Blue screen or Green screen
 

The heading says it all.

A part from making sure that the subject matter does not contain the same colour as the background;

Is there a difference between them (apart from colour)?

Is one better than the other?

Is one used more in Film than Television?

What is the best way to light a blue or green screen?

So many questions, I hope they could be answered,

Ed Smith

>>>What is the best way to light a blue or green screen? <<<

The "key" in Chromakey is to light evenly--no shadows or "hot spots"... so soft lighting ideally. Ross Lowel talks at length about soft light sources in "Matters of Light and Depth"

If you wind up with ugly artifacts in your blue/green screen then you'll have to use the "garbage matte" tool in FCP but now we're talking time and effort.

Mike,

Is that a book your mentioning or something else?

Ed,

Besides green and blue there is also orange and
perhaps some other colours. It mostly depends on
what colours are in your "objects" or people that
you are shooting. Blue is the furthest away from
human skin tones, so that's why you see that
a lot used. If you have blue clothing or dark reflective
colours (which can sometimes look like blue) it might
be best to go with a green screen.

Now with DV I thought one colour was also assigned
more bits (or less compressed, which ever you want
to call it). I'm thinking it is green, but I am not sure.
If it is green, it might be wise to use green screen
for better green quality when you get to the computer
stage to remove it. Maybe some testing is in order
here. Small portable screens are easily and not
very expensively rent! You can even buy screens
that are blue on one side and green on the other.
This way you can test before you buy. Or perhaps
just rent the screen for the days you need it!

Good luck.

Ed here is a link i found it might be of use to you
http://www.seanet.com/Users/bradford/bluscrn.html

Yep, it's a book. $28.95 on amazon.com--once in a while you see it on half.com--it's a great book for all types of photo, cinema & video lighting--he treats it as an art form and it's quite fun to read (not some dry technical text).

Matters of Light & Depth
by Ross Lowell
Paperback - 224 pages (April 1, 1999)
Lowel-Light Manufacturing, Inc.; ISBN: 0966250400 ; Dimensions (in inches): 0.53 x 8.96 x 9.00

Cheers guys for all the responses, they will help greatfully.

It was just curiosity which made me pose the question, plus I have been using an old red blanket to shoot anything which needed chromakeying.

I think in the coming monthes I will invest in a proper screen (probably blue...or... possibly green!).

Thanks again, all the best,

Ed Smith

that's an awesome link, Ian! They raise an interesting point about the risk of light spill on the subject from the green being more objectionable than blue spill.

I like where they say the trick is in lighting the foreground without screwing up the background.

Lots of good info there.

green screen dance floor
 

Heya all,

Here is prob the most peculiar question you have been asked, but why not. I want to work a way out of doing a green screen effect on a dance floor, as in the floor being a green screen and people dancing on it, but making the floor look all wild.

Now i am not sure how to light it, i may have to build something and light it from underneath but i am not sure...


Anyways, lets get the brains tinkering, as i am totally new to green screening, production and post.

Thanks all,

Zac

What angle(s) will you be shooting the people dancing from? Straight on or from above?

- don

That's going to be tricky to light, as the shadows cast all over the floor will mess up the green screen effect. I'd light the people, low, from the side, and if the budget allows, build a fake floor and light it from underneath. Sounds like quite a project, let us know how it works out!

They'll have to dance in their socks.

I wish you luck.

I would try lighting from beside the camera at all times, that way the shadows would be behind the cast. It still wouldn't be perfect, but it's the cheapest and best way I can think of.

-Nori

If you use keying software such as Ultimatte, you can deal with the shadows OK. The problem is that the dancers are going to be moving around closer and further away from the lights, and there's no way to light the background separately from the people. If you just light the whole thing with soft lights, you might be able to get something out of it. What you need is a floor made out of opal glass that you can light from underneath with green-gelled lights. I bet that would cost a fortune.

Just so you know, to get good results this isn't going to be cheap.

I would use lots of either softboxes, florescent fixtures or pancake lanterns.

Flourescents maybe the least expensive per instrument, BUT, here's an example: http://www.kinoflo.com/product/blue%20and%20green%20screen/bluegreenscreen.html
of how they light a large green screen wall. DOZENS of instruments.

You'll need less softboxes or lanterns. I really like the lowell Rifa-88 w/ 1000W lamp.

Could you do it outside?

Yes. i would not light it from beneath. Mainly because you would then most probably get a bad green hue to the dancers. Something that unless you are shooting on film would be very tricky to key out properly. You want high contrast between your foreground and the greenscreen, and the less material you have to do this difference with (ie. resolution) the more careful you should be.

