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Chroma Key is Coloring my Video
I’m doing some Chroma Keying in Vegas and I’m having no luck, and I can’t help but notice what seems to be VERY unacceptable results and either really bad design, a bug, or I don’t know what I’m doing :O)
I am shooting on a green screen. I am applying a Chroma blur first, and selecting a range w/ the eye dropper, and my key is fine, but it seems Sony somehow tries to compensate the for my green key by adding a purple tint to the edges and things that are not keyed out. In one scene someone is dressed in blue jeans and a denim shirt and it totally changes the color of his clothes to purple once I apply the chromakey.
I’m not sure why this is happening, but I can’t image this is normal or by design. On my first scence I just noticed some purple around the edges of the key, I added another chroma key to remove the purple around the edges and it’s OK. But now on the next scene it’s changing my actors clothes to purple!
I know someone might say – “Go out and buy Serious Magic Ultra, it rox” , but it costs more or almost that of Vegas, and I’m doing this for free for a church and not in a studio or have the budget to buy Ultra for personal use. So I was hoping to get this done w/ Vegas. Do I have a setting wrong or something,
This is hard to explain, but On most keying programs, when you sample the color to be pulled it keys it out, and you have to tweak it to pull the remaining key, some color may be bright or darker ect. What I am seeing is after I select the first color, it turns all the surrounding similar colors purple. This is wierd to me.
Is this normal behavior or does anyone else notice purple when they key green?
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9 Replies
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If you adjust the sliders in the chromakey window, you should be able to get good results. Look at a chromakey thread just a little way down this post index for some ideas and a great tutorial link on chromakeying.
Mary Waitrovich
UW-Madison -
I do alot of keying in Vegas. I spent the time on lighting, and settings in vegas. We are able to get very acceptable results….only when its’ done right though.
I am not experiencing what you have going on.
Seems as though there might be a filter or effect somewhere else in you video chain that is being affected by this.Do you have a third party video card for output?
Is it happening in the preview window and on external monitor.
Is your track composting mode set to “source alpha” ?
Maybe have to do a Vegas default settings re-set and try again.Seems like you get the concept and I bet there is a simple solution to this behaviour.
I too am resisting getting “Ultra key 2”Zipedit
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Too me it looks like Vegas Chroma Key automatically applies a spill surpressor to the key. From using spill surpressor in programs like After Effects, I’ve noticed it can do some funky things w/ the color and tint of colors. Looks like it is using magenta tones to balance out the green from the key.
The problem w/ this is you have no control over it and cannot disable it that I can see, so in my scene where I have a man walk on screen w/ blue jeans and a denim shirt, it makes his blue jeans and shirt magenta.
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Understood !
However.. I don’t, haven’t run into that at all.
? How much of the pants change.
just the very edge or the whole thing ?
Does it look like a spill issue or a full color shift on the shirt or pants.
Try a opposite color shirt, see what happens. a Magenta shirt ?
I’m very curious on how this is happpening to you.I have a fill light that has an Amber gel on it that is back by the blue screen and points at the subject. This creates a amber edge along the subject that counteracts the blue spill from the screen.
How close is your subject to the screen ?Zipedit
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I’ll post some screen shots later tonight when I get home.
On the shirt and pants, it’s a total color shift not just the edge.
I wish I had the resources for that extensive lighting. I just have 2 light stands w/ 2 500W halogen bulbs on each stand washing across the green screen.Regarding other issues, this is video that was captured in Vegas, no other effects on the layer, or event but Chroma Blur and Chroma Key. Even if I remove Chroma Blur I still see the same effect.
Next time I will definately take more time w/ the lighting, but unfortunately w/ this shoot I was forced to do a quick make-shift set, and the key turned out bad because of some shadows created by set props. In the past I’ve done mostly individuals w/ medium and medium close shots against green, so it’s pretty easy to pull. This is more complicated, and I’m forced to do a bunch of masks to get rid of shadows, which I am fine, but this whole color shift is driving me crazy.
