I'm struggling a bit with chroma-key. Can you help?
 

Hey gang. I've been trying to get my chroma-keys perfect and it's wearing me down. I can get a good seperation with either blue OR green screen. I can even get a sharp, detailed edge between my subjects and the key.

The problem is that it seems like I have a choice of having a bit of transparency to my subject. (Too much to be acceptable) or else rediculous jaggies surrounding them if they aren't transparent at all.

The transparency allows too much of the overlay detail to come through their body. It's crap.

I've set up a chroma wall with seamless paper and it's evenly lit with Kino tubes in homemade fixtures... I've also played with the light levels on the subject and it's definitely been a bee-otch since I haven't figured it out yet.

My system is a Canopus RT system that's supposed to be particularly good at this... so I'm just wondering how I get my subject CRISP with ZERO transparency and a clean edge of seperation between him/her and the key?

I even tried the magenta gel and backlight... what do you think I'm doing wrong?

This procedure will work with any video editing app that has layers (I use Adobe Premiere 6.5, but I don't see why this technique wouldn't work with any editing app). This info applies specifically for Adobe Premiere 6.5, however.

Lets face it: Premiere's chroma-keying sucks, but I've found a way to get very professional looking composits using only Premiere with no additional plugins or other software:

1. Shoot your green-screen footage. It's good to have a well lit green-screen, but even lighting is more important then brightness (You'll see why in a minute).

2. Capture your footage. Once you bring it into your editing app, load your footage on the first overlay track (layer 2 for Premiere)

3. Apply the filters to adjust the saturation levels of this video clip to 200% or better, especially for the green. This will really bring out the green background. Sorry, can't remeber the exact name of the filter, I'm not in front of Premiere right now, I'm doing this from memory...

4. In the transparency settings, choose Chroma-Key from the drop down and use the eye-dropper to sample the green background, then choose "Mask Only" on the right side of the dialog. Close the Transparency window.

5. Sometimes, you will have to clean up parts of this mask, so if you need to do this, simply create a title and apply white or black shapes to the imperfections to get rid of any trouble spots. You may have to keyframe some of these things so you might have to create multiple titles, it just depends on how "clean" your green screen footage is.

5a. At this point, you can either create a virtual clip or render out this video into another clip. I usually just render this out because my wife says I can't feed both my video jones AND my computer jones (I have a slow PC). We'll be using this clip to create a "cookie-cutter" for our composited final video

6. Make a new project, load your clips, including the mask you just created, and put your plate footage (thats the background footage on which you will lay everything) on the first track (1a for Premiere)

7. Put the mask you just created on track 2 and change the transparency settings for this clip to "track matte".

8. Place your original greenscreen clip On track 3. Change the Hue so the clip is relatively close to the same color as your plate footage. This goes a long way towards eliminating a white or black line around your composited image. You can also play around with the opacity settings. Change the transparency to track matte.

9. Put your original greenscreen clip on track 4, and change the opacity of this clip to around 70%. You may have to adjust the saturation to add a little color back into to image. Again, change the transparency to track matte.

10. Render your image (go get a beer and come back later).

Sounds like a lot of work, but the results are worth it. No more fuzzy edges. No more green or blue tinted composits. Crisp, clear images. Who needs Ultimatte!

Cheers,
slakrboy

Thanks Mark. That does sound like a lot of work, but I'll try it... I'm just across the river in STL by the way.

Also your advice should suit me well since I'm also in Premiere. Thanks.

Glad to be of service. BTW, I get just as good results with this technique as I do with AE 5.5, and it's actually not that hard once you do it a few times. You can use this technique with any solid colored background, but you'll have to clean the matte up a little (or use multiple mattes). I do lots of sports video's, and I can usually pull a decent matte out of most footage.

Cheers,
Mark

We had been getting good chroma keys using Ultimatte, but recently we started playing around with the keying in Boris, and in most cases it gives us perfect keys, better than Ultimatte.

UltraKey which is a new product I use from Serious Magic also creates excellent keys in the worst conditions and lighting. It also includes a lot of virtual sets. (seriousmagic.com)

Thanks Jim. I keep seeing their adds in all the video magazines and it makes me wonder if it really works that well. I also read the DV article on chroma a while back and have employed their techniques.

