to improve your lighting, reposition the actors and try again. You may get results you can work with.

I’ve been around the block a few times with green screen, this is part of that experience in a nut shell. Hope it helps.    

 Regards, Joe