  The paper presents two edge grouping algorithms for finding a closed contour
starting from a particular edge point and enclosing a fixation point. Both
algorithms search a shortest simple cycle in \textit{an angularly ordered
graph} derived from an edge image where a vertex is an end point of a contour
fragment and an undirected arc is drawn between a pair of end-points whose
visual angle from the fixation point is less than a threshold value, which is
set to $\pi/2$ in our experiments. The first algorithm restricts the search
space by disregarding arcs that cross the line extending from the fixation
point to the starting point. The second algorithm improves the solution of the
first algorithm in a greedy manner. The algorithms were tested with a large
number of natural images with manually placed fixation and starting points. The
results are promising.