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Understood.
I dont know the size of you screen but….
with an 8×8 screen I recommend this setup with what you have
If you can get the subject 8 feet away it helps a lot.
The lighting you have is fine .Sounds like its some home depot worklights at $39.95 a tree
Thats OK but take off the protective grills. also open the glass cover and rotate the bulb so the molding tits are facing the back.(Dont touch bulb with bare hands !!)
Also what helps is get some cheap shiny aluminum flashing (home Depot)
and rebuild the refector. The stock one creates bad reflection artifacts.Place the lights about 10ft or more from the screen and 45 degrees to it.
Off the side, approx same distance as subject.
point the 4 lights at the 4 quarters of the screen. The left lights point to the right side, right ones to the left side. Depending on the camera… Use the zebra setting and open the exposure until you just see zebras. Now move the lights around till you get an even zebra wash.Use something to keep the lights from hitting the subject.
Light the subject from 45 degrees angles as well but use something to block its light off the screen.
Shoot , try againLet me know if there’s a difference.
Thanks Zipedit -
Zipedit,
Thanks for all the great tips. I’ll definately impletement them the next time I shoot. I really like the idea of adjusting the iris to get zibra striped to check an even green screen. I’m shooting w/ their Panasonic DVX100. Nice camera. I posted some screen grabs just to show you how I REALLY don’t like the spill supressor used by Vegas Chroma Key.
http://www.shiftstudentministries.com/images/before_key.jpg
http://www.shiftstudentministries.com/images/key_not_adjusted.jpg
http://www.shiftstudentministries.com/images/after_key.jpg
These were quick grab, not fine tuning, just used to show my issue.
Thanks for your help!
Josh
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I see what you mean.
Are you using the color picker (eye dropper)?
Because if you pick a spot on the green screen before you adjust then the screen should look black not blue
If so then pick a square the size of her head , right above her head..really close without touching her hair.
use the mask check box and it will also show bad areas of lighting.
get the subjects to be all white and the green screen to be black.
If the lighting, distance spacing, amber back fill is all done right then
you should be able to get a good key with only moving the sliders about 20%
of their travel.
Your subjects are so close to the screen that there is an insane amount of spill on those edges. All that wood should be leaning on something in the air above the set and 10 ft away from the screen.
Notice the key is good across the top of the helmet and on 1 edge of the wood.
Its the reflected green that is killing at this point
Do my yellow/amber light trick from behind the subjects to neutralize the green spill you have spill on the edges of EVERYTHING! the way this is setup.Put her hair in a pony tail or bun and I think you can make this work.
There is potential !!
Good luck
Zipedit -
Thanks for the tips.
The room really isn’t that big, so the most I can really have the actors or anything away from the green wall is 5-6 feet. They have a make shift light box hanging from the ceiling above the actors (5-6 feet from the wall). I may try and rig some amber gels to it. Do you think that would help, casting amber light directly down on the actors from above?
Now that I look back on it, I should of just shot the whole thing on green then photoshoped and compositied the rest. No props at all, just the actors. Considering they are really just background and never really come in to play, they are just there casting bad shadows and darkers shades of green :O) You live and you learn!
This is one of my first attempt shooting the shots myself. I’m pretty versed on the editing and computer side. This is making for a lot of late hours. I ended up downloading the demo version of After Effects and am using a combo of keylight, and adding and subtracting masks, & precomposing to get the best key for each scence. Lucky most of the actors aren’t moving, so I can mask out a lot of the bad shadows and green. Only in some parts do I use need to use animated masks. I could do this in Sony, and I attemped, but the color shift in clothes was really messing me up.
Well thanks for the help, like I said this is definately a learning progress, but this is forcing me to get more creative which is a good thing! With Ultra I probably could of just pulled a key and what fun is that? :O)
Josh
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