Latest post Thu, Mar 25 2010 10:54 PM by jwrl. 13 replies.
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  • Sun, Nov 9 2008 3:27 PM

    • unihill
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    Chroma Key

    Does anyone know the best settings for chroma key? I filmed in front of green screen and have a fairly even shade but I can't seem to avoid getting pixelation around the edge of the people's bodies. Does anyone have any tips on ways to avoid this by setting softness, using secondary key, spill supression, etc.

     

    Thanks.

  • Sun, Nov 9 2008 3:41 PM In reply to

    Re: Chroma Key

    What keyer are you using? Best is Spectramatte. A lot of problems can be solved with it. you have to experiment. did you see the free tutorial on ALEX (learning.avid.com)?

    Dell Precision 670, Xeon 3Ghz 3GB Memory 1 x 250 systemdisk, Gb 2x500 Gb datadisks, 4x 1Tb datadisks, Soundblaster Audigy, Quadro FX 1400, MC latest, Mojo... [view my complete system specs]

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  • Tue, Nov 18 2008 7:28 PM In reply to

    • JayT
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    Re: Chroma Key

    SpectraMatte works wonders.  Under the Matte Processing parameter, apply a bit of Matte Blur set to either Blur or Erode.  I've had luck in the past using this on troublesome keys

    MC Adrenaline on HP xw8400 [view my complete system specs]
  • Tue, Nov 18 2008 7:53 PM In reply to

    Re: Chroma Key

    Hi,

    See if this post helps.

    good luck,
    Carl

    Media Composer 2020.6 w/Symphony/SS/PF options, HP Z-Book G6 17", i7-9850H 2.60GHz, 32gb RAM, NVIDIA Quadro RTX 3000, Windows 10 Pro [view my complete system specs]

    "There is hardly anything in the world that some man cannot make a little worse and sell a little cheaper, and the people who only consider the price are this man's lawful prey."  - John Ruskin (1819-1900)

     

    Carl Amoscato | Freelance Film & Video Editor | London, UK

  • Thu, Mar 25 2010 12:15 PM In reply to

    • Sagerman
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    Re: Chroma Key

    Let me admit right off the bat, I'm no filming or film editor expert. If anything I'm a novice and question if I rank even that high. Just the same, can someone tell me why such a high end product like Media Composer 4 can't have a chroma keyer that functions without making you fight it?

    I have but no longer use Pinnacle Studio 11 and found the keyer fast and VERY often without the green fuzz around the subject that vexes so many of us. I mean the keyer just did it's job and I had a clean key, very rarely did I have to tweak anything. The only reason I don't use the software is Pinnacle Studio still has a nasty habit of crashing right in the middle of a job, over and over. I have Ulead Studio, Ultra 2, and Sony Vegas Pro 9 and none of them go kamizee on me. But I have to admit the PS keyer worked with ridiculous ease. MC being so high end and expensive should run rings around such lower ended products and it does except with the PS chroma keying. The question is why? The other question is will this change anytime soon?

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  • Thu, Mar 25 2010 12:32 PM In reply to

    Re: Chroma Key

    Hi,

    It seems that your question could be paraphrased as "Why does the chroma keyer suck?" and I don't know how to answer that.  What are you shooting on?  What resolution are you capturing?  Do you have a DOP there properly lighting the background?  Have you tried SpectraMatte keyer?

    Generally speaking, the format shot, the lighting on set and the resolution you're using to capture have a lot to do with how successful your key will be.  An HDCAM shoot with a DOP who knows what they're doing, and capturing the footage at 1:1 will be a lot better situation than a consumer miniDV shoot with no DOP captured at DV25.

