Green Screen Backgrounds

Green Screen Backgrounds

Comments

Peter, One of the

artsmith's picture
Peter, One of the best articles I have read for some time. My own experience with 'chroma'-screen' is in animation, so information regarding green-screens,(physical), has not yet been my concern to any great extent. One thing I would recommend, though, is for prospective users to try and determine the limits of the hues of green which are effective in the process. I animate travelling lines onto maps, on occasions, to indicate routes being taken, and shown, simultaneously by 'live-action' behind the map, which is actually a graphic of a skeleton nature, designed to be seen-though except for the features, which are marked out by white lines. (Colours, such as red, tend to bleed and behave in ways which are sometimes hard to predict). However, it is impossible to predict where lines are to go against a featureless green background. So, the line to be animated over, frame-by-frame has to be marked out, initially, in some other way. In the software which I use, there is s surprising tolerance of various hues of green (and blue), and it is quite possible to select a green which is different enough to mark out the proposed route against the 'chroma' background, but still fits within the tolerance limits of the 'chroma' colour. That way, the authetic 'chroma' green and its slightly different variant are easily adjusted to be invisible in the finished product. Research involves merely, picking through the greens available from any computer colour-device, determining the limits by experimentation (eg creating colour-patches' and placing on your video editor's timeline), and taking it from there. Once noted, the usual code of three 'numbers' pinning down the exact greens which have been arrived at by experimentation, are easily recalled to the screen, when needed.

I have a cloth "green scre

alpha1's picture
I have a cloth "green screen" (and also a blue one). Although I have not noticed it so much in video, when I have tried to use it for still photography, I notice that around the edges of the main subject, I get a greenish tint to it (especially noticeable in the hair). I imagine this is the result of defects in my lighting, but can anyone give me any hints as to how to avoid this effect? Thanks.

is there info on how to ed

PZunitch's picture
is there info on how to edit footage FCP? Lay your background on V1, and your green screen on v2. Then drop the key effect you want to use onto the v2 track. Effects > video filters > key. (there's a few to choose from, and even more that you can buy from third parties). if you then go into the clip and click on the filter, you'll probably be asked to set the key color (use the eyedropper), or key range. If there's a "view" option, switch it to "composite" at this time. Then adjust the black level, white level, gain and or smoothness (again, whatever is offered) until you get a smooth image. Beware of buzzing on foreground objects and adjust these levels to minimize it. As far as which key effect to use, you'll have to experiment. Some will work better on some shots, while others work better other times. If you have the ability to spring for a 3rd party plugin, I highly recommend the DVmatte Pro from DV garage. I use it daily and it's highly forgiving of uneven green, etc. I'm sure there's more editing tips in the videomaker archives, but hopefully that will get you started. --- when I have tried to use it for still photography, I notice that around the edges of the main subject, I get a greenish tint to it (especially noticeable in the hair). This COULD be because of bounce light bouncing off the screen and onto your subject. If so, lower the light on your screen or move your subject further away. Probably not the case though. Most likely it's the green light refracting through the thin strands of hair at the ends of your subject's hairstyle. matte chokers, spill supressers and edge tint are all supposed to help with that stuff, but it's not always easy to find a good balance of what removes the green without removing too much hair. Try edge tint, and soften the edges off the key a bit. If it's a still image, you might have better luck manually modifying the green channel in photoshop to paint out the spill from the unwanted area. Hope this helps!

Green Screen Fabric

runetic's picture

I have tried experimenting with a fabric green screen.  I have now realized that my backdrop is going to require additional equipment to hold the fabric taught. The article refers to fabric which has a bacnking.  Mine does not.  Do you have any suggestions on specific green screen fabric with backing?