public static GradientVector[,] SuppressMaximums(this GradientVector[,] vecs)
{
GradientVector[,] res = new GradientVector[vecs.GetLength(0), vecs.GetLength(1)];
for (int y = 1; y < vecs.GetLength(0) - 1; y++)
{
for (int x = 1; x < vecs.GetLength(1) - 1; x++)
{
res[y, x].Angle = vecs[y, x].Angle;
switch (vecs[y, x].Angle)
{
case 0:
{
res[y, x].Length = vecs[y, x].Length >= vecs[y, x + 1].Length && vecs[y, x].Length >= vecs[y, x - 1].Length ? vecs[y, x].Length : 0;
break;
}
case 90:
{
res[y, x].Length = vecs[y, x].Length >= vecs[y + 1, x].Length && vecs[y, x].Length >= vecs[y - 1, x].Length ? vecs[y, x].Length : 0;
break;
}
case 45:
{
res[y, x].Length = vecs[y, x].Length >= vecs[y - 1, x - 1].Length && vecs[y, x].Length >= vecs[y + 1, x + 1].Length ? vecs[y, x].Length : 0;
break;
}
case -45:
{
res[y, x].Length = vecs[y, x].Length >= vecs[y + 1, x - 1].Length && vecs[y, x].Length >= vecs[y - 1, x + 1].Length ? vecs[y, x].Length : 0;
break;
}
}
}
}
return(res);
}
/// <summary>
/// Finds gradients and angle of gradients (Sobel);
/// </summary>
/// <param name="pic">Picture.</param>
/// <returns>Array of Gradients.</returns>
public static GradientVector[,] FindGradients(this Bitmap pic)
{
GradientVector[,] vecs = new GradientVector[pic.Height, pic.Width];
double[,] gYMask = new double[, ]
{
{ -1, -2, -1 },
{ 0, 0, 0 },
{ 1, 2, 1 }
};
double[,] gXMask = new double[, ]
{
{ -1, 0, 1 },
{ -2, 0, 2 },
{ -1, 0, 1 }
};
for (int x = 1; x < pic.Width - 1; x++)
{
for (int y = 1; y < pic.Height - 1; y++)
{
double gYRes = 0;
double gXRes = 0;
for (int i = -1; i < 2; i++)
{
for (int j = -1; j < 2; j++)
{
byte b = pic.GetPixel(x + j, y + i).R;
gXRes += pic.GetPixel(x + j, y + i).R *gXMask[i + 1, j + 1];
gYRes += pic.GetPixel(x + j, y + i).R *gYMask[i + 1, j + 1];
}
}
vecs[y, x].Length = Math.Sqrt(gXRes * gXRes + gYRes * gYRes);
vecs[y, x].Angle = GetCorrectAngle(Math.Atan(gYRes / gXRes));
}
}
return(vecs);
}