/// <summary>
/// Finds local extremum points in the contour.
/// </summary>
/// <param name="contour">A list of <see cref="IntPoint">
/// integer points</see> defining the contour.</param>
///
public List <IntPoint> FindPeaks(List <IntPoint> contour)
{
double[] map = new double[contour.Count];
for (int i = 0; i < contour.Count; i++)
{
IntPoint a, b, c;
int ai = Accord.Math.Tools.Mod(i + K, contour.Count);
int ci = Accord.Math.Tools.Mod(i - K, contour.Count);
a = contour[ai];
b = contour[i];
c = contour[ci];
// http://stackoverflow.com/questions/3486172/angle-between-3-points/3487062#3487062
//double angle = AForge.Math.Geometry.GeometryTools.GetAngleBetweenVectors(b, a, c);
DoublePoint ab = new DoublePoint(b.X - a.X, b.Y - a.Y);
DoublePoint cb = new DoublePoint(b.X - c.X, b.Y - c.Y);
double angba = System.Math.Atan2(ab.Y, ab.X);
double angbc = System.Math.Atan2(cb.Y, cb.X);
double rslt = angba - angbc;
if (rslt < 0)
{
rslt = 2 * Math.PI + rslt;
}
double rs = (rslt * 180) / Math.PI;
if (Theta.IsInside(rs))
{
map[i] = rs;
}
}
// Non-Minima Suppression
int r = Suppression;
List <IntPoint> peaks = new List <IntPoint>();
for (int i = 0; i < map.Length; i++)
{
double current = map[i];
if (current == 0)
{
continue;
}
bool isMinimum = true;
for (int j = -r; j < r && isMinimum; j++)
{
int index = Accord.Math.Tools.Mod(i + j, map.Length);
double candidate = map[index];
if (candidate == 0)
{
continue;
}
if (candidate < current)
{
isMinimum = false;
}
else
{
map[index] = 0;
}
}
if (isMinimum)
{
peaks.Add(contour[i]);
}
}
return(peaks);
}
