Keying White
by Steven Gladney
on
Aug 28, 2008 at 7:07:27 pm
I am planning on doing a shoot in studio and want to shoot on white screen (instead of green screen) to achieve infinite white look. I've done some test shots and the footage comes out fine, but I did ultimately plan on being able key the white screen and frankly, have no clue how to approach it. Here is a sample of what I'm going for:
I understand how to key green screen footage (keylite) very well, but I'm figuring it's going to be a different process for white screen (figuring some type of alpha or luma track matte or something). Just not sure how to do it. Any help would be appreciated. Thanks.
Re: Keying White by Steven Gladney on Aug 28, 2008 at 8:39:23 pm
Thanks for the input guys.
Kevin, the samples that we shot are lit correctly (background is definitely lighter the lightest hi-light in subject) but I'm not very familiar with the luma key effect and not sure how to make the controls work. Suggestions?
I did try Darby's suggestion and it looks like it will work well, but I'm rendering out a sample now to try. My only concern with the Extract filter is it doesn't give any kind of edge feather controls, but being it will be on a white background anyway, I think it will still work fine.
Consequently, I would like to hear any additional feedback regarding shooting on a green screen and replacing the background with white. I've done a little research online and a few things I was reading was suggesting that if you are going for an infinite white look, its better to shoot on a white screen (which I had already). If you think I'll pretty much get the same effect keying off of a green screen (which I'm much more familiar with) then please let me know.
Re: Keying White by Kevin Dearing on Aug 29, 2008 at 3:24:12 am
Hi Steve,
I'd give a lot more weight to what Darby says as I'm an AE newbie and am not even doing this stuff for a living anymore (I did 12 + years ago but not now.)
Anyway, for chroma keying green or blue and replacing with white I've found that as long as there is a good distance between the screen and the subject (and the lighting is good and even on the screen) you will get little to no color casting.
The other thing that I tried a while ago in response to a similar post was to use the Color Keyer.. I selected the white from the background and it turned out ok.. Not great but my test footage was horribly lit.
But again, Darby is the pro so I'm sure that what he says is a better way..
Re: Keying White by Dave LaRonde on Aug 29, 2008 at 3:44:24 pm
[Steven Gladney]"If you think I'll pretty much get the same effect keying off of a green screen (which I'm much more familiar with) then please let me know."
Here are the questions to ask yourself:
• Are you confident in your ability to pull a good chroma key?
• Can you eliminate telltale green spill on the subject?
• Have you eliminated issues with refractive surfaces, like green showing up in a subject's thick glasses?
If you answer "yes" to all the above, I'd say you can proceed with a chroma key. You can always run a test on your studio setup prior to the Big Day to confirm this.
Dave LaRonde
Sr. Promotion Producer
KCRG-TV (ABC) Cedar Rapids, IA
Re: Keying White by Darby Edelen on Aug 28, 2008 at 8:10:54 pm
I find that the Keying > Extract effect is usually good enough for removing white backgrounds. Just be sure that there is no white in your subject.
An alternative is trying to create your own grayscale matte for the subject from the footage by playing with Color Correction > Curves or Color Correction > Levels and Color Correction > Tint and then using it as a luma track matte. Most of the concepts are the same as with green/blue screen shots, just simpler. Use a garbage matte, etc.
Re: Keying White by Jordan Montreuil on Aug 29, 2008 at 5:22:28 am
One thing I have done on a few occasions such as this is duplicating the footage and applying the Threshold effect to the duplicate. Fiddle with it until only the background is white and then apply that as a luma matte for your original footage. I often have to add a blur to the matte to smoothen the edges because the Threshold effect often makes it pixelated.