I think my main problem has been that my subject is too close to the screen and the green spill is getting on them. I took the advice of my local Kino salesman and bought green tubes to light the background and that makes the green bounce really far back off the screen. Using white lights improved the matte on close range and I'm going to rearrange my screen today so I can get my subject over 10' from it... then I'll report back.

I already have a Canopus RaptorRT (about 1 year old) which is supposed to be exceptional at green screen... so I'll continue to experiment before I give up on it and try seriousmagic.

Bill, are you "BillKC"?

Anybody else notice that somebody else started the exact same thread a couple days after mine? I'll take the combination of answers from both and hopefully he will too.

Anyone have any new blue/green screen experiences?
 

I've asked this befor but I am anxious to hear of anyones experience.
Any problems with chroma noise? Any colour backing you find works better or worse than another?
Any particular lighting or filters that help?
Thanx Ken

DV25 isn't the best format for green screening but with a little work you can get some decent results.

1. make sure your green screen is eveningly illuminated.
2. keep your subject a good distance from the screen

Most prosumer NLE's have chromakeying capabilities so that shouldn't be an issue. Also, do some searches, there are a lot more tips out there then I gave you.

Ken is asking about the chroma keying in regards to these JVC HD cams, I understand.

Of course, general green screen suggestions apply as always.

In short, my experience with HD10's green/blue screen is exactly what I expected: it sucks.

JVC HD cams' chroma noise is crazy on all same-color surfaces, which by definition includes green/blue screen areas.

Quality 3 CCD miniDV camcorder produces *much* better results with keying because of the lower chroma noise.

If someone has a different experience with JVC HD cams and keying, then tell us how do you fight the chroma noise and I'll be happy to stand corrected.

DV can be as good as betaSP for chroma keying if using the right tools. Some NLEs aren't that good at chroma keying (premiere 6.x for example).

From Adam Wilt's DV FAQ:

Can I chroma-key with 4:1:1 / 4:2:0?
Yes indeed. Many early DVEs were 4:1:1 internally; plenty of digital boxes out there still are (such as the Panasonic WJ-MX50 and Sony FXE-series vision mixers, both of which chroma-key). As previously mentioned, BetaSP could be considered a 3:1:1 format in terms of component bandwidth, and BetaSP is used for chroma-key applications all the time. With some care, DV25 keys at least as well as BetaSP; read on...
Part of the standard JVC sales pitch for D-9 is the superiority of 4:2:2 (which is true), and the utter doom and degradation that awaits you should you try to do anything -- including chroma-key -- with a 4:1:1 format (which is, shall we say, a wee bit exaggerated). But that doesn't mean that you can't do very satisfactory work in 4:1:1.

JVC has an excellent D-9 demo tape showing multigeneration performance comparisons of DV, D-9, and Digital Betacam; watch it if you can. Just be sure you take the hype with a grain of salt.

True, the chroma performance of 4:2:2 formats is superior to 4:1:1 formats, especially in multigeneration analog dubbing. But by the same token, 4:4:4 is as superior to 4:2:2 as 4:2:2 is to 4:1:1 or 4:2:0.

Where DV can get into trouble is that the coarse resolution of the chroma signal (only 180 samples per scanline in 4:1:1) leads to a very regular, "steppy" key signal, most noticeable on near-vertical edges or vertical edges where motion is present, especially if the codec's decompression simply replicates the chroma sample across the intervening pixels instead of low-pass filtering or interpolating between samples. The 4:2:0 sampling in 625 DV/DVCAM is somewhat better in this regard, but it has its own problems vertically, so there's always a tradeoff.


The single most important factor in good DV chroma-keying is low-pass filtering or interpolating the chroma prior to applying the keyer, so that the “steppy edges” are knocked off. Some codecs do a pretty good job of this by default (Avid DV); some can be set up for it (Matrox: Control Panel > Sounds and Multimedia > Hardware > Video Codecs > Properties > Matrox VFW Software Codecs > Settings... > Chroma Interpolation (YUV -> RGB)); with others you can add a filter (I have filters for FCP here). Some people capture DV for chroma keying using an analog Y/C feed, since the analog connection prefilters and smooths the chroma. The Matrox RTX.100 DV NLE board uses multi-tap resampling of DV's chroma to generate astoundingly good, crisp, finely-detailed keys in real time – so there is certainly enough information on DV's chroma for most keying purposes; the only tricky bit is recovering it intelligently!


