public static double[] AverageRGB(Bitmap img, Window w)
{
double[] colors = new double[3];
for(int x = w.StartX; x < w.EndX; x++) for(int y = w.StartY; y < w.EndY; y++)
{
Color pixval = img.GetPixel(x,y);
colors[0] += pixval.R;
colors[1] += pixval.G;
colors[2] += pixval.B;
}
double multfactor = 1/((double)w.Area);
for(int i = 0; i < 3; i++) colors[i] *= multfactor;
return colors;
}
/// <summary>
/// Gets the histogram of oriented gradients corresponding to a particular window in the specified bmp.
/// </summary>
/// <returns>
/// The hogs.
/// </returns>
/// <param name='bmp'>
/// The bitmap.
/// </param>
/// <param name='w'>
/// The window over which to make the histogram.
/// </param>
public double[] GetHogs(Bitmap bmp, Window w)
{
DenseVector[,] grads = GradientMaker.GetGradients(bmp);
double[] hogs = new double[NumOrientations];
for(int x = w.StartX; x < w.EndX; x++) for(int y = w.StartY; y < w.EndY; y++)
{
DenseVector g = grads[x,y];
//PREPARE FOR HACK
double angle = Math.Atan2 (g[1],g[0]);
if(angle < 0) angle += 2*Math.PI;
int orientation = (int)Math.Floor((((double)NumOrientations)/(2*Math.PI))*angle);
orientation = orientation % NumOrientations; //Hack moar--mitigated now. Still bad.
double magnitude = g.Norm(2);
hogs[orientation] += magnitude;
}
return hogs;
}
/// <summary>
/// Gets the histogram of oriented gradients corresponding to a particular window in the specified bmp,
/// and smoothes it.
/// </summary>
/// <returns>
/// The hogs.
/// </returns>
/// <param name='bmp'>
/// The bitmap.
/// </param>
/// <param name='w'>
/// The window over which to make the histogram.
/// </param>
public double[] GetSmoothedHogs(Bitmap bmp, Window w)
{
if(bmp == null) throw new ArgumentNullException("bmp", "Specify a non-null argument.");
if(w == null) throw new ArgumentNullException("w", "Specify a non-null argument.");
double[] hogs = GetHogs(bmp, w);
double[] shogs = new double[NumOrientations];
for(int i = 0; i < NumOrientations; i++)
{
double numerator = 0;
double denom = 0;
int b = Convert.ToInt32(Math.Ceiling(SMOOTHING_KERNEL_BANDWIDTH));
for(int j = i - Math.Min(b, NumOrientations/2); j <= i + Math.Min(b, NumOrientations/2); j++)
{
// As long as the kernel bandwidth is not larger than NUM_ORIENTATIONS/2, we don't
// count directions multiple times.
double coeff = SmoothingKernel(((double)(i-j))/SMOOTHING_KERNEL_BANDWIDTH);
denom += coeff;
numerator += coeff*hogs[(j+NumOrientations)%NumOrientations];
}
shogs[i] = numerator/denom;
if(denom == 0) throw new NotFiniteNumberException();
//Dealing with area mismatches
shogs[i] *= 4096;
shogs[i] /= w.Area;
}
return shogs;
}
