~{A;F8STANFORD ARTIFICIAL INTELLIGENCE LABORATORY	           JUNE 1973.
MEMO AIM-199

COMPUTER SCIENCE DEPARTMENT REPORT
NO. CS-362




                 {IMAGE  CONTOURING  AND  COMPARING}


                          Bruce G. Baumgart


ABSTRACT:

	A contour  image representation  is stated  and an  algorithm
for  converting  a   set  of  digital  television  images  into  this
representation is explained.   The algorithm consists of five  steps:
digital  image  thresholding,    binary image  contouring,    polygon
nesting,     polygon   smoothing,     and  polygon  comparing.     An
implementation of  the algorithm  is the  main routine  of a  program
called CRE;  auxiliary routines provide cart and  turn table control,
TV camera  input,   image  display,    and xerox  printer  output.  A
serendip application  of CRE to  type font contruction  is explained.
Details  about the intended application  of CRE to  the perception of
physical objects will appear in sequels to this paper.



	CONTENTS:

		     Introduction.

		  I. The CRE data structure.

		 II. The CRE algorithm.

		III. Using CRE.

		 IV. Using TVFONT.

		     Postscripts.



This  research was supported by the Advanced Research Projects Agency
   of the Office of the Secretary of Defense under contract SD-183.