What are the basics of green screen photography?

Reiko Peaches: What are the basics of green screen photography?
I just bought a green “chroma-sreen” for photography. Does anyone have helpful-hints for the novice green-screener? I have 16 years in photography, film & digital. I also have studio lighting and various other equipment. Get as technical as you want – I’m all ears.

Answers and Views:

Answer by nikonfotos100
For the video you can use the green screen but to shoot still photography you will run into problems. You will notice this when shooting people and you will not get the “neon green” cast out of your photos (skin, etc) unless you want to do a lot of work.

My suggestion is to use a pure white backdrop for this type of work you might want to do.

A friend of mine who worked for an advertising agency for over 7 years asked me why I wanted to use a “green screen” (to play and experiment). She said use white and then showed me.

Hope this helps,
Kevin

Answer by digitaldiva1229
Well, Nikonfoto is right about the green cast but not so that is will take away the ease and joy of working with green screen.

Mainly just set up your lights to get the best exposure of your subject. Like always you will be lighting the subject; not the back ground. You want the best skin tone you can light.

I have found that when I do have a green cast it us usually a problem when my client is wearing white. It is easy enough to correct in Photoshop. Layers/adjustment layer/ hue saturation. Go to green and lower the saturation level a bit until it looks right. Not a big hairy deal.

However I have found when photographing metal objects there is more of a cast but the same method works great.

As for using white for your background, you do not get a clean erase. The magic erase too will erase everything else that is white. Tennis shoes, stripes in clothing, etc… Hence the neon green.

Answer by antoni m
as above its a hassle, your using moving picture tech for still pix and it dont really work that good

as above use white, with a curve at the bottom (where it touchs the floor) so theres not line or horrizon so to speak

im geussing you know this, get exposure with a meter, a gray card, or a hand reading plus a stop,

Answer by Jonas M. Rogne
A green-screen is useful when using some sort of automated technique to easily and quickly remove the background. However it has some drawbacks to use automated tools for keying or selecting.

I would use green (or some other colour) for video (as I don’t want to manually mask 3000 frames), but for a still photo I would use a neutral grey or white background. The reason why I say grey is that white can tend to “bleed” light and overexpose the edges of your subject (similar to the green colour cast).
In Photoshop would then use a vector mask or a layer mask (or both, depending on the subject) to mask out the background.

For something more complex like hair blowing in the wind you wouldn’t want to paint the mask manually 😉
For hair the simplest would be to use the extract tool (on the filter menu). It requires a couple of tries but gives an ok result. Note that this tool also tries to remove the colour cast. I would use it just for the hair and mask the rest manually for the best result. – Make sure there’s enough contrast between the hair and the background.
You can also use the channel mixer (or the new black and white adjustment layer in CS3) to make a black and white mask for the hair – use dodge/burn to clean it up. Then you could load back up as a selection. This is pretty advanced though but can give better results than the extract tool…

Anyway, no matter what you do, try to make the background as out of focus and as evenly lit as possible.

To remove colour bleed you can as someone suggested reduce the saturation on the edges selectively for the green colour.
Another manual option is to use the colour replacement tool, or the saturation tool (set to desaturate) to “paint away” the unwanted colour.
Also, if you’ve applied the mask to the layer there is a nice automated way of doing it by going to layer > matting > Defringe… (also an option for you there if you used a black or white background)