// this function does nothing, but without it, when first plan is created using real images, for some parameters
// the first output image is empty and the rest is fine, so it's better to create here this no-use plan just
// to be sure that everything works
private void PreparePlan(int w, int h)
{
double[] d1 = new double[w * h * 2];
double[] d2 = new double[w * h * 2];
IntPtr plan = FFTW.PlanDFT2D(h, w, d1, d2, FFTW.Direction.Forward, 0);
FFTW.DestroyPlan(plan);
}
private IImage FFT(IImage img)
{
double[] datain = new double[img.W * img.H * 2];
double[] dataout = new double[img.W * img.H * 2];
for (int y = 0; y < img.H; y++)
{
for (int x = 0; x < img.W; x++)
{
datain[(x + y * img.W) * 2] = (byte)img[x, y];
datain[(x + y * img.W) * 2 + 1] = 0;
}
}
IntPtr plan = FFTW.PlanDFT2D(img.H, img.W, datain, dataout, FFTW.Direction.Forward, 0);
FFTW.Execute(plan);
FFTW.DestroyPlan(plan);
IImage ret = new IImage(BPP.Float, img.W, img.H);
for (int y = 0; y < img.H; y++)
{
for (int x = 0; x < img.W; x++)
{
double re = dataout[(x + y * img.W) * 2];
double im = dataout[(x + y * img.W) * 2 + 1];
double val = Math.Sqrt(re * re + im * im);
int newx = (x + img.W / 2) % img.W;
int newy = (y + img.H / 2) % img.H;
ret[newx, newy] = (float)val / 255f;
}
}
if (zero)
{
ret[img.W / 2, img.H / 2] = 0f;
}
return(ret);
}