Additionally, use the matte choker and/or matte feathering and smoothing controls of your keyer to round off the edges a hard-cut key signal gives you. I've had excellent results with After Effects Production Bundle's Color Difference key, and superb results also using the Chroma Keyer in Final Cut Pro 3. Using these tools I can make very clean and acceptable keys, certainly for hard-edged keying. Spill supressors (or “edge enhance” in FCP 3's Chroma Keyer) are essential in cleaning up any remaining chroma spill in the foreground video.

You may also find that layering different key signals gives you excellent results. I've used a heavily-choked chroma key to cut my main matte, but then add one or two luma, extract, or difference keys to define the edge detail that the chroma key can't get. Each luma key may only work for a small part of the image; it may lose the greenscreen background but also lose the interior of a similarly-bright face. However, it usually is able to get edge detail, because the edges of a person fall off in shadow or are picked out brightly by the rimlight, and the chroma key holds the interior matte that the luma key won't provide.

John Jackman has some good examples on his post-production pages at greatdv.com.

green screen
 

Hello,

i recently shot some green screen footage with the DVX100. Considering my limited knowledge in lighting, it turned out ok.
Though my only concern in how to eliminate the green bleed that appeared around the edges of the subject, i could also use some advice for the backdrop lighting of the screen itself.

any thoughts would be appreciated.

Thanks

Depends a lot on which software you are using. Normally you
feather the edge of the mask (ie, you blur the edge) so that the
foreground will blend into the background. Some blue/green
screen software has specific functions to remove spill.

Most people advice to have the actors / objects futher away
from the screen to remove spill. But if you have already shot
the footage this is not possible, ofcourse.

Which NLE or keying program are you using? Some of them don't apply chroma interpolation/smoothing unless you get certain filters or tell it to. That will improve your results.

Also note that the DVX has a pulsing chroma problem on pans. Check out Adam Wilt's website for info on that.
http://www.adamwilt.com/24p/index.html
The DV FAQ on his site gives great information on other things like getting keys from DV (talks about the chroma interpolation thing I mentioned).

these were stationary shots. I am using After Effects chroma key.
I tried even using Combustion, not much better. The down fall of the bleeds is that the edges tend to get a bit "crawly" softening them jsut makes it smudgy after keying out the green....I noticed the backdrop wasnt as smooth lighted as it could of been..

anyone have any tips on the backdrop lighting??

If you are in AE, you want to use Spill Supression.

If you want a really good article on keying in AE, check out my website. I have a tutorial on how to create the StarWars Hologram effect.

Cheers

Adam,

Your background should be evenly lit, no hot-spots or drop-offs, and slightly "hotter" than your foreground subject. Separation, distance wise, from the BG is also important in that it will help reduce any contamination from the green caused by reflection.

Another way of combating the contamination problem is to use a soft rim or backlight light with an amber or straw gel.

Adam,

Your background should be evenly lit, no hot-spots or drop-offs, and slightly "hotter" than your foreground subject. Separation, distance wise, from the BG is also important in that it will help reduce any contamination from the green caused by reflection.

Another way of combating the contamination problem is to use a soft rim or backlight light with an amber or straw gel.

RB.

Since you've already shot the footage, it sounds like your best bet will be to use a garbage matte over smaller portions of the image, that way you get better control of the key. I do lots of "home" greenscreen, and I have yet to get an evenly lit background. I always have to break the image into smaller pieces to get a good key, usually anywhere from 9-16 layers! Takes a while, but you can get decent results that way. for an example, check this out:

www.jeffersons.org/bball.wmv

In some cases, I have 16 layers. The greenscreen looked as evenly lit as I could get it, but the interview outtakes at the end show just how un-evenly lit the image was. Keep in mind that the lighting looked completely flat when I shot the interviews.

Cheers,
Mark Jefferson

Mark,

on the field monitor, the screen looked evenly lit as well, untill ofcourse i brought the footage into AE. I ended up using color range, spill suppressor, and some additional layered masks. the footage came out decent. Thanks for the help guys, ill post a link when im finished.

-Adam

What I found that worked very well was to light chromagreen fabric from the backside. Only had a double trailer classroom in which to work. Not even 8 foot ceilings.

Put a DP light on a stand centered about 12 foot in back of the screen. Centered the person in front of the green and hiding the hot spot caused by the light.

Used a Garbage matt on the extreme edges. Only problem was I couldn't get the person far enough away from the green to prevent some spill. Should have used some orange rim lights as he was wearing a SWAT uniform of very dark blue. Still the spill suppression worked OK. Did this in AE Pro.

