public override async IAsyncEnumerable <AlgorithmResultElement> AddWatermark([EnumeratorCancellation] CancellationToken ct)
{
complexImage = ComplexImage.FromBitmap(parameters.Original);
complexWatermark = ComplexImage.FromBitmap(parameters.Watermark, complexImage.Width);
ct.ThrowIfCancellationRequested();
complexImage.ForwardFourierTransform();
var fourierDomain = complexImage.ToEffectiveBitmapFourier();
yield return(new AlgorithmResultElement("Fourier domain (DFT)", fourierDomain.ToBitmap(parameters.Original.Size), new ResultDescription(ToString())));
ct.ThrowIfCancellationRequested();
complexWatermark.ForwardFourierTransform();
complexImage.EmbedImageFourier(complexWatermark, parameters.Key, parameters.Alpha);
var fourierDomainWatermarked = complexImage.ToEffectiveBitmapFourier();
yield return(new AlgorithmResultElement("DFT + watermark", fourierDomainWatermarked.ToBitmap(parameters.Original.Size), new ResultDescription(ToString())));
ct.ThrowIfCancellationRequested();
complexImage.BackwardFourierTransform();
var watermarked = complexImage.ToEffectiveBitmapFourier();
yield return(new AlgorithmResultElement("Watermarked", watermarked.ToBitmap(parameters.Original.Size), new ResultDescription(ToString())));
}
public override async IAsyncEnumerable <AlgorithmResultElement> RemoveWatermark([EnumeratorCancellation] CancellationToken ct)
{
ct.ThrowIfCancellationRequested();
ComplexImage complexWatermarked = ComplexImage.FromBitmap(parameters.Watermarked);
complexWatermarked.ForwardFourierTransform();
ct.ThrowIfCancellationRequested();
ComplexImage complexOriginal = ComplexImage.FromBitmap(parameters.Original);
complexOriginal.ForwardFourierTransform();
ct.ThrowIfCancellationRequested();
int[] v = new int[complexWatermarked.Width];
double[] vAlpha = new double[complexWatermarked.Width];
Random random = new Random(parameters.Key);
ct.ThrowIfCancellationRequested();
for (int i = 0; i < complexWatermarked.Width; i++)
{
v[i] = random.Next(0, 2);
vAlpha[i] = v[i] * parameters.Alpha;
}
ct.ThrowIfCancellationRequested();
for (int y = 0; y < complexWatermarked.Height; y++)
{
for (int x = 0; x < complexWatermarked.Width; x++)
{
double watermarkedReal = complexWatermarked.Data[y, x].Real;
double watermarkedImaginary = complexWatermarked.Data[y, x].Imaginary;
double originalReal = complexOriginal.Data[y, x].Real;
double originalImaginary = complexOriginal.Data[y, x].Imaginary;
if (vAlpha[x] == 0)
{
complexWatermarked.Data[y, x] = new System.Numerics.Complex(0, 0);
}
else
{
complexWatermarked.Data[y, x] = new System.Numerics.Complex((watermarkedReal - originalReal) / vAlpha[x], (watermarkedImaginary - originalImaginary) / vAlpha[x]);
}
}
}
ct.ThrowIfCancellationRequested();
yield return(new AlgorithmResultElement("Extracted watermark DFT", complexWatermarked.ToEffectiveBitmapFourier(true).ToBitmap(parameters.Original.Size), new ResultDescription(ToString())));
complexWatermarked.BackwardFourierTransform();
ct.ThrowIfCancellationRequested();
yield return(new AlgorithmResultElement("Extracted watermark", complexWatermarked.ToEffectiveBitmapFourier(true).ToBitmap(parameters.Original.Size), new ResultDescription(ToString())));
}