private static bool InterpolateFrequency(this double[,] frequencyMatrix, int filterSize, double sigma, int w)
{
bool needMoreInterpolationFlag = false;
int height = frequencyMatrix.GetLength(0);
int width = frequencyMatrix.GetLength(1);
for (int i = 0; i < height; i ++)
{
for (int j = 0; j < width; j ++)
{
if (frequencyMatrix[i, j] == -1.0)
{
var gaussian = new Filter(filterSize, sigma);
int center = filterSize/2; //filter is always a square.
int upperCenter = (filterSize & 1) == 0 ? center - 1 : center;
double numerator = 0;
double denominator = 0;
for (int u = -upperCenter; u <= center; u++)
{
for (int v = -upperCenter; v <= center; v++)
{
int indexX = i + u * w;
int indexY = j + v * w;
if (indexX < 0) indexX = 0;
if (indexX >= height) indexX = height - 1;
if (indexY < 0) indexY = 0;
if (indexY >= width) indexY = width - 1;
numerator += gaussian.Matrix[center - u, center - v]*Mu(frequencyMatrix[indexX, indexY]);
denominator += gaussian.Matrix[center - u, center - v]*Delta(frequencyMatrix[indexX, indexY] + 1);
}
}
frequencyMatrix[i, j] = numerator/denominator;
if ((frequencyMatrix[i, j] != frequencyMatrix[i, j]) || (frequencyMatrix[i, j] > 1.0/3.0) ||
(frequencyMatrix[i, j] < 0.04))
{
frequencyMatrix[i, j] = -1;
needMoreInterpolationFlag = true;
}
}
}
}
return needMoreInterpolationFlag;
}
private static double[,] FilterFrequencies(double[,] frequencyMatrix, int filterSize, double sigma, int w)
{
var result = new double[frequencyMatrix.GetLength(0), frequencyMatrix.GetLength(1)];
var lowPassFilter = new Filter(filterSize, sigma);
lowPassFilter.Normalize();
result = ConvolutionHelper.Convolve(frequencyMatrix, lowPassFilter.Matrix, w);
return result;
}
