Path: utzoo!utgpu!news-server.csri.toronto.edu!mailrus!bbn.com!cosell
From: cosell@bbn.com (Bernie Cosell)
Newsgroups: comp.lang.postscript
Subject: Re: How to super-impose images ?
Message-ID: <58412@bbn.BBN.COM>
Date: 25 Jul 90 08:51:41 GMT
References: <31377@eerie.acsu.Buffalo.EDU> <1424@chinacat.Unicom.COM>
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woody@chinacat.Unicom.COM (Woody Baker @ Eagle Signal) writes:


}Adobe uses an opaque imaging model.  That is each layer obscures the
}layer underneath it.  There is no way to do AND, XOR, or OR operations.
}I think that was a mistake.  I can see the point, however, when you
}think about a FILM printer that does not use a memory map, but rather
}uses the exposed film to store the image.

Whatever the reason might be, this isn't it: since you can overlay previously
blackened pixels with white pixels, imaging directly to film cannot work.

}I think it should be allowed. ...

I agree.  MOre to the point, I think that the contents of the imaging area
should be generally available to be operated on.  There's no reason I can see
why things like finding the current bounding box or cutting and pasting the
image area shouldn't just work...

  /Bernie\