private static void applyDwtDctWatermarkOnColorSpace(double[,] colorSpaceTarget, double[,] greyScaleWatermark)
{
var a = colorSpaceTarget[0, 0];
var flattened = greyScaleWatermark.Cast <double>().ToArray();
DWTTransform.ForwardTransform(colorSpaceTarget, 2);
var subBandTarget = WatermarkUtils.Ll1(colorSpaceTarget);
var midband = GetMidBand(DCT_BLOCK_SIZE);
var embeddingBlockLength = subBandTarget.GetLength(0);
var midBandOneElementsCount = midband.Cast <double>().Count(el => (int)el == 1);
var(pnSequenceZero, pnSequenceOne) = GenerateUncorelatedPnSequences(midBandOneElementsCount);
var x = 0;
var y = 0;
for (int i = 0; i < flattened.Length; i++)
{
var block = subBandTarget.Submatrix(y, y + DCT_BLOCK_SIZE - 1,
x, x + DCT_BLOCK_SIZE - 1);
DCTTransform.DCT(block);
var ll = 0;
for (int j = 0; j < midband.GetLength(0); j++)
{
for (int k = 0; k < midband.GetLength(1); k++)
{
if (midband[j, k] == 1)
{
var elementToAdd = flattened[i] == 0 ? pnSequenceOne[ll] : pnSequenceZero[ll];
block[j, k] = block[j, k] + elementToAdd * WATERMARK_FACTOR;
ll++;
}
}
}
DCTTransform.IDCT(block);
subBandTarget.ApplyDataBlock(block, y, x);
x += DCT_BLOCK_SIZE;
if (x + DCT_BLOCK_SIZE >= embeddingBlockLength)
{
x = 1;
y += DCT_BLOCK_SIZE;
if (y >= embeddingBlockLength)
{
break;
}
}
}
;
WatermarkUtils.ApplyLl1SubBand(colorSpaceTarget, subBandTarget);
DWTTransform.InverseWaveletTransform(colorSpaceTarget, 2);
}
private static Bitmap ExtractDwtDctWatermark(double[,] iWatermarked, double[,] greyScaleWatermark)
{
var flattened = greyScaleWatermark.Cast <double>().ToArray();
DWTTransform.ForwardTransform(iWatermarked, 2);
var subBandTarget = WatermarkUtils.Ll1(iWatermarked);
var midband = GetMidBand(DCT_BLOCK_SIZE);
var embeddingBlockLength = subBandTarget.GetLength(0);
var midBandOneElementsCount = midband.Cast <double>().Count(el => (int)el == 1);
var(pnSequenceZero, pnSequenceOne) = GenerateUncorelatedPnSequences(midBandOneElementsCount);
var sequence = new double[pnSequenceOne.Count];
var correlationZero = new double[flattened.Length];
var correlationOne = new double[flattened.Length];
var x = 0;
var y = 0;
for (var i = 0; i < flattened.Length; i++)
{
var block = subBandTarget.Submatrix(y, y + DCT_BLOCK_SIZE - 1,
x, x + DCT_BLOCK_SIZE - 1);
DCTTransform.DCT(block);
var ll = 0;
for (var j = 0; j < midband.GetLength(0); j++)
{
for (var k = 0; k < midband.GetLength(1); k++)
{
if (midband[j, k] == 1)
{
sequence[ll] = block[j, k];
ll++;
}
}
}
correlationZero[i] = Correlation.Pearson(pnSequenceZero, sequence);
correlationOne[i] = Correlation.Pearson(pnSequenceOne, sequence);
x += DCT_BLOCK_SIZE;
if (x + DCT_BLOCK_SIZE >= embeddingBlockLength)
{
x = 1;
y += DCT_BLOCK_SIZE;
if (y >= embeddingBlockLength)
{
break;
}
}
}
var reconstructedImage = new int [flattened.Length];
for (var i = 0; i < flattened.Length; i++)
{
if (correlationZero[i] > correlationOne[i])
{
reconstructedImage[i] = 255;
}
else
{
reconstructedImage[i] = 0;
}
}
var imgLength = greyScaleWatermark.GetLength(0);
var img = new int[greyScaleWatermark.GetLength(0), greyScaleWatermark.GetLength(1)];
for (var i = 0; i < reconstructedImage.Length; i++)
{
img[i / imgLength, i % imgLength] = reconstructedImage[i];
}
return(BitmapUtils.CreateGeyscaleImage(img));
}