I visited the local CBS affiliate in San Francisco. Their weather station was painted in the Chroma color paint from Ultramatte. And the keying was done by an Ultramatte hardware keyer. Very bright lights, very dirty green paint caused by the weatherpersons rubbing up against it. If you looked very closely, the keying wasn't perfect. But other than no wrinkles, they somehow violated all the 'don't doo's' in the book.

Chroma Key Question
 

I would like to begin doing chroma keying and have been impressed by Serious Magic's Ultra.

1. I'm wondering if any readers of this thread have used the product and how it compares to simply buying the standard green 5x7 from B+H and using my Premiere Pro green-key effect.

2. Are the improvements to the chroma-key software worth the $800 price-tag of Ultra?

3. Do any of you use Visual Communicator instead - - - I've heard that you can do workarounds with Communicator in order to use the output in larger projects?

4. Is 5x7 good enough for most applications or should pay a few more bucks and get an 8x16 collapsable?

Any advise is welcome.

I can only answer your 4th question--the 5X7' screen will not be big enough for anything but fairly tight head and shoulder shots. One problem with shooting chroma key is that you need to keep the talent as far away from the screen as possible to avoid green reflection. This is more important if someone is blonde or if they're wearing shiny clothes. It's amazing how much green a dark blue synthetic fabric blazer will pick up. I keep everybody about 7-10 feet from the screen and get good quality keying that way. An 8'X16' screen would be good enough for most things I do. In fact, that's about the size of the wall I use.
We used Ultimatte for most of our keying till recently, when I discovered that our new Boris upgrade was giving better quality keys with less hassle; so we use Boris about 90% of the time now. There are still some situations in which Ultimatte seems to work better. I'm not familiar with any of the software you mentioned. The main contributor to good keying is lighting. We shoot all DVCAM now and get the same quality keying we did with Betacam SP, but I do have to be equally, if not more, precise with the lighting. When I was digitizing into an Avid Media Composer via component out of the DVCAM deck, the keying was easier than it is now that I'm capturing via firewire. We can still get excellent keys, but you can't cut any corners in lighting.

1) premiere is no match for Ultra key. huge difference between the 2. many NLE's come with a chroma key FX but few create clean keys... don't know if there is a difference between ultra's 5x7 green VS B&H ? but guessing use any chroma green/blue.

2) if you do green/blue screen on a regular basis shooting DV IMO it is worth 800 - it is very fast. i use commotion or combustion with primatte keyer. for DV i have to work at getting clean keys .. guessing- what it takes me 10 min to do in commotion takes about 1-2 min in Ultra.
i have to admit that using their 5x7 ( thats what was there) behind (2 ft) a person ( shot head to toe) using just ambient light that was at DV expo clean keys were produced in less then a minute ( that included cleaning the full frame - the 5X7 did not fill the frame) ...
also the green screen they set up for their presentation was uneven lit ( very spotty lighting) and again Ultra had clean keys in less then a minute.

i don't shoot much green/blue screen so for time being i'll stick with commotion and combustion but if something with alot of green/blue screen came up i'd take a look at the cost effectiveness of Ultra

I own Visual Communicator and Ultra.

1. 5 x 7 size is too small for full body shots. I use 10 x 15 at a minimum but it depends on what you're shooting.

2. Ultra does an excellent job keying. I've beat it up pretty good and compared against Vegas and there is no comparison. Ultra is flexible and does a good job.

3. Visual Communicator is a totally different animal. It's interesting and unique in it's own way but more for teleprompter type interview (head shots). But not limited to just that.

In VC you are usually keying live shots where Ultra uses clips recorded from the camera rendered to use in your NLE. You could use clips created with Ultra in Visual communicator. Ultra is superior to VC in keying. Ultra has some pretty nice virtual sets and VC has great audio clips, graphics and title editors. It's all very addicting.

4. The collapsable screen is handy but I like to lay out the excess cloth on the floor to walk on for the interesting full body shots that Ultra can create.

And one thing more to mention is Serious Magic's customer support is superior to any software package you'll find ANYWHERE. Plus Ultra is pretty forgiving with bad lighting or wrinkles in your material unlike other keying software/hardware.

