motion estimation and compensation for very low bitrate video coding

194 Chapter D. Complements to Chapter 5
Negative half-boundary Positive half-boundary
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Figure D.2: Order of use of tracking templates
/* define types of edge feature */
#define O 0 // bOundary
#define G 50 // Gap
#define S 100 // Self-intersection
#define I 150 // Intersection
#define C 200 // Closed loop
/* define the structure of a point on
a half-boundary */
typedef struct point* Point;
typedef struct point{
short contour; // contour number
short vpos; // vertical position in the image
short hpos; // horizontal position in the image
Point next; // pointer to the next point of the half-b.
Point previous; // pointer to the previous point of the half-b.
double angle; // for angle measurement
short href; // for extraction of highest curvature points
short feature; // type of point: O,G,S,I,C
};
/* define the structure of a half-boundarty */
typedef struct contour {
short number; // reference number of the half-boundary
short type; // type (P or N) of the half-boundary
Point first; // pointer to the first point of the contour
};
/* Routine that implements the corner detector based on the
description of Chapter 5, i.e. a modified version of Noble's
edge detector combined with Najman and Vaillant measure of
angles.
Typical parameters are given in the calling routine. */
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