/// <summary>
/// Two dimensional Fast Fourier Transform.
/// </summary>
/// <param name="width">Image width.</param>
/// <param name="height">Image height.</param>
/// <param name="stride">Image stride.</param>
/// <param name="data">Data to transform.</param>
/// <param name="direction">Transformation direction.</param>
///
/// <remarks><para><note>The method accepts <paramref name="data"/> array of 2<sup>n</sup> size
/// only in each dimension, where <b>n</b> may vary in the [1, 14] range. For example, 16x16 array
/// is valid, but 15x15 is not.</note></para></remarks>
///
/// <exception cref="ArgumentException">Incorrect data length.</exception>
///
public unsafe static void FFT2(ComplexF *data, int width, int height, int stride, Direction direction)
{
int k = height;
int n = width;
// check data size
if (
(!AForge.Math.Tools.IsPowerOf2(k)) ||
(!AForge.Math.Tools.IsPowerOf2(n)) ||
(k < minLength) || (k > maxLength) ||
(n < minLength) || (n > maxLength)
)
{
throw new ArgumentException("Incorrect data length.");
}
// process rows
ComplexF *dataPtr = data; //get row
for (int i = 0; i < height; i++)
{
// transform it
FourierTransform.FFT(dataPtr, n, direction);
dataPtr += stride / sizeof(ComplexF);
}
// process columns
dataPtr = data; //get column
fixed(ComplexF *_col = new ComplexF[k])
{
ComplexF *col = _col;
for (int j = 0; j < height; j++)
{
// copy column
ComplexF *dataColPtr = &dataPtr[j];
for (int i = 0; i < k; i++)
{
col[i] = *dataColPtr;
dataColPtr += stride / sizeof(ComplexF);
}
// transform it
FourierTransform.FFT(col, k, direction);
// copy back
dataColPtr = &dataPtr[j];
for (int i = 0; i < k; i++)
{
*dataColPtr = col[i];
dataColPtr += stride / sizeof(ComplexF);
}
}
}
}
/// <summary>
/// Two dimensional Fast Fourier Transform.
/// </summary>
///
/// <param name="data">Data to transform.</param>
/// <param name="direction">Transformation direction.</param>
///
/// <remarks><para><note>The method accepts <paramref name="data"/> array of 2<sup>n</sup> size
/// only in each dimension, where <b>n</b> may vary in the [1, 14] range. For example, 16x16 array
/// is valid, but 15x15 is not.</note></para></remarks>
///
/// <exception cref="ArgumentException">Incorrect data length.</exception>
///
public static void FFT2(ComplexF[,] data, Direction direction)
{
int k = data.GetLength(0);
int n = data.GetLength(1);
// check data size
if (
(!Tools.IsPowerOf2(k)) ||
(!Tools.IsPowerOf2(n)) ||
(k < minLength) || (k > maxLength) ||
(n < minLength) || (n > maxLength)
)
{
throw new ArgumentException("Incorrect data length.");
}
// process rows
ComplexF[] row = new ComplexF[n];
for (int i = 0; i < k; i++)
{
// copy row
for (int j = 0; j < n; j++)
{
row[j] = data[i, j];
}
// transform it
FourierTransform.FFT(row, direction);
// copy back
for (int j = 0; j < n; j++)
{
data[i, j] = row[j];
}
}
// process columns
ComplexF[] col = new ComplexF[k];
for (int j = 0; j < n; j++)
{
// copy column
for (int i = 0; i < k; i++)
{
col[i] = data[i, j];
}
// transform it
FourierTransform.FFT(col, direction);
// copy back
for (int i = 0; i < k; i++)
{
data[i, j] = col[i];
}
}
}
/// <summary>
/// Two dimensional Fast Fourier Transform.
/// </summary>
/// <param name="width">Image width.</param>
/// <param name="height">Image height.</param>
/// <param name="stride">Image stride.</param>
/// <param name="data">Data to transform.</param>
/// <param name="direction">Transformation direction.</param>
///
/// <remarks><para><note>The method accepts <paramref name="data"/> array of 2<sup>n</sup> size
/// only in each dimension, where <b>n</b> may vary in the [1, 14] range. For example, 16x16 array
/// is valid, but 15x15 is not.</note></para></remarks>
///
/// <exception cref="ArgumentException">Incorrect data length.</exception>
///
public unsafe static void FFT2(ComplexF *data, int width, int height, int stride, Direction direction)
{
const int MIN_PATCH_SIZE = 32; //how much rows/columns should one thread process
int k = height;
int n = width;
// check data size
if (
(!AForge.Math.Tools.IsPowerOf2(k)) ||
(!AForge.Math.Tools.IsPowerOf2(n)) ||
(k < minLength) || (k > maxLength) ||
(n < minLength) || (n > maxLength)
)
{
throw new ArgumentException("Incorrect data length.");
}
// process rows
var procRow = new ParallelProcessor <bool, bool>(new Size(1 /*does not matter*/, height),
() => true,
(_, __, area) =>
{
ComplexF *dataPatchPtr = data + area.Y * stride / sizeof(ComplexF); //get row
for (int i = 0; i < area.Height; i++)
{
// transform it
FourierTransform.FFT(dataPatchPtr, n, direction);
dataPatchPtr += stride / sizeof(ComplexF);
}
},
new ParallelOptions2D {
ParallelTrigger = (size) => size.Height >= MIN_PATCH_SIZE
/*,ForceSequential = true*/ }
);
// process columns
//(y and x are swaped => proc thinks it is diving horizontal pacthes but instead we are using them as vertical ones)
var procCol = new ParallelProcessor <bool, bool>(new Size(1 /*does not matter*/, width),
() => true,
(_, __, area) =>
{
ComplexF *dataPatchPtr = &data[area.Y]; //get column
fixed(ComplexF * _col = new ComplexF[k])
{
ComplexF *col = _col;
for (int j = 0; j < area.Height; j++)
{
// copy column
ComplexF *dataColPtr = &dataPatchPtr[j];
for (int i = 0; i < k; i++)
{
col[i] = *dataColPtr;
dataColPtr += stride / sizeof(ComplexF);
}
// transform it
FourierTransform.FFT(col, k, direction);
// copy back
dataColPtr = &dataPatchPtr[j];
for (int i = 0; i < k; i++)
{
*dataColPtr = col[i];
dataColPtr += stride / sizeof(ComplexF);
}
}
}
},
new ParallelOptions2D {
ParallelTrigger = (size) => size.Height >= MIN_PATCH_SIZE
/*,ForceSequential = true */ }
);
procRow.Process(true);
procCol.Process(true);
}