Blue Screen vs. Green Screen

Brad Doan · May 28th, 2003, 10:54 AM

Actually, most compositing software these days is sophisticated enough that it isn't really critical. I was recently involved in doing effects work for a (low budget) film where a back-lit white sheet was used. Keying out the sheet proved to be no more difficult than green screen, it was just a question of luma-keying rather than chroma-keying. My experience has been that as long as there is enough contrast, you can use anything you want. That said, if you can afford it, use it.

~Brad

Rob Lohman · May 30th, 2003, 06:42 AM

and do some tests first....

Rick Spilman · May 30th, 2003, 07:11 AM

Jon Jackman had a very good article in DV magazine about keying recently.

http://www.dv.com/features/features_...03/jackman0603

One comment he makes is about software & hardware. We all spend so much time talking about the screen, the color and the lighting that the software or hardware seems taken for granted.

One of the major problems with keying in DV is the color space - 4:1:1. When keying in 4:1:1 it is difficult to avoid "stairstepping" and the "jaggies". Some hardware and software plug-ins interpolate the color space upward to 4:2:2 (Canopus Storm, RexRT) or even 4:4:4 (Matrox RTX 100). The difference is huge. There are also a number of plugins which do similar magic through software. If you do all you can with screens and lighting, and still aren't happy with your final key, you might want to check them out.

Rob Lohman · May 30th, 2003, 07:17 AM

NTSC DV color space is 4:1:1 indeed. PAL DV colo(u)r space is
4:2:0 actually (and no, we don't loose all the information in that
last sample)

Jeffrey Baksinski · May 30th, 2003, 10:46 PM

It's best to shoot green screen in most cases. Human skin has too much "blue" in it and it becomes a pain with pulling hair and such.

The biggest thing to avoid is "spill" no matter which color you use. If your lighting is too hot and your screens are too close to your people, you'll cast greenish light on them and make it that much harder.

May 30th, 2003, 06:42 AM	#17
Rob Lohman RED Code Chef Join Date: Oct 2001 Location: Holland Posts: 12,514	and do some tests first.... __________________ Rob Lohman, visuar@iname.com DV Info Wrangler & RED Code Chef Join the DV Challenge \| Lady X Search DVinfo.net for quick answers \| Buy from the best: DVinfo.net sponsors

May 30th, 2003, 07:17 AM	#19
Rob Lohman RED Code Chef Join Date: Oct 2001 Location: Holland Posts: 12,514	NTSC DV color space is 4:1:1 indeed. PAL DV colo(u)r space is 4:2:0 actually (and no, we don't loose all the information in that last sample) __________________ Rob Lohman, visuar@iname.com DV Info Wrangler & RED Code Chef Join the DV Challenge \| Lady X Search DVinfo.net for quick answers \| Buy from the best: DVinfo.net sponsors

May 28th, 2003, 10:54 AM	#16
Brad Doan New Boot Join Date: May 2003 Location: Phoenix, Arizona Posts: 14	Actually, most compositing software these days is sophisticated enough that it isn't really critical. I was recently involved in doing effects work for a (low budget) film where a back-lit white sheet was used. Keying out the sheet proved to be no more difficult than green screen, it was just a question of luma-keying rather than chroma-keying. My experience has been that as long as there is enough contrast, you can use anything you want. That said, if you can afford it, use it. ~Brad

May 30th, 2003, 07:11 AM	#18
Rick Spilman Major Player Join Date: Dec 2002 Location: Jersey City, NJ Posts: 366	Jon Jackman had a very good article in DV magazine about keying recently. http://www.dv.com/features/features_...03/jackman0603 One comment he makes is about software & hardware. We all spend so much time talking about the screen, the color and the lighting that the software or hardware seems taken for granted. One of the major problems with keying in DV is the color space - 4:1:1. When keying in 4:1:1 it is difficult to avoid "stairstepping" and the "jaggies". Some hardware and software plug-ins interpolate the color space upward to 4:2:2 (Canopus Storm, RexRT) or even 4:4:4 (Matrox RTX 100). The difference is huge. There are also a number of plugins which do similar magic through software. If you do all you can with screens and lighting, and still aren't happy with your final key, you might want to check them out.

May 30th, 2003, 10:46 PM	#20
Jeffrey Baksinski New Boot Join Date: May 2003 Location: North Hills, CA. Posts: 7	It's best to shoot green screen in most cases. Human skin has too much "blue" in it and it becomes a pain with pulling hair and such. The biggest thing to avoid is "spill" no matter which color you use. If your lighting is too hot and your screens are too close to your people, you'll cast greenish light on them and make it that much harder.