Input: - Flexible template (T)
- of contours in the image (C)
Output: - Set of potentially matching contours (M)
- Set of starting points for each ith matching contour (Si)
- Set of combinations of feature points for each mi € M and sij € Si (Fij)
i ← 0% reset number of potentially matching contours
for each ck € C do
% create set Pk = (pk: pk is feature point of kth contour}
q ← get number of points belonging to ck
for n = 1..q do
crvkn ← compute curvature for nth point of ck
drvkn ← compute derivative of curvature for nth point of ck
end for
l ← 0% reset number of feature points for ck
for n = 1..q do
if crvkn is local extremum then
l ← l + 1
type(pkl) ← 1% create feature point of type 1
x(pkl),y(pkl) ← get coordinates of nth point of ck
end if
if drvkn is local extremum then
l ← l + 1
type(pkl) ← 1% create feature point of type 2
x(pkl),y(pkl) ← get coordinates of nth point of ck
end if
end for
% Attempts to superimpose template T on contour ck
i ← i + 1% increase number of potentially matching contours
mi ← ck % assume ck as ith matching contour mi € M
j ← 0% reset number of starting points for mi
for each pkl € Pk do
j ← j + 1% increase starting point number
sij ← pkl % assume pkl as jth starting point sij € Si
FPK ← create feature point combinations for jth starting point
e ← 0% reset number of feature point combinations
for u = 1..|FPK| do
e ← e + 1% increase number of matching combinations
fije ← fpku % assume fpku € FPK as eth combination fije € Fij
match ← true % auxiliary logical variable
for each template statement ty € T do
if conditions imposed by ty are not fulfilled by fije then
match ← false
end if
end for
if not match then
e ← e − 1
delete e th feature point combination f kne
end if
end for
if e = 0 then
j ← j − 1% decrease starting point number
end if
end for
if j = 0 then
i ← i − 1% decrease matching contour number
end if
end for
