我试图实现以下FFT滤波器核心：
（注：此公式下方应有两个平方符号）
源代码：
（注：此公式下方应有两个平方符号）源代码：
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
Bitmap image = DataConverter2d.ReadGray(StandardImage.LenaGray);
Array2d<double> dImage = DataConverter2d.ToDouble(image);
int newWidth = Tools.ToNextPowerOfTwo(dImage.Width) * 2;
int newHeight = Tools.ToNextPowerOfTwo(dImage.Height) * 2;
double n = 6;
double f0 = 0.5;
double theta = 60;
double a = 0.4;
Array2d<Complex> kernel2d = CustomFft(newWidth, newHeight, n, f0, theta, a);
dImage.PadTo(newWidth, newHeight);
Array2d<Complex> cImage = DataConverter2d.ToComplex(dImage);
Array2d<Complex> fImage = FourierTransform.ForwardFft(cImage);
// FFT convolution .................................................
Array2d<Complex> fOutput = new Array2d<Complex>(newWidth, newHeight);
for (int x = 0; x < newWidth; x++)
{
for (int y = 0; y < newHeight; y++)
{
fOutput[x, y] = fImage[x, y] * kernel2d[x, y];
}
}
Array2d<Complex> cOutput = FourierTransform.InverseFft(fOutput);
Array2d<double> dOutput = Rescale2d.Rescale(DataConverter2d.ToDouble(cOutput));
dOutput.CropBy((newWidth - image.Width) / 2, (newHeight - image.Height) / 2);
Bitmap output = DataConverter2d.ToBitmap(dOutput, image.PixelFormat);
Array2d<Complex> cKernel = FourierTransform.InverseFft(kernel2d);
cKernel = FourierTransform.RemoveFFTShift(cKernel);
Array2d<double> dKernel = DataConverter2d.ToDouble(cKernel);
Array2d<double> dLimitedKernel = Rescale2d.Limit(dKernel);
Bitmap kernel = DataConverter2d.ToBitmap(dLimitedKernel, image.PixelFormat);
pictureBox1.Image = image;
pictureBox2.Image = kernel;
pictureBox3.Image = output;
}
private double Basic(double u, double v, double n, double f0, double rad, double a, double b)
{
double ua = u + f0 * Math.Cos(rad);
double va = v + f0 * Math.Sin(rad);
double ut = ua * Math.Cos(rad) + va * Math.Sin(rad);
double vt = (-1) * ua * Math.Sin(rad) + va * Math.Cos(rad);
double p = ut/a;
double q = vt/b;
double sqrt = Math.Sqrt(p*p + q*q);
return 1.0 / (1.0+ 0.414 * Math.Pow(sqrt, 2*n));
}
private double Custom(double u, double v, double n, double f0, double theta, double a)
{
double rad1 = (Math.PI / 180) * (90-theta);
double rad2 = rad1 + Math.PI;
double b = (a / 5.0) / (2*n);
double ka = Basic(u, v, n, f0, rad1, a, b);
double kb = Basic(u, v, n, f0, rad2, a, b);
return Math.Max(ka, kb);
}
private Array2d<Complex> CustomFft(double sizeX, double sizeY, double n, double f0, double theta, double a)
{
double halfX = sizeX / 2;
double halfY = sizeY / 2;
Array2d<Complex> kernel = new Array2d<Complex>((int)sizeX, (int)sizeY);
for (double y = 0; y < sizeY; y++)
{
double v = y / sizeY;
for (double x = 0; x < sizeX; x++)
{
double u = x / sizeX;
double kw = Custom(u, v, n, f0, theta, a);
kernel[(int)x, (int)y] = new Complex(kw, 0);
}
}
return kernel;
}
}
此时只需专注于算法和公式。
输出
这个滤镜的问题是，它只能在0-90度之间旋转，并且在该范围之外无法工作。
如何使其在0-360度之间旋转？