private static void Test1D()
{
// scaling factor is N
const int N = 16;
kiss_fft_cpx <float>[] timeDomain = new kiss_fft_cpx <float> [N];
kiss_fft_cpx <float>[] frequencyDomain = new kiss_fft_cpx <float> [N];
for (int i = 0; i < N; ++i)
{
timeDomain[i] = new kiss_fft_cpx <float>();
frequencyDomain[i] = new kiss_fft_cpx <float>();
}
for (int i = 0; i < N; i++)
{
timeDomain[i].r = 0.0f;
timeDomain[i].i = 0.0f;
}
TestFFT("Zeroes", timeDomain, frequencyDomain);
for (int i = 0; i < N; i++)
{
timeDomain[i].r = 1.0f;
timeDomain[i].i = 0.0f;
}
TestFFT("Ones", timeDomain, frequencyDomain);
for (int i = 0; i < N; i++)
{
timeDomain[i].r = (float)Math.Sin(2.0f * Math.PI * 4.0f * i / N);
timeDomain[i].i = 0.0f;
}
TestFFT("SineWave", timeDomain, frequencyDomain);
for (int i = 0; i < N; i++)
{
timeDomain[i].r = (float)Math.Cos(2.0f * Math.PI * 4.0f * i / N);
timeDomain[i].i = 0.0f;
}
TestFFT("CosineWave", timeDomain, frequencyDomain);
for (int i = 0; i < N; i++)
{
timeDomain[i].r = 1.0f + (float)Math.Sin(4.0f * 2.0f * Math.PI * i / N) + (float)Math.Sin(6.0f * 2.0f * Math.PI * i / N);
timeDomain[i].i = 0;
}
TestFFT("sin(4x)+sin(6x)", timeDomain, frequencyDomain);
}
private static void Test1D()
{
// scaling factor is N
const int N = 16;
kiss_fft_cpx<float>[] timeDomain = new kiss_fft_cpx<float>[N];
kiss_fft_cpx<float>[] frequencyDomain = new kiss_fft_cpx<float>[N];
for (int i = 0; i < N; ++i)
{
timeDomain[i] = new kiss_fft_cpx<float>();
frequencyDomain[i] = new kiss_fft_cpx<float>();
}
for (int i = 0; i < N; i++)
{
timeDomain[i].r = 0.0f;
timeDomain[i].i = 0.0f;
}
TestFFT("Zeroes", timeDomain, frequencyDomain);
for (int i = 0; i < N; i++)
{
timeDomain[i].r = 1.0f;
timeDomain[i].i = 0.0f;
}
TestFFT("Ones", timeDomain, frequencyDomain);
for (int i = 0; i < N; i++)
{
timeDomain[i].r = (float) Math.Sin(2.0f * Math.PI * 4.0f * i / N);
timeDomain[i].i = 0.0f;
}
TestFFT("SineWave", timeDomain, frequencyDomain);
for (int i = 0; i < N; i++)
{
timeDomain[i].r = (float) Math.Cos(2.0f * Math.PI * 4.0f * i / N);
timeDomain[i].i = 0.0f;
}
TestFFT("CosineWave", timeDomain, frequencyDomain);
for (int i = 0; i < N; i++)
{
timeDomain[i].r = 1.0f + (float) Math.Sin(4.0f * 2.0f * Math.PI * i / N) + (float) Math.Sin(6.0f * 2.0f * Math.PI * i / N);
timeDomain[i].i = 0;
}
TestFFT("sin(4x)+sin(6x)", timeDomain, frequencyDomain);
}
private static void TestFFT(string title, kiss_fft_cpx <float>[] timeDomain, kiss_fft_cpx <float>[] frequencyDomain)
{
System.Console.WriteLine(title);
{ // FFT
KissFFT <float> kissFft = new KissFFT <float>(timeDomain.Length, false, new FloatArithmetic());
kissFft.kiss_fft(new Array <kiss_fft_cpx <float> >(timeDomain), new Array <kiss_fft_cpx <float> >(frequencyDomain));
for (int i = 0; i < frequencyDomain.Length; ++i)
{
frequencyDomain[i].r /= (float)frequencyDomain.Length;
frequencyDomain[i].i /= (float)frequencyDomain.Length;
}
System.Console.Write("Offset = {0} + {1} * i\n", frequencyDomain[0].r, frequencyDomain[0].i);
for (int i = 1; i < frequencyDomain.Length / 2 + 1; ++i)
{
