private static double[,,] GenerateXSignature(int[,] normalizedImage)
{
var lro = OrientationFieldGenerator.GenerateLocalRidgeOrientation(normalizedImage);
int maxY = lro.GetLength(0);
int maxX = lro.GetLength(1);
var result = new double[maxY, maxX, L];
for (int i = 0; i < maxY; i++)
{
for (int j = 0; j < maxX; j++)
{
for (int k = 0; k < L; k++)
{
result[i, j, k] = 0;
for (int d = 0; d < W; d++)
{
int u = Convert.ToInt32(i + (d - W / 2) * Math.Cos(lro[i, j]) + (k - L / 2) * Math.Sin(lro[i, j]));
int v = Convert.ToInt32(j + (d - W / 2) * Math.Cos(lro[i, j]) + (L / 2 - k) * Math.Sin(lro[i, j]));
if (u >= 0 && u < maxY && v >= 0 && v < maxX)
{
result[i, j, k] += normalizedImage[u, v];
}
else
{
result[i, j, k] = -1;
}
}
if (result[i, j, k] != -1)
{
result[i, j, k] /= (double)W;
}
}
}
}
return(result);
}
public static double[,] GenerateInterpolatedFrequency(int[,] image)
{
var freq = GenerateFrequency(image);
int maxY = freq.GetLength(0);
int maxX = freq.GetLength(1);
var kernel = OrientationFieldGenerator.GenerateGaussianKernel(3);
int size = kernel.GetLength(0) / 2;
int w = 7;//kernel.GetLength(0);
bool flag = true;
Func <double, double> m = x => (x <= 0 ? 0 : x);
Func <double, double> b = x => (x <= 0 ? 0 : 1);
while (flag)
{
for (int i = 0; i < maxY; i++)
{
for (int j = 0; j < maxX; j++)
{
if (freq[i, j] == -1)
{
// Interpolation
double numerator = 0;
double denominator = 0;
for (int u = -w / 2; u <= w / 2; u++)
{
for (int v = -w / 2; v <= w / 2; v++)
{
int y = i - u * w;
int x = j - v * w;
if (x >= 0 && x < maxX && y >= 0 && y < maxY)
{
numerator += kernel[u + size, v + size] * m(freq[y, x]);
denominator += kernel[u + size, v + size] * b(freq[y, x] + 1);
}
}
}
freq[i, j] = (denominator == 0 ? -1 : numerator / denominator);
}
}
}
// Check if there exist any -1 frequency
flag = false;
for (int i = 0; i < maxY; i++)
{
for (int j = 0; j < maxX; j++)
{
if (freq[i, j] == -1)
{
flag = true;
}
}
}
}
var result = new double[maxY, maxX];
for (int i = 0; i < maxY; i++)
{
for (int j = 0; j < maxX; j++)
{
result[i, j] = 0;
for (int dy = -w / 2; dy <= w / 2; dy++)
{
for (int dx = -w / 2; dx <= w / 2; dx++)
{
int x = j + dx * w;
int y = i + dy * w;
if (x >= 0 && x < maxX && y >= 0 && y < maxY)
{
result[i, j] += freq[y, x] * kernel[dy + size, dx + size];
}
}
}
}
}
return(result);
}