    Tell us what your workflow is and we might be able to help.

    ciao,
    Carl 

    Media Composer 2020.6 w/Symphony/SS/PF options, HP Z-Book G6 17", i7-9850H 2.60GHz, 32gb RAM, NVIDIA Quadro RTX 3000, Windows 10 Pro [view my complete system specs]

    "There is hardly anything in the world that some man cannot make a little worse and sell a little cheaper, and the people who only consider the price are this man's lawful prey."  - John Ruskin (1819-1900)

     

    Carl Amoscato | Freelance Film & Video Editor | London, UK

  • Thu, Mar 25 2010 1:30 PM In reply to

    • Sagerman
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    Re: Chroma Key

    Well, let's not say the keyer sucks. It just seems to require you to do a lot of work compared to the Pinnacle Studio keyer. With PS, keying was fast and simple and usually without a need to tweak anything. You can't have that privilege every time but it was amazing how often that's what you got. But with MC, it's more of an ordeal.

     

    Ok, now about your questions, i iwll try best as I know how to answer them.  I'm not expert as I said.

    Shooting: Green and Blue screens. usually in natural light during morning hours before the sun is in position to cast shadows. I use large green or blue backdrops made of fabric bought from a fabric store and secured very tautly with tacks. except on very windy days, the fabric is utterly motionless. camera used is a Panasonic HDC- TM300

    capture Resolution: Ranges from SD to HD, I've pretty much tried every resolution and format in search of clean keys and selections the previously mentioned softwares compatibilities.

    DOP? My ignorance shows. Don't know what DOP is but do know I tend touse natural lighting. The times I shoot indoors, it's with bright flourescent lights. Once in a while I use two 250 lumens LED spot lights to remove shadows.

    Footage at 1:1, frankly I haven't even thought of that or knew about it until now. So I guess the new question for me is whether software can capture at 1:1. I'm sure MC 4 can and probably Vegas 9 Pro too so will give that a look see soon.

    Asus G75VW-RS72: Ram = 24GB DDR3 HD = (2)750GB (7200RPM) GPU = nVIDIA GeForce GTX 670M (3GB GDDR5 VRAM) OS = Windows 7 X64 Ultimate CPU = Intel Mobile... [view my complete system specs]
  • Thu, Mar 25 2010 2:23 PM In reply to

    Re: Chroma Key

    Hi,

    A couple of things to think about.

    Sagerman:
    I use large green or blue backdrops made of fabric bought from a fabric store...

    Are they specifically chroma blue or chroma green?  I ask because there are specific colors that the default Chroma Key settings are designed to work with.  If the colors you're using are not the same as what Media Composer is expecting, you might have to tweak the effect a bit to get it to work.

    Sagerman:
    camera used is a Panasonic HDC- TM300

    Not to denigrate your camera, but it's got a pretty small lens, pretty small imaging chips, and its highest resolution is 1080x1920 AVCHD at 17 Mbps.  That's good, but it's not a professional camera in a studio under controlled lighting designed for chroma keying by a director of photography (DOP) who has spent their whole professional life working out how to chroma key effectively.

    Sagerman:
    Footage at 1:1, frankly I haven't even thought of that or knew about it until now. So I guess the new question for me is whether software can capture at 1:1. I'm sure MC 4 can and probably Vegas 9 Pro too so will give that a look see soon.

    For MC it depends on how you're getting the footage into the system and what hardware you've got available.  If you can capture (or import AVCHD files) at 1:1 that's a better starting point for chroma keying than DV25.

    As for why Pinnacle Studio worked so well, I have no idea.  Maybe because it's aimed at prosumers it does a lot of the tweaking work for you, whereas MC is aimed at people who are happy to tweak a bit because they want more control over the image.  That's just a guess; I've never used Studio, so I don't know.

    Anyway, I hope something in there helps you or at least gets you on the path to an easier time chroma keying.

    ciao,
    Carl 

    Media Composer 2020.6 w/Symphony/SS/PF options, HP Z-Book G6 17", i7-9850H 2.60GHz, 32gb RAM, NVIDIA Quadro RTX 3000, Windows 10 Pro [view my complete system specs]

    "There is hardly anything in the world that some man cannot make a little worse and sell a little cheaper, and the people who only consider the price are this man's lawful prey."  - John Ruskin (1819-1900)

     

    Carl Amoscato | Freelance Film & Video Editor | London, UK

  • Thu, Mar 25 2010 3:41 PM In reply to

    • Sagerman
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    Re: Chroma Key

    Hi,

    A couple of things to think about.