System.Console.Write("f({0}): {1} + {2} * i, ", i, frequencyDomain[i].r * 2.0f, frequencyDomain[i].i * 2.0f);
PrintEuler(frequencyDomain[i].r * 2.0f, frequencyDomain[i].i * 2.0f);
System.Console.WriteLine();
}
}
{ // inverse FFT
kiss_fft_cpx <float>[] inverted = new kiss_fft_cpx <float> [frequencyDomain.Length];
KissFFT <float> kissFft = new KissFFT <float>(frequencyDomain.Length, true, new FloatArithmetic());
kissFft.kiss_fft(new Array <kiss_fft_cpx <float> >(frequencyDomain), new Array <kiss_fft_cpx <float> >(inverted));
for (int i = 0; i < frequencyDomain.Length; ++i)
{
const float treshold = 0.00001f;
if (!(Math.Abs(timeDomain[i].r - inverted[i].r) < treshold && Math.Abs(timeDomain[i].i - inverted[i].i) < treshold))
{
System.Console.Write("{0} ({1}, {2}) != ({3}, {4})\n", i, timeDomain[i].r, timeDomain[i].i, inverted[i].r, inverted[i].i);
}
}
System.Console.WriteLine();
}
}
private static void TestFFT(string title, kiss_fft_cpx<float>[] timeDomain, kiss_fft_cpx<float>[] frequencyDomain)
{
System.Console.WriteLine(title);
{ // FFT
KissFFT<float> kissFft = new KissFFT<float>(timeDomain.Length, false, new FloatArithmetic());
kissFft.kiss_fft(new Array<kiss_fft_cpx<float>>(timeDomain), new Array<kiss_fft_cpx<float>>(frequencyDomain));
for (int i = 0; i < frequencyDomain.Length; ++i)
{
frequencyDomain[i].r /= (float) frequencyDomain.Length;
frequencyDomain[i].i /= (float) frequencyDomain.Length;
}
System.Console.Write("Offset = {0} + {1} * i\n", frequencyDomain[0].r, frequencyDomain[0].i);
for (int i = 1; i < frequencyDomain.Length / 2 + 1; ++i)
{
System.Console.Write("f({0}): {1} + {2} * i, ", i, frequencyDomain[i].r * 2.0f, frequencyDomain[i].i * 2.0f);
PrintEuler(frequencyDomain[i].r * 2.0f, frequencyDomain[i].i * 2.0f);
System.Console.WriteLine();
}
}
{ // inverse FFT
kiss_fft_cpx<float>[] inverted = new kiss_fft_cpx<float>[frequencyDomain.Length];
KissFFT<float> kissFft = new KissFFT<float>(frequencyDomain.Length, true, new FloatArithmetic());
kissFft.kiss_fft(new Array<kiss_fft_cpx<float>>(frequencyDomain), new Array<kiss_fft_cpx<float>>(inverted));
for (int i = 0; i < frequencyDomain.Length; ++i)
{
const float treshold = 0.00001f;
if (!(Math.Abs(timeDomain[i].r - inverted[i].r) < treshold && Math.Abs(timeDomain[i].i - inverted[i].i) < treshold))
{
System.Console.Write("{0} ({1}, {2}) != ({3}, {4})\n", i, timeDomain[i].r, timeDomain[i].i, inverted[i].r, inverted[i].i);
}
}
System.Console.WriteLine();
}
}
private static void Filter2D(Bitmap input, ref Bitmap output, FilterFunction filterFunction)
{
int[] dims = new int[2] {
input.Width, input.Height
};
kiss_fft_cpx <float>[] timeDomain = new kiss_fft_cpx <float> [input.Width * input.Height];
kiss_fft_cpx <float>[] frequencyDomain = new kiss_fft_cpx <float> [input.Width * input.Height];
for (int i = 0; i < input.Width * input.Height; ++i)
{
timeDomain[i] = new kiss_fft_cpx <float>();
frequencyDomain[i] = new kiss_fft_cpx <float>();
}
{ // FFT
for (int x = 0; x < input.Width; ++x)
{
for (int y = 0; y < input.Height; ++y)
{
timeDomain[y * input.Width + x].r = input.GetPixel(x, y).R;
