Chroma - Green or Blue?

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DAVE M
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Joined: May 17 1999

I've done loads of chroma work before and I'm moving from a (blue) fabric backdrop to a painted cyc/wall.

I use 3 chip cameras, Mx50 chroma to DVCam/DVCpro.
or
prem 6.5 through Matrox RTX100.

My question is would I be better going for green or sticking with the blue? I think that green might be better for DV?

I'm aiming on using Rossco Chroma paint - anybody know what the coverage is per 3.7ltr can? I can ask the supplier but someone here might know.

harlequin
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Joined: Aug 16 2000

to the best of my knowledge

blue : analogue
green : digital

Gary MacKenzie

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RichardB
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Joined: Aug 27 1999

It's entirely up to you.

It makes much more sense to look at the costumes and props and key away from those colours than to worry about whether green is better (green is the colour the luma is keyed to and is meant to be marginally better) than blue (blue is supposed to handled light skinned people and blonde hair better.)

Roscoe paint I think is an expensive luxury: I've had excellent results from 'standard' paint mixed to as pure a colour value as possible- go to a small paint store where the mixer understand how to use the colour machine, or else you risk the B&Q employeee looking at you as if you're mad ('but what COLOUR do you want? I could do you Avocado Crush...')
At the end of the day the lighting will make or break your key, and that's where my extra money would go.

I haven't used the Mx50 but you're on the right track by wanting to do the mix live: hardware will be better than software. A good intermediate trick, if you can't mix to the effects footage live, is to set the key mixer to output the solid green and mix into that, so when you come to key in post the bg will be a perfect uniform value.

The bad news is that DVCAM/DVCAM Pro are not going to give you any better results than standard DV, the colour sampling is still 4:2:0 and the Codec is notoriously bad for this type of colour work. The camera to find is the DVCAMPRO50 which uses two codecs and ups the sampling to 4:2:2, while lowering the compression to 3.3:1

Of course, the best way around this is to do the mix live, it's always the best way and the only real way of knowing if all your plates fit together.

Hth
Rb

Pt2: Just looked at what I've written and maybe I've not ben completely clear on the DV/DVPRO50 issue

DVCAM samples at 4:2:0 and 5:1 which is awful for colour work, UNLESS you are feeding the fully mixed image into it from your mixer, in which case it's no worse than any other of your footage.

The mixer is probably (esp if its an older model) only operating in a 4.1.1 colour space BUT if you can feed an uncompressed camera signal in then the quality is higher because the source footage is better. (Of course, this assumes you can get a nice clean signal out of the camera into the mixer, if it's been processed prior to the feed out then you're back to square one.)

If you want to take away greenscreen footage then you really need the benefit of DVCAMPRO50 which has double the colour value and half the compression.

Original question, green or blue? Doesn't matter. Just don't use white, you'll key through their teeth.

[This message has been edited by RichardB (edited 30 January 2004).]

adgroberts
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Joined: Aug 22 2001

One little problem I found is eye colour. mine are blue and using a blue screen and chroma/colour key will remove the background and also the iris, looks a bit spooky actually. I suppose if you are using a lot of very close work eye colour of the "actor" becomes an important consideration. I find a green screen (made out of one of my wifes' unwearable dresses) is ok.
Regards
Tony Roberts

adgroberts