public static Bitmap ifft2d(Bitmap input)
{
int width = (int)Math.Pow(2, Math.Ceiling(Math.Log(input.Width, 2)));
int height = (int)Math.Pow(2, Math.Ceiling(Math.Log(input.Width, 2)));
byte[] data = ImageUtils.GreyScale(input);
if (width != input.Width || height != input.Height)
{
// Pad data
byte[] newdata = new byte[width * height];
int xoff = width - input.Width;
int yoff = height - input.Height;
for (int i = 0; i < input.Height; i++)
{
for (int k = 0; k < input.Width; k++)
{
newdata[(i + yoff) * width + k + xoff] = data[i * input.Width + k];
}
}
data = newdata;
}
Complex[,] cmplx = new Complex[height, width];
double scale = 1.0 / (double)Math.Sqrt(width * height);
scale = 1;
for (int i = 0; i < data.Length; i++)
{
cmplx[i / width, i % width] = new Complex(data[i] / 256.0);
}
cmplx = ifft2d(cmplx);
for (int i = 0; i < height; i++)
{
for (int k = 0; k < width; k++)
{
if (((k + i) & 0x1) != 0)
{
cmplx[i, k] *= -1;
}
}
}
for (int i = 0; i < data.Length; i++)
{
data[i] = (byte)Math.Min(255, (int)(cmplx[i / width, i % width].GetModulus() * 256.0 * scale));
}
Bitmap output = ImageUtils.GetBitmap(data, PixelFormat.Format8bppIndexed, width, height);
return(output);
}
public static Bitmap fft2dRGB(Bitmap input, bool reorder)
{
int width = input.Width;
int height = input.Height;
ImageUtils.RGB[] data = ImageUtils.SplitColorChannels(input);
Complex[,] cmplxR = new Complex[height, width];
Complex[,] cmplxG = new Complex[height, width];
Complex[,] cmplxB = new Complex[height, width];
double scale = 1.0 / (double)Math.Sqrt(width * height);
for (int i = 0; i < data.Length; i++)
{
cmplxR[i / width, i % width] = new Complex(data[i].r / 256.0);
cmplxG[i / width, i % width] = new Complex(data[i].g / 256.0);
cmplxB[i / width, i % width] = new Complex(data[i].b / 256.0);
}
cmplxR = fft2d(cmplxR);
cmplxG = fft2d(cmplxG);
cmplxB = fft2d(cmplxB);
for (int i = 0; i < data.Length; i++)
{
data[i].r = (byte)Math.Min(255, (int)(cmplxR[i / width, i % width].GetModulus() * 256.0) * scale);
data[i].g = (byte)Math.Min(255, (int)(cmplxG[i / width, i % width].GetModulus() * 256.0) * scale);
data[i].b = (byte)Math.Min(255, (int)(cmplxB[i / width, i % width].GetModulus() * 256.0) * scale);
}
// Swapping data -> lowest frequencies at center
if (reorder)
{
for (int i = 0; i < height / 2; i++)
{
for (int k = 0; k < width / 2; k++)
{
ImageUtils.RGB val1 = data[i * width + k];
ImageUtils.RGB val2 = data[i * width + k + width / 2];
data[i * width + k] = data[(i + width / 2) * width + k + width / 2];
data[(i + width / 2) * width + k + width / 2] = val1;
data[i * width + k + width / 2] = data[(i + width / 2) * width + k];
data[(i + width / 2) * width + k] = val2;
}
}
}
Bitmap output = ImageUtils.GetBitmap(ImageUtils.CombineColorChannels(data), input.PixelFormat, width, height);
return(output);
}
public static Bitmap fft2d(Bitmap input, bool reorder)
{
int width = input.Width;
int height = input.Height;
byte[] data = ImageUtils.GreyScale(input);
Complex[,] cmplx = new Complex[height, width];
double scale = 1.0 / (double)Math.Sqrt(width * height);
for (int i = 0; i < data.Length; i++)
{
cmplx[i / width, i % width] = new Complex(data[i] / 256.0);
}
cmplx = fft2d(cmplx);
for (int i = 0; i < data.Length; i++)
{
data[i] = (byte)Math.Min(255, (int)(cmplx[i / width, i % width].GetModulus() * 256.0) * scale);
}
// Swapping data -> lowest frequencies at center
if (reorder)
{
for (int i = 0; i < height / 2; i++)
{
for (int k = 0; k < width / 2; k++)
{
byte val1 = data[i * width + k];
byte val2 = data[i * width + k + width / 2];
data[i * width + k] = data[(i + width / 2) * width + k + width / 2];
data[(i + width / 2) * width + k + width / 2] = val1;
data[i * width + k + width / 2] = data[(i + width / 2) * width + k];
data[(i + width / 2) * width + k] = val2;
}
}
}
Bitmap output = ImageUtils.GetBitmap(data, PixelFormat.Format8bppIndexed, width, height);
return(output);
}
public static Bitmap ifft2dRGB(Bitmap input)
{
int width = (int)Math.Pow(2, Math.Ceiling(Math.Log(input.Width, 2)));
int height = (int)Math.Pow(2, Math.Ceiling(Math.Log(input.Width, 2)));
ImageUtils.RGB[] data = ImageUtils.SplitColorChannels(input);
if (width != input.Width || height != input.Height)
{
// Pad data
ImageUtils.RGB[] newdata = new ImageUtils.RGB[width * height];
int xoff = width - input.Width;
int yoff = height - input.Height;
for (int i = 0; i < input.Height; i++)
{
for (int k = 0; k < input.Width; k++)
{
newdata[(i + yoff) * width + k + xoff] = data[i * input.Width + k];
}
}
data = newdata;
}
Complex[,] cmplxR = new Complex[height, width];
Complex[,] cmplxG = new Complex[height, width];
Complex[,] cmplxB = new Complex[height, width];
double scale = 1.0 / (double)Math.Sqrt(width * height);
scale = 1;
for (int i = 0; i < data.Length; i++)
{
cmplxR[i / width, i % width] = new Complex(data[i].r / 256.0);
cmplxG[i / width, i % width] = new Complex(data[i].g / 256.0);
cmplxB[i / width, i % width] = new Complex(data[i].b / 256.0);
}
cmplxR = ifft2d(cmplxR);
cmplxG = ifft2d(cmplxG);
cmplxB = ifft2d(cmplxB);
for (int i = 0; i < height; i++)
{
for (int k = 0; k < width; k++)
{
if (((k + i) & 0x1) != 0)
{
cmplxR[i, k] *= -1;
cmplxG[i, k] *= -1;
cmplxB[i, k] *= -1;
}
}
}
for (int i = 0; i < data.Length; i++)
{
data[i].r = (byte)Math.Min(255, (int)(cmplxR[i / width, i % width].GetModulus() * 256.0 * scale));
data[i].g = (byte)Math.Min(255, (int)(cmplxG[i / width, i % width].GetModulus() * 256.0 * scale));
data[i].b = (byte)Math.Min(255, (int)(cmplxB[i / width, i % width].GetModulus() * 256.0 * scale));
}
Bitmap output = ImageUtils.GetBitmap(ImageUtils.CombineColorChannels(data), input.PixelFormat, width, height);
return(output);
}