The tar file ellin3.tar.Z contains the necessary code to process 
edge pixel data to produce a description based on lines or lines 
and ellipses. The programs included are as follows:

linknew.c	
    Reads in an image of edge points (either raw or in sunraster
    format) and builts a text file of linked edges i.e. a list
    of connected edge points per connected list of edge pixels.
    This assumes that something like the Marr-Hildreth or Canny
    edge detectors have been used that produce one-pixel wide
    edges. There are a number of options with this code:
        -i filename
        -o filename
        -w width
        -h height
        -t threshold
    The -i and -o allow specification of input and output images
    respectively, -w and -h specify the width and height of the
    raw image (512x512 default), and -t specifies a threshold
    that encodes long strong edges, long weak edges, short
    strong edges but not short weak edges so removes much
    clutter from the edge image. A typical value for the
    threshold is 1000.
    
lines.c
	Takes the edge file produced by linknew and, using Lowe's
    significance measure, fits straight lines to the edges.
    Produces a file of "super" data in which edh list of
    connected pixels is replaced by a list of lines with various
    parameters. There are a number of options:
        -i filename
        -o filename
        -I
        -3
        etc.
    The -I switch runs a second pass over the data to join
    together edges that are separated by the tree structure used
    (see paper). The -3 option saves intermediate pixel values
    in with the line data. These are required by the ellipse
    fitting stage to give enough points to overdetermine the
    ellipse fit.
    
ellin3.c
    Takes the super data file from lines and attempts to replace
    sequences of lines by ellipses. Again see paper for details
    of algorithm. Has similar options to lines.
    
xplotdata.c 
	Plots various feature files to an X window on the screen.
    Has many options including ability to plot multiple files
    overlayed, a feature file over an image, crosses at end
    points, ellipses in bold etc. Run orpgram with no options
    for details.
    
    Various other source code files are included in this tar
    file which are needed e.g. xplotlib.c which is a set of
    routines for simple use of X graphics for drawing. Used by
    xplotdata.c

Makefile
    Just to let you see what needs to be compiled and linked.

Files
    Shows the contents of the tar file.
    
See the paper:
    
    P. L. Rosin and G. A. W. West "Non-Parametric Segmentation 
    of Curves into Various Representations", accepted for IEEE
    PAMI, 1995.
    
G. A. W. West.
24-7-95