    Sagerman: I use large green or blue backdrops made of fabric bought from a fabric store...

    Are they specifically chroma blue or chroma green?  I ask because there are specific colors that the default Chroma Key settings are designed to work with.  If the colors you're using are not the same as what Media Composer is expecting, you might have to tweak the effect a bit to get it to work.

     

    Probably not because what I did was print out greens and blues form my software then eye matched the fabrics I bought. Let me stress the PS has no problem with my backdrops and Ultra 2, Sony Vegas Pro 9, and even Ulead Studio 11has no problem with them.

    Sagerman: camera used is a Panasonic HDC- TM300

    Not to denigrate your camera, but it's got a pretty small lens, pretty small imaging chips, and its highest resolution is 1080x1920 AVCHD at 17 Mbps.  That's good, but it's not a professional camera in a studio under controlled lighting designed for chroma keying by a director of photography (DOP) who has spent their whole professional life working out how to chroma key effectively.

     

    No offense taken, it's not a professional camera, just all I could afford for now. I'm not into major film making, I simply want to make decent quality video for making instruction media for sign language students. i bought MC4 because I figured I'd be able to get pretty decent output for simple things like placing a subject into a themed background, hence my chroma key issue. All without the frustrations of crashes like PS 11, or the inconsistent output I frequently experience with other software. inconsistent meaning on some days I get crystal clear footage and others the subject is fuzzy. I thought MC would put an end to the need to switch between editor software to get certain results.

    Sagerman: Footage at 1:1, frankly I haven't even thought of that or knew about it until now. So I guess the new question for me is whether software can capture at 1:1. I'm sure MC 4 can and probably Vegas 9 Pro too so will give that a look see soon.

    For MC it depends on how you're getting the footage into the system and what hardware you've got available.  If you can capture (or import AVCHD files) at 1:1 that's a better starting point for chroma keying than DV25.

     

    I didn't pay specific attention to this before but will now. i use a SDHC card reader to input my AVCHD video.

     

    As for why Pinnacle Studio worked so well, I have no idea.  Maybe because it's aimed at prosumers it does a lot of the tweaking work for you, whereas MC is aimed at people who are happy to tweak a bit because they want more control over the image.  That's just a guess; I've never used Studio, so I don't know.

     

    What you say makes sense but I'd expect a high end editor like MC4 to not require so much effort unless someone wanted to tweak beyond what woudl be at least ana cceptable key result.

    Anyway, I hope something in there helps you or at least gets you on the path to an easier time chroma keying.

     

    I think I'll get there eventually. I'm flirting with taking a MC4 class either at a local university or online.

    Asus G75VW-RS72: Ram = 24GB DDR3 HD = (2)750GB (7200RPM) GPU = nVIDIA GeForce GTX 670M (3GB GDDR5 VRAM) OS = Windows 7 X64 Ultimate CPU = Intel Mobile... [view my complete system specs]
  • Thu, Mar 25 2010 3:52 PM In reply to

    Re: Chroma Key

    Hi,

    Sagerman:
    I'm flirting with taking a MC4 class either at a local university or online.

