Feature Extraction and Image Processing

Low-level feature extraction (including edge detection) 135

x(t) = a

x

+ b

x

t + c

x

t

2

(4.41)

y(t) = a

y

+ b

y

t + c

y

t

2

A simplification can be obtained by considering that v(0) is the point where we want to

evaluate curvature. Thus, the lower order values of the polynomial are known and are given

by the pixel’s co-ordinates. That is, a

x

= x(0) and a

y

= y(0). If the parameter t enumerates

the points in the sequence, then this means that the pixels must be indexed by negative and

positive values of t in the trailing and leading curve segments, respectively. That is, we

need to index a sequence of pixels relative to the pixel where we are computing curvature. ...