Now, people would argue that "hey, i can green screen perfectly with my DV camera" and i do not argue here. But to greenscreen from a wideshot is a whooooooooole lot different than greenscreening a closeup.

My suggestion would be to if at all possible, build the floor as it should appear in the video, then use greenscreen for the surroundings.

Very good point...I forgot about the green light coming up through the floor to the people. And your point about long shots being difficult to key is well taken. Unless you're using at least a DV50 format, it's not going to be great. We do fairly wide shots, usually one or two people on camera, and I can get from just below the knees up and still get a good key; but the longer the shot the more difficult the key.

Green screen compositing: What tools on PC?
 

Hi,

What do I need to start compositing with a green screen? Where can I buy the green screen material in New York City?

Notes:
I have VV3, Studio 7, Photoshop and an assortment of MiniDV cameras.

Thank you.
Michael Wisniewski

Here is a link to a tutorial on green screen lighting. The author makes reference to material he used in the tutorial. I hope it helps. Software questions on programs for PC can be posted in the PC editing forum.

Vegas 3 does good keying and you can make adjustments to fine tune it ... you must shoot a good green screen .. use the BEST camera you have - 3 chip is better then 1 chip ... if you didn't shoot a good green screen then you can use photoshop BUT it is tidious work (frame by frame )

Chroma Screen help
 

Hey all,

I've been presented with an offer to possibly film/edit/produce a pilot tv show, given its nature, we're not really planning upon using a set studio location, so i'm looking to purchase a portable chroma screen for a reasonable price

Does anyone know of a source/dealer from which to purchase a complete kit (screen and stands) from? So far, i haven't seen much out there, save for some generic low-cost photo stores on ebay, and i'm looking for something of quality manufacture.

i know...i know...you do get what you pay for....
~Mike

Mike- Try www.backdropoutlet.com , or call them at 1-800-466-1755. Not exactly cheap, but I have seen worse.

Greetings

I have found a very resonalble priced portable system at Elite Video. They are pretty well known in this community. Check out there web-site at http://www.elitevideo.com

A friend of mine has this portable system which is blue on one side and green on the other. Reel handy idea. I have there cromakey background which is 20 by 13. I plan to make my own portable kit because I was to cheep to get the one they have even though I think it is a good price.


Marcus

Thank you both! Especially the tutorial, that was great. Just what I was looking for.

also look at dvgarage's site. They have several tutorials about greenscreen and also have a plugin for AE that does a great job for keying.

Rob:D


PS- is there a reason why I dont have all the options to post links and pictures? where did it go.

Tech Green
 

Can I take a sheet of chroma green that I overpaid for and takeit to a hardware store (Home Depot, Lowes, etc.) and have them color match it? Would this work as well as the $65 a gallon for chroma green?

Maybe I need to clarify, if I color match the Chroma green for keying, would this be possible or is there a certain way the "TV" paints are composed that prevents color matching?

You should be able to do that - if you add the key in an NLE, the colour itself does not matter much, as long as it is evenly lit and will be easy to pick out.

Green and Blue are the traditional colours to use because of the component signal (RGB), where before computer technology took over, you would just remover either the g or b cable and insert the composite background. Red is obviously not a good colour to use since it is too close to some skin tones.

There are threads you can search for about chromas and how to light them properly.

Hope this helps.

Will this stuff work for a green screen?
 

I would probably tape it up on a wall in my garage or basement. I need a cheap solution, I was wondering if this was the right color. It says sage, but tech green.



http://www.bhphotovideo.com/bh2.sph/...ID=F5A91D00850

If you have no budget but plenty of time, you can find a solution that won't brake you. The best reason to use green or blue is that most compositing software is designed to see it and extract it easily and will also provide you with tools to do some spill supression, etc. There is always a brute-force solution, though.
If you are on a shoe-string budget you can use anything as long as there is enough contrast between foreground and background (luma or chroma) and you have decent compositing software. If you can afford to buy something like a green screen, go for it, but if your budget is tiny try shooting some tests and see if it is really necessary. Hope this helps and good luck!


~Brad

Thanks for the advice Brad. I went ahead and tested my old blue posterboard bluescreen that I used with a Hi-8 camera before. The results were subpar, so I bought some green paint and hit it with 1000W worklights. It looked pretty good for a $20 solution. I think that the paper would have been too much of a hassle to keep wrinkle-free. I'm planning on getting some kind of smooth paneling, maybe particle board, and painting myself a bigger screen.

Poor mans bluescreen?
 

