/// <summary>
/// Mean shift algorithm
/// </summary>
///
private CentralMoments meanShift(UnmanagedImage frame)
{
// Variable initialization
int width = frame.Width;
int height = frame.Height;
// (assume all frames have equal dimensions)
if (map == null)
{
map = new float[height, width];
}
// Grab the current region of interest in the current frame
Rectangle roi = conservative ? searchWindow : new Rectangle(0, 0, frame.Width, frame.Height);
// Compute the histogram for the current frame
float[] currentHistogram = createHistogram(frame, roi);
// Use the previous histogram to compute a ratio histogram (storing in current)
computeHistogramRatio(originalHistogram, currentHistogram, currentHistogram);
// Compute the back-projection map using the ratio histogram
lock (sync) generateBackprojectionMap(frame, currentHistogram);
RawMoments moments = new RawMoments(1);
// Mean shift with fixed number of iterations
for (int i = 0; i < MAX_ITERATIONS - 1; i++)
{
// Locate first order moments
moments.Compute(map, searchWindow);
// Shift the mean (centroid)
searchWindow.X += (int)(moments.CenterX - searchWindow.Width / 2f);
searchWindow.Y += (int)(moments.CenterY - searchWindow.Height / 2f);
}
// Locate second order moments and perform final shift
moments.Order = 2; moments.Compute(map, searchWindow);
searchWindow.X += (int)(moments.CenterX - searchWindow.Width / 2f);
searchWindow.Y += (int)(moments.CenterY - searchWindow.Height / 2f);
// Keep the search window inside the image
searchWindow.X = Math.Max(0, Math.Min(searchWindow.X, width));
searchWindow.Y = Math.Max(0, Math.Min(searchWindow.Y, height));
return(new CentralMoments(moments)); // moments to be used by Camshift
}
private static Rectangle process(Gray <byte>[,] probabilityMap, Rectangle roi, TermCriteria termCriteria, out CentralMoments centralMoments)
{
Rectangle imageArea = new Rectangle(0, 0, probabilityMap.Width(), probabilityMap.Height());
Rectangle searchWindow = roi;
RawMoments moments = new RawMoments(order: 1);
// Mean shift with fixed number of iterations
int i = 0;
double shift = Byte.MaxValue;
while (termCriteria.ShouldTerminate(i, shift) == false && !searchWindow.IsEmptyArea())
{
// Locate first order moments
moments.Compute(probabilityMap, searchWindow);
int shiftX = (int)(moments.CenterX - searchWindow.Width / 2f);
int shiftY = (int)(moments.CenterY - searchWindow.Height / 2f);
// Shift the mean (centroid)
searchWindow.X += shiftX;
searchWindow.Y += shiftY;
// Keep the search window inside the image
searchWindow.Intersect(imageArea);
shift = System.Math.Abs((double)shiftX) + System.Math.Abs((double)shiftY); //for term criteria only
i++;
}
if (searchWindow.IsEmptyArea() == false)
{
// Locate second order moments and perform final shift
moments.Order = 2;
moments.Compute(probabilityMap, searchWindow);
searchWindow.X += (int)(moments.CenterX - searchWindow.Width / 2f);
searchWindow.Y += (int)(moments.CenterY - searchWindow.Height / 2f);
// Keep the search window inside the image
searchWindow.Intersect(imageArea);
}
centralMoments = new CentralMoments(moments); // moments to be used by camshift
return(searchWindow);
}
internal override void Compute(IImage image)
{
RawMoments raw = new RawMoments(Order);
raw.Compute(image);
CentralMoments center = new CentralMoments(raw);
this.Compute(center);
}
/// <summary>
/// Computes moments for the provided image.
/// </summary>
/// <param name="image">Image.</param>
/// <param name="area">Area</param>
public void Compute(Gray <float>[,] image, Rectangle area)
{
RawMoments raw = new RawMoments(Order);
raw.Compute(image, area);
CentralMoments center = new CentralMoments(raw);
this.Compute(center);
}
internal override void Compute(IImage image)
{
RawMoments raw = new RawMoments(Order);
raw.Compute(image);
CentralMoments center = new CentralMoments(raw);
this.Compute(center);
}