Best way to perform a good minidv chroma key?

[Anonymous]

well guys, im starting now with a little shortfilm, and i would like to do some chromakey shoots. I’m working with DF, and i ask you what workflow do you use for a MiniDv Key… ¿any special plugin?… ¿blue o green, what is the best? I see Chromator in use and it apears very powerfull… anyone does test it?

Thanks for all. 😉

(sorry for my english)

[softer_vb]

It depends on the footage ofcourse. For starters bluescreens should never be shot on DV or SP beta for that matter 4:1:1 sampling rate is way to low to get the necesary color data that u need for a good bluescreen. But if u have to then u have to, i would start by bumping the color depth up to 16bit so that u can generate some real subtle tonal difference where its need it, the i would give to footage a slight blur 0.25, 0.5 max, i would maybe split to channels and only apply the blur to say maybe the red ..hard to say when i have not seen the footage. Once u got the matte and u find the edges to fuzzy, compressing the levels should make for a stronger edge, when u are happy with the matte apply it to the orignal footage without blur.

[Anonymous]

Well, I agree it’s not easy to get a great key off DV, but it’s not impossible.

If you have the Fusion books, there’s a tutorial in the courseware book about dealing with 4:1:1 video and keying, and it works quite well. The key is that any blurring you apply should not be done to the RGB image, but to the UV components of the original YUV image. The tutorial has you convert the original video to YUV, shrink it 1/4 size with no interpolation, then expand it back to full size with interpolation. After this you recombine the YUV using a channel boolean with the original Y component of the original footage, then convert it back to RGB colorspace.

That’s a quick summary – the courseware probably explains it better. But, using this I’ve really had very few problems keying DV footage I’ve shot.

[Anonymous]

and by all means try to use green screen for keying. Green gets lots more info and with your miniDV you need as much as you can get. The tips on the UV are right. Try to shoot your actors at some distance to your green screen (as further you can move them) to minimize colour spill (or you’ll eat your hart out later 🙂 Don’t let your camera do any enhancements on the picture like sharpening, try to shut off all the picture enhancements you can this all destroys a valuable picture information and introduces artefacts that you don’t want in the picture.

Hope it helps a bit.

😛

[Author]

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