I was just thinking about using one of them big blue tarps that you see all over the place as a bluescreen, would this work at all?

The only problem I see is that they have a texture to them, and that might affect the chroma key....

Other then that, a 20x16FT one at the home depot is only $18.

http://www.homedepot.com/prel80/HDUS...SearchStr=tarp

They are also fairly reflective compared to say plywood and paint, but if you light it really flat you might be able to get away with it.
Let us know how it works ;)
Don

BTW, is the reason for fewer posts lately that you've gone back to school or???

Yeah, mostly school, and I haven't been shooting much video lately. =/

I'm going to buy the 9x12FT one for $8 (which is still a decent size, even though 16x20 is huge) and see how it works...

My neighbor has one in her yard, and thats where i got the idea from, and it didn't look too shiny/reflective to me....

As I said it's shinier than plywood and flat paint but it might just work. You might also try "dulling spray" that you can buy at most hobby stores and it does just what it's called. It dulls the surface reflection. I use to use it many many years ago when I would shoot glass or metal for catalog stuff along with the right lighting of course.
Don

Nah Alex... don't do it. It WILL be too shiny... absolutely. The BEST possible option is to paint a smooth wall with chroma green or blue. (DV likes green best by the way.)

If that isn't possible you are left with two pretty good options.

1) Get a roll of seamless paper in chroma green. If you live close to any major city then check with photographic or cinema supply. You can get a roll of seamless background paper in "stinger" which is chroma green and it costs less then $40 for a roll which is 9' wide by THIRTYSIX feet long! Meaning it's practically DISPOSABLE for each shot!

To get a uniform background put two loops of rope around your trusses in the garage (or bicycle hooks)... then run a metal pipe through that so it hangs near the ceiling. You are going to run that through the cardboard tube that your paper is on. Be sure to clamp the paper with the appropriate amount coming down or else the weight of the paper will unroll the entire roll right before your eyes! It's best to have somebody help you set this up the first time and every time.

Option 2) is chroma fabric at $17 per yard. You'll need AT LEAST two yards and preferrably 3 so you can hang it up on a wall and have enough to curve down, out, and over whatever your talent is standing on.

Finally the most crucial part of all this is even lighting. You can get that with fluorescents. I'd recommend you get some Kino tubes for $20 or so each and put 'em in normal household fluorescent fixtures. You can use these for other purposes as well... such as softboxes.

That about sums up all my advice... everything else gets pricey.

Alex, in case Don and Matt haven't turned you off it enough, those blue tarps are shiny like glass. Don't even waste your time on it.

Aye aye. I'll check out some of them options, Matt, thanks.

A friend of mine pulled off a nice bluescreen with blue sheets of posterboard, so I thought if he could do it with that, then I could do it with this, heh.

Matt,

Know where the chroma fabric you mentioned at $17 a yard can be purchased from online?

Filmtools.com has chroma fabric listed at $17.90 per yard and it's 60" wide.

Studiodepot.com has Rosco chroma listed at $95 for a piece 48" wide by 10 YARDS long.

I got my price from Cine Services here in St. Louis. They have an EXTREMELY limited stock onhand, but they did have chroma green and blue... as well as the seamless paper. At their store the chroma fabric is 84" wide (6') and that's nice... plus it's just $17 per yard.

They do have a website at Cineservices.com and they'd probably be tickled to get called in orders from other cities... so if you do call them be sure to tell 'em matt gettemeier sent you!

Seamless paper really is CHEAP. The thing about it is that you need to have a friend help you so you don't CREASE it... if you wrinkle it up then FORGET your chroma key. You MUST have your metal pipe hanger ready to go before you start.... also be sure to get those pony clamps (or similar) to hold the paper from completely unrolling!

If you guys want to take this chroma keying to the next level then get yourself some colored fluorescents... green or blue tubes... and pop 'em in ordinary hardware store fixtures. Then flag 'em so they get ONLY the background and keep your subject independently lit in the foreground... even before you dump that video into your computer you'll be getting giddy at how well it will work. When you look through the eyepiece or LCD you'll see that the green areas don't even look real... it looks like a flat digital background from the start. Hence it makes chroma keying work perfectly.

That's how all the pro's do it in Hollywood... and those tubes are less then $25 a pop! If you're over 25 then I don't have to tell you how cheap fluorescent shop lights are... just be sure they have the high-frequency electronic ballasts and they'll work fine... even if they don't look like Kinos.

If you have at least $100 do a search on ebay. I purchased a cloth 12'x12' greenscreen online (with gromets for hanging, etc), for less than that. Might be worth your time.