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Tutorial: Using ROBUSKEY to Create Stellar Keys
Posted Sep 1, 2011 Print Version     Page 1of 1

Grass Valley EDIUS 6 on EventDV.tvThis tutorial is on a new third-party keyer plug-in called ROBUSKEY. What's so great about ROBUSKEY is that it allows you to make a great key out of poorly shot footage. It's a third-party utility that's recently come to market that plugs in really well to EDIUS. I'm going to show you how to clean it up and have your keys looking the best they can be.

Basic Keys with the EDIUS Keyer
First let's look at the EDIUS keyer and see how well it works. I'm starting with a pretty good greenscreen (Figure 1, below). You can probably see there's not a whole lot of issues other than a few spots in the subject's hair where we would have difficulty making a clean key.

Grass Valley EDIUS 6

To begin, let's go to the Effects palette and locate the keyers. Find the chromakey and drop it onto your transparency track. You can see in Figure 2 that with this type of footage, EDIUS' built-in keyer does a pretty good job. There's really no need to venture outside of EDIUS for this type of key.

Grass Valley EDIUS 6

More Challenging Keys
Let's find some more difficult footage. In the section of the EDIUS timeline shown in Figure 3, you can see I've got some more challenging footage. I did a search on the Internet for "challenging green screens" and found a site called HollywoodCameraWork.us, and they had a number of greenscreen keys that were very challenging for one reason or another, and so I grabbed a few of those as examples to show off what ROBUSKEY can do.


To begin, go to Effects > Keyers > Chroma key and drop it on your transparency track. As you can see in Figure 4, EDIUS has keyed out the green pretty well from the screen, and I've got a white background behind it; however, we do have a lot of reflection around the edges picking up the green. The next step is to open up the chroma key and see if you can clean that up just a little bit. In my experimentation I've discovered that the circle gives me a little bit better quality key, so if I drag this up a little bit you can see my greens are getting a little bit more washed out and we're losing those a little bit.


As you can see in Figure 5, by moving the circle around, I've brightened it up and flattened the image somewhat, making it more washed out. But it's also much more usable as well, compared to the bright greens in the original. We still have a little bit of green, but it's pretty well cleaned up and looks much better, for the most part. But in some areas, such as the edges of the subject's hair and some spots on her coat, it's become desaturated. It's not the perfect green screen and it's not the perfect key, but it's fairly usable.


Let's see how close we can get to that "perfect key" with ROBUSKEY. To begin, mute the EDIUS track and open up the ROBUSKEY track. We'll work with the same shot we used in the previous section.

Go back to the beginning of the clip and go to your Effects palette. Note that ROBUSKEY it's not a keyer; it's a greenscreen filter (Figure 6). The fact that ROBUSKEY acts as a filter and not a keyer is huge in EDIUS. Within the EDIUS workflow you're allowed to use only one keyer on the key track, but you can use unlimited filters, so this opens up the opportunity for you to use ROBUSKEY as a filter on your filter track and then still apply other keyers of different types to the keyer track. You get more flexibility this way.


Open the ROBUSKEY information dialog, and you'll see the controls (Figure 7). Let's go through these and study some of them a little bit. Begin by clicking on your eyedropper to select it, then click on something green in your image.


As you can see in Figure 8, we've already got a much cleaner key than what EDIUS was giving us. Scrubbing through, I can see that with the ROBUSKEY filter we're not getting quite the desaturation around her hair that we got with the EDIUS version of the keyer, so this is already a big improvement over what we saw before.


Let's go through some of these controls now and see just exactly what they mean. Up across the top we've got three different options. We can see the result. We can see a matte, where we can help dial in some of our keying to get the fine details worked out, and by clicking on the source, we can see what our original footage looked like. Our next option is Smooth BG, aka smooth background. If we scrub through some of our footage in the example clip, we can see those shadows behind her (Figure 9). That could pose a problem to some keyers. What Smooth BG does is to flatten the background up in the keying process and make it much more consistent, helping us grab a better key.


The next option is Shadow. This will adjust the amount of shadow of objects when the clip being synthesized, so if we start dragging this back and forth we can see some of the results of it. If I go all the way over, it just gets messed up. You can see a little bit of bleed-through on her chin there (Figure 10).


