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Subject: RE: YET ANOTHER SUGGESTION N
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Date: Tue, 25 Apr 95 00:29:01 PDT
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Mark Thompson says:
>alan.chan@oubbs.telecom.uoknor.edu asks:
>> Would it be possible to
>> look at the blue values from the RGB files and turn it into an 8-bit
>> transparency?
>
>Its actually a much more complex problem than it seems and this simple
>approach will not do it effectively. Consider that your blue background
>is neither a pure full intensity blue, nor is it perfectly uniform. Yet
>you want it to matte out completely while still preserving things like
>shadows, smoke, fine detail, or translucent surfaces. Pretty tricky stuff.
Just to shoot this down totally, Alan, just consider, say,
cyan or magenta: both have blue components, but obviously you'd
not want to key them out.
It's more like, isolate a particular >>vector<< on the vectorscope,
and build a transparency mask from that, mathematically (i.e.,
without hardware).
BTW, the keying capabilities in After Effects (Mac only, <sob!>) are