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From: portuesi@tweezers.esd.sgi.com (Michael Portuesi)
Newsgroups: comp.graphics
Subject: Compositing Digital Images
Message-ID: 
Date: 17 Aug 89 12:04:32 GMT
Sender: news@odin.SGI.COM
Organization: Silicon Graphics, Inc., Mtn. View, CA
Lines: 26




I am looking for material on various methods used for compositing two
digital images.

I am aware of two methods for combining images. The first is the
Porter-Duff matte algebra, which uses an alpha map for each image
describing the opacity of each pixel in the image.  (Compositing
Digital Images, Computer Graphics, Vol. 18, No. 3, ACM, July 84).  The
second method I have seen is used by "Digital Darkroom", a Macintosh
image processing program.  It allows the user to selectively determine
which grey values in the source image will be "painted" onto the
target images, and what grey values in the image may be "painted"
upon.  The net effect is to allow the user to declare portions of
both images as stencils.

I am looking for other methods.  Pointers to published material or
short descriptions would be welcome.  E-mail responses are invited; I
will send summaries to interested parties.

				--M

--
Michael Portuesi	Silicon Graphics Computer Systems, Inc.
			portuesi@SGI.COM