Comments

MichaelS wrote on 3/27/2005, 12:57 PM
Many thanks to Keith!

This is the type of tutorial that I'll print and put in the back of my notebook/manual for future reference. Good job.

Thanks.
farss wrote on 3/27/2005, 2:54 PM
Good stuff but I'm wondering about the validity of blaming the problems entirely on DVs 4:1:1 sampling. I'd like to see a comparison of how say footage shot on a 709 and downconverted to DV keys compared to the same scene shot on a prosummer DV camcorder. I'm suspecting that very few DV camcorders come close to what DV is capable of.
No one makes mention of the impact of poor camera optics on being able to get a good key. Just take the case of the flyaway blond hair, it's in high contrast to the screen and I'd bet cheap glass is going to do more harm at the blue/yellow transistion that the DV chroma sampling does.
Bob.
mjroddy wrote on 3/27/2005, 5:22 PM
I know I get excellent keys with my 4:2:2 and BetaSP setup. I really have to struggle with DV. And I have yet to get a DV key as good as my Beta setup.
Anyway, I read somewhere - a long time ago, that you should sample the colour ranges closest to your subject's hair line. You didn't do that in you tute. Was this just another opinion from the guy who gave me the advice?
Spot|DSE wrote on 3/27/2005, 5:30 PM
I don't know that I'd classify it as an "opinion" but rather a technical trick for those times where you are having difficulty cleanly keying. In a back lit situation, it's not as valid, depending on how hot the backlight is, because it could be 'reverse' spilling, in terms of the subsampling. There are a lot of tricks that can be employed to get better keys out of vid, but at no time, will DV ever key as well as what you're used to with 4:2:2. Just not enough information there to do as good a job when comparing.
MarkFoley wrote on 3/28/2005, 12:34 AM
Thanks DSE...just when I thought I knew about most of the filters in Vegas, this article shows a trick I could have used in my last Chroma Key project where I had slight problem that Chroma Blur would have worked....
kkolbo wrote on 3/28/2005, 5:11 AM
The article only addresses the issue that comes from the sampling. Of course, the better the light, the better the optics, the better the processing the better the key. Smear is a real issue with chroma keying. DV just aggrevates it. A good camera with less smear will improve things. You still are not going to get a key that looks as good as if you were working directly from a 4:2:2 source and file.

K
Arthk wrote on 3/28/2005, 11:43 AM
I keep having problem with jaggies when using the chroma keyer in vegas 5,i was thinking about chromanator for the spill suppressor,but after reading keith's tutorial,i've been getting better keys without the jaggies, the info is simple and to the point, good job.
apit34356 wrote on 3/29/2005, 7:31 AM
Nice tutorial on chroma blur with chroma keyying.

DSE, outside the optics and 4:2:2 issues vs. 4:1:1, I find that using masking, secondary color filters, and using the sliders on the chroma key color increase the "box" color range very usefull.
I usually find that a number of keys are required in any scene with movement or where subjects wear white or very bright clothing. Rapid movement is really a pain. I believe DSE touched base on using secondary color filters in one of his chromakeying tutorials.