    I took the Advanced Effects class a few years ago, and they spend a lot of time on chroma keying.  Might be worth it for what you're trying to do.

    ciao,
    Carl 

    Media Composer 2020.6 w/Symphony/SS/PF options, HP Z-Book G6 17", i7-9850H 2.60GHz, 32gb RAM, NVIDIA Quadro RTX 3000, Windows 10 Pro [view my complete system specs]

    "There is hardly anything in the world that some man cannot make a little worse and sell a little cheaper, and the people who only consider the price are this man's lawful prey."  - John Ruskin (1819-1900)

     

    Carl Amoscato | Freelance Film & Video Editor | London, UK

  • Thu, Mar 25 2010 4:16 PM In reply to

    • ducktech2
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    Re: Chroma Key

    I have to say, having done green screen shoots for a number of years, I completely agree that the chroma material, camera and lighting play the biggest part in how good of key you end up with.  However, saying that, I also agree with Sagerman in my amazement on how much better 3rd party keyers are than the Avid's.  Sure you can spend hours tweaking your key to get it just right, but shouldn't we be able to pick a few quick samples of green and be done?  I had almost the exact same senerio as Sagerman last year.  Green screen footage came from the offline edit, where the editors used the Avid keyer, to my Symphony.  It was shot fantastically and onlined at 1:1, but the key from Avid looked terrible with a halo around the subject.  I removed the Avid key and dropped on Ultimatte.  Used the picker for one color sample right on the person's edge and POOF!!  I had to do nothing else.  Absolute perfect key.  All my hours were simply spent removing the hideous key from Avid and replacing it with Ultimatte.

    The bottom line is that the technology exists to do easy, nearly one step keying, it just doesn't seem to exist in MC software.

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  • Thu, Mar 25 2010 4:56 PM In reply to

    • Sagerman
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    Re: Chroma Key

    ducktech2, you understand me perfectly. It's the time spent getting a decent key out of MC4 that irks me.

    Then you look at the ridiculous ease that a "kiddie" editor like Pinnacle Studio gives you clean key and it doesn't

    make sense for Avid to be essentially inferior in terms of a quick and simple keying function. Especially with the software costing what MC4 does compared to some little $99 editor.

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  • Thu, Mar 25 2010 7:00 PM In reply to

    • Jayanta
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    Re: Chroma Key

    Sagerman:
    Are they specifically chroma blue or chroma green?  

    Yes there is

    For Blue Screen The Value of RGB are as follows

    R = 0  G= 0 B = 242

    For Green Screen

    R = 0 G = 242 B = 0

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  • Thu, Mar 25 2010 10:54 PM In reply to

    • jwrl
    • Top 25 Contributor
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    Re: Chroma Key

    Sagerman:
    ducktech2, you understand me perfectly. It's the time spent getting a decent key out of MC4 that irks me
    Possibly the problem is one of expectations.

    Prior to Spectramatte I used to use third party keyers because there weren't enough parameters for me to adjust in either Avid's RGB keyer or chroma keyer.  Those were OK for quick-and-dirty work, but for anything requiring a little precision, forget it!  If I had to use those keyers I often used multiple layers of combinations of luma and chroma keys.

    Don't get me wrong; the RGB keyer will usually give adequate results very quickly.  But for sophisticated keying you need a sophisticated keyer.  That sophistication brings with it lots of options, any or all of which may require adjustment.

    I need matte softening, erosion, secondary keying, spill suppression and all the other goodies that Spectramatte brings.  If I didn't have them I'd be doing my keying in After Effects.  And if you think that Avid's keyers are tough, some of those in AE are absolute doozies!

    It might be argued that the defaults in Spectramatte could be better selected to give simpler set-and-forget keying.  Obviously for your purposes Ultimatte's defaults are better.  But Ultimatte is hardly a simple keyer.  When you come to fine tuning your key Ultimatte can be every bit as complex to adjust as Spectramatte.

    My point at the end of this lengthy post is this.  My expectation of a keyer is that it will require a fair degree of adjustment to get exactly the right result.  Your expectation is for a quick fix solution.  They are different needs.

    MC 7.0.4 - Asus P6T Deluxe V2 mobo - Intel i7 920 2.66GHz - Windows 7 Ult64 SP1 - nVidia Quadro FX 1800 - 16 Gbyte low latency DDR3 RAM - Internal 8 Tb... [view my complete system specs]
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