You can see the hair's being affected, so I'm going to have to put it back to 100, back to its default setting. It looked pretty good there. If I come down to the clip black, it adjusts the portion you'd like to move the post-chromakeying alpha channel, so if I start adjusting the black up you can see again her hair is being affected, and there's that chin problem again (Figure 11). If I go all the way over to the edge it just goes white on me. You can also see along the edge of her sleeves that we're losing some of her coat. So I'm going to put that back to the default, zero.


If I start adjusting my white down, it will start to introduce some of those shadows from our greenscreen, the portion behind her that wasn't keyed very well or that was going to affect and give us problems with our key. We're going to ramp that back up to the default settings, because overall those three settings looked pretty good right out of default settings.

The next option down is D-blocking. If I turn that on and I've got footage that has pixel noise or block noise on it, this can help clean it up, and you can adjust the amount of sensitivity. This can come in handy if you're using, say, MPEG footage or HDV footage that could have compression artifacts in it. This could help your keying of those types of files come out much cleaner.

The next option down is the edge contract. If we want to shrink the amount of edge being worked with on our footage, we can adjust our number up and it changes. If you've got a really messy edge this might help it a little bit. You can change the contract threshold and you can ramp that up and it'll just adjust the threshold for how sensitive it is. I'm going to mess with those a little bit, and I still think even right at the default settings of zero and zero for those I still get my best key, so on this particular greenscreen I'm going to turn that option off, but I did want to tell you about what it does.

The next option, Edge Blur, is pretty self-explanatory. This could be handy sometimes if you've got really, really razor-sharp edges on your key that just don't look right. Once it's blurred, you can change the blur value and do some other things that will affect how it looks. Blue removes a bluish reflection in transparent material.

Now, we're almost done with our ROBUSKEY Information palette. We have an area that's advanced for de-spill. The white/gray will remove white spilled to black and gray objects, so if we adjust that and there was a lot of green on there it's going to bring back some noise from the background.

The Skin/Hair Color control removes green spilled into the skin and brown hair. If I adjust this in the example clip, we don't see a whole lot of change unless we drag it all the way down to zero. I'm going to leave that again at the regular setting. If we had a lot of the green bleeding over like we did in the EDIUS version, then this little trick here would've been really good to clean that up. The blue removes green spilled into transparent objects.

Screen Gain, our last option, is used when the color range of the background is too wide to perform a chroma key correctly. If you have GPU acceleration with the right kind of graphics card in your computer, you can get accelerated playback and easier playback if you have that option checked. You can see the final results of what we did in the example clip with ROBUSKEY in Figure 12.


Now let's compare the settings we applied with the ROBUSKEY filter to what EDIUS did. I'm going to turn this channel and turn EDIUS back on. As you can see in Figure 13, we still retained a little bit of that green and we had the washed-out areas in her hair, and if we play that it still played in real time, but you can see it was a really bad, bad key. It just didn't work too well around some of the edges and we've got a lot of green spilling over. In the ROBUSKEY version, you can see that it didn't wash out as much. We still retained a lot of the shadows and the depth in our image. In the EDIUS version you can see the loss of depth; it's much flatter. On this particular type of problem key, the ROBUSKEY does a really good job of cleaning that up.

Grass Valley EDIUS 6

EDIUS has a great keyer when you've got a good greenscreen shot, but when you've got a challenging greenscreen shot, you can see how much of an improvement ROBUSKEY will give you over the EDIUS keyer. So, if you do a lot of greenscreen work, it's important to your business, you may just want to check out this new ROBUSKEY third-party plug-in available for EDIUS.

For more advanced examples of what ROBUSKEY can do, watch the video tutorial that accompanies this article at the top of the page, or check out the 6-part video tutorial series on the EventDV.tv EDIUS 6 page on Vimeo.

Philip Hinkle (philip at frogmanproductions.com) runs Madison, Wis.-area video production company Frogman Productions. A 2008 EventDV 25 honoree and nationally recognized EDIUS instructor, he won a 2008 WEVA CEA Gold in the Social Event category and a 2006 4EVER Group AAA Diamond. He was a 2009 WEVA CEA judge and a featured speaker at WEVA Expo 2009. He is co-founder and vice-president of the Wisconsin Digital Media Group.

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