timeDomain[y * input.Width + x].i = 0.0f;
}
}
KissFFTnd <float> kissFftnd = new KissFFTnd <float>(dims, 2, false, new FloatArithmetic());
kissFftnd.kiss_fftnd(new Array <kiss_fft_cpx <float> >(timeDomain), new Array <kiss_fft_cpx <float> >(frequencyDomain));
for (int i = 0; i < input.Width * input.Height; ++i)
{
frequencyDomain[i].r /= input.Width * input.Height;
frequencyDomain[i].i /= input.Width * input.Height;
}
}
{ // filter
for (int x = 0; x < input.Width; ++x)
{
for (int y = 0; y < input.Height; ++y)
{
float q = filterFunction(x, y, input.Width, input.Height);
frequencyDomain[y * input.Width + x].r *= q;
frequencyDomain[y * input.Width + x].i *= q;
}
}
}
{ // IFFT
output = new Bitmap(input.Width, input.Height);
KissFFTnd <float> kissFftnd = new KissFFTnd <float>(dims, 2, true, new FloatArithmetic());
kissFftnd.kiss_fftnd(new Array <kiss_fft_cpx <float> >(frequencyDomain), new Array <kiss_fft_cpx <float> >(timeDomain));
for (int x = 0; x < input.Width; ++x)
{
for (int y = 0; y < input.Height; ++y)
{
int intensity = (int)timeDomain[y * input.Width + x].r;
intensity = Math.Min(255, Math.Max(0, intensity));
output.SetPixel(x, y, Color.FromArgb(intensity, intensity, intensity));
}
}
}
}
private static void Filter2D(Bitmap input, ref Bitmap output, FilterFunction filterFunction)
{
int[] dims = new int[2] { input.Width, input.Height };
kiss_fft_cpx<float>[] timeDomain = new kiss_fft_cpx<float>[input.Width * input.Height];
kiss_fft_cpx<float>[] frequencyDomain = new kiss_fft_cpx<float>[input.Width * input.Height];
for (int i = 0; i < input.Width * input.Height; ++i)
{
timeDomain[i] = new kiss_fft_cpx<float>();
frequencyDomain[i] = new kiss_fft_cpx<float>();
}
{ // FFT
for (int x = 0; x < input.Width; ++x)
{
for (int y = 0; y < input.Height; ++y)
{
timeDomain[y * input.Width + x].r = input.GetPixel(x, y).R;
timeDomain[y * input.Width + x].i = 0.0f;
}
}
KissFFTnd<float> kissFftnd = new KissFFTnd<float>(dims, 2, false, new FloatArithmetic());
kissFftnd.kiss_fftnd(new Array<kiss_fft_cpx<float>>(timeDomain), new Array<kiss_fft_cpx<float>>(frequencyDomain));
for (int i = 0; i < input.Width * input.Height; ++i)
{
frequencyDomain[i].r /= input.Width * input.Height;
frequencyDomain[i].i /= input.Width * input.Height;
}
}
{ // filter
for (int x = 0; x < input.Width; ++x)
{
for (int y = 0; y < input.Height; ++y)
{
float q = filterFunction(x, y, input.Width, input.Height);
frequencyDomain[y * input.Width + x].r *= q;
frequencyDomain[y * input.Width + x].i *= q;
}
}
}
{ // IFFT
output = new Bitmap(input.Width, input.Height);
KissFFTnd<float> kissFftnd = new KissFFTnd<float>(dims, 2, true, new FloatArithmetic());
kissFftnd.kiss_fftnd(new Array<kiss_fft_cpx<float>>(frequencyDomain), new Array<kiss_fft_cpx<float>>(timeDomain));
for (int x = 0; x < input.Width; ++x)
{
for (int y = 0; y < input.Height; ++y)
{
int intensity = (int) timeDomain[y * input.Width + x].r;
intensity = Math.Min(255, Math.Max(0, intensity));
output.SetPixel(x, y, Color.FromArgb(intensity, intensity, intensity));
}
}
}
}