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From: Jeric@cup.portal.com
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To: lightwave-l@netcom.com
Subject: RE: YET ANOTHER SUGGESTION N
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Date: Tue, 25 Apr 95 23:36:03 PDT
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Ernie Wright, reeling from illicit drug usage, writes:
>Mark Thompson:
>> 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.
>
>It doesn't strike me as being that hard. As a first try, translate the
>RGB into HSV (hue, saturation, value) and tag the pixels lying near some
>(bluish) H. If that doesn't work very well, try YUV or some other color
>space. There's likely to be SOME linear transformation that makes the
>matte color stick out like a sore thumb.
>
>I suspect this isn't discussed in the context of digital graphics much
^^^^^^^^^^^^^^^^^^^^^^^^^^
>because it's only a problem when live video is involved, and the analog
>approach for video has been working fine for three decades.
>
>- Ernie
>
Who are you, and what have you done with Ernie!???
Chroma keying is extremely powerful and useful in creating digital
traveling mattes in compositing operations. This includes
keying digitized image streams.
Also, I'd contest that "working fine", considering the amount of