Look at this example I created with an animation product I was playing with and Ultra. Notice the reflection on the floor that Ultra did. Substitute the rabbit for your talent and you'll see their reflection.
http://www.magoomedia.com/media/rabbit.wmv

You might want to take a look at the upcomming ( about 1 week overdue ) Chromanator from fxhome.com . It seems that for about $89.00 this will provide you with a very cost effective tool for your chromakeying.

Blue Screen, Green Screen.
 

What is the difference between the 2? Why is a green screen used some times and blue screen other times? Is there a difference?

Bluescreen or Greenscreen selection information.
Have fun.

Green screen is used more often, it seems, because some twerp always shows up wearing some item of clothing that's blue. When you chroma key something, the background has to be a different color from anything on the subject. Some people claim that one color keys better than another, but I haven't been able to tell any difference recently, although a few years ago when I was using an early model Media Composer, it's Avid keying software seemed to like blue better. Now we still use Avids but use Ultimatte and Boris for keying, and they don't seem to care what the color is as long as it's different.

It basically depends on the colors you put in front of the screen.
Green is the most forgiving in this case since blue happens more
in clothing indeed.

But I've also seen orange screens (Star Trek with model shooting)
and some other colors.

Green is better if you are trying to key in the DV realm as it is the least compressed of the three channels.

I wrote about "Going Green" in one of my articles some months ago (found on my website)

However, in today's digital world, you can create a key on nearly any background providing that the key background color does not show up in the foreground subject. In a pinch I once keyed off a purple background. It was a pretty tough key to pull, but it can be done.

In my "kit" I have both blue and green screens depending on the situation. Two of my screens - one a Westscott Scrim Jim, and the other a Photoflex collapsable - are reversable making them the two most used backdrops.

Of course in addition to selecting the right color, lighting plays an important role in making sure you get a perfect key... I just happen to have a rather lengthy tutorial on how to recreate a Star Wars hologram effect in my After Effects section of my website (Hologram 6.0), that also talks about setting up and lighting for green and blue screen. In the tutorial I use blue with DV and am able to pull off a great effect.


Cheers

Green Screen Pantone?
 

Hello there,

I have to shoot some stuff with green screen on dv. Yes, I know, the DV's colour sampling isn't the best for this kind of job, but I shot a test last year and after quite a lot of work in post production I was satified with the results.
Now, I'm hiring a studio. They gonna paint a wall completely green to let me do some shots. They asked me for the pantone colour. Any idea? On internet I've read somewhere that the pantone 354 is the right one.
Unfortunately I have troubles with colours (I'm kind of colour blind, not bad for this job, uh?), and I can't check it visually.
Any help appreciated :)

Tell them to buy chroma key green paint from a studio supply house.
www.studiodepot.com
www.markertek.com

Green Screen ala' Chuck E Cheese?
 

I was at a Chuck E Cheese with my kids and they had a setup with a camera, a monitor, and a green screen. When the kids stood in front of the green screen, they showed up on the monitor with various backgrounds.

The green screen was actually some sort of translucent plastic that was lit up evenly from behind somehow, rather than a typical green surface lit from the front. On the monitor the results looked pretty good.

I haven't seen this discussed here (but I may have missed it). Has anyone tried this approach? How would you go about making something like that?

Can you go back in there and just take another look. I'm sure if you ask the manager and explain what you do and why you're interested they'll let you back there to take a look. If it's not enclosed you should be able to do it without asking. I'm interested to know how that's done lit from the rear as well. Thanks.

I'll have to do that. I'm not sure the Manager will have a clue, but maybe he/she will at least let me try to figure out what they are doing. At first glance it looked like a self-contained unit so I may not be able to see the guts.

if he doesn't know, and even if you get an answer, check the lens on the front of the camera for any special attachment it may have

Alturo, would you happen to be talking about that circular array that mounts around the lens that produces virtual backgrounds?

After effects-chroma keyers
 

My Dv footage is in 4:1:1 so when I green screen I get blocky edges, I found a solution on this page. (the Photoshop/Premiere method)
http://www.neopics.com/bluescreen/
However when I save the .flm file from photoshop it saves it huge (1.3 gigs for a 30-40 sec) Plus its so slow. Is there any plugins for After Effects 6.5 or Premiere that would fix this? Thanks

I'm a big fan of DVMatte Pro. It does something similar I believe, in AE without having to export gigantic filmstrips.

http://www.dvgarage.com/prod/prod.php?prod=dvmatteae