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Posted by Bill Fright on 10/05/94 11:37
Tech Geek wrote:
> Hi! I've already sent this message out to rec.video.professional, but
> nobody was able to help me . . . hopefully somebody here could!
> Anything is much appreciated:
>
> I am the lead technician at my school in Ontario, Canada. Every morning
> we have "announcements" during which students announce school news and
> the principal speaks for a couple of minutes. We have been doing it
> the same way for years, using an old Panasonic WJ-MX20 as our video
> mixer, and a cheap Radio Shack board as our sound mixer (the
> announcements are broadcast live through all the TV's in the
> classrooms).
>
> Anyway, the other day I decided I would try to use the Chroma Key
> effect built into the Video Mixer (WJ-MX20). I understood that a green
> or blue screen works best, but at the time I only had a simple white
> canvas. As far as I'm concerned the white wouldn't do a good job as
> skin pigments are mainly white, along with clothes, etc. However, I
> wanted to make sure the effect worked at least decently and in the
> right way before I painted the canvas green.
>
> I checked with the instruction manual (availible online) and followed
> the directions very carefully. I put a student in front of the canvas,
> put the camera on the student and canvas background, selected the
> camera on the B-BUS (it's a two bus board (A and B)) as told by the
> directions, and put the picture of a mountain scene on A-BUS (coming
> from the computer). To activate green screen, you use a little curser
> on the preview television hooked to mixer to select the background
> which you will be "changing". I did as the instructions said, pushed
> enter, and it did the opposite of what I wanted! It made most of the
> student mountain-designed, and the white canvas . . . white. I tried
> positioning the curser over the student hoping that it might work and
> it did the same thing!
>
> If anyone out there has any idea on what to do, I would appreciate it
> GREATLY. Thank you very much!
>
> Alexander Tingle
>
this is a pretty cheap mixer so you have to help it by giving it an
optimim physical set up. I think your post above said you were testing
over white. You also mentioned this would not work and you were right.
First thing I'd do for a test is go to a video rental house and buy some
green seamless. Or go an art store and get the green.
Light the subject and background at a 1:1 ratio (the same light level).
Try your cursor setup.
bill
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