public void Extract_message_from_stego_image()
{
string path = Path.Combine(basePath, "hided.jpg");
using (var stream = new StreamReader(path))
{
var reader = new JpegImageIO();
var bytes = reader.ReadRGBFromImage(stream.BaseStream);
//TestHelper.PrintMatrix("Stego img", bytes);
var matrix = YCrCb.Parse(bytes);
//TestHelper.PrintMatrix("Luminance Coeff", matrix);
var dct = new DCT();
//dct.Subsample(matrix);
dct.CalculateDCT(matrix);
//TestHelper.PrintMatrix("DCT", matrix);
new Quantizer().ApplyQuantization(matrix, qf);
// TestHelper.PrintMatrix("QDCT", matrix);
var stego = new Steganography();
var message = stego.ExtractMessage(matrix);
Console.WriteLine(message);
}
}
public void Matrix_is_the_same_when_DCT_and_IDCT_are_aplied()
{
var matrix = convertToYCrCb(new double[,]
{
{26, 26, 26, 25, 25, 25, 26, 26},
{26, 26, 26, 25, 25, 25, 26, 26},
{26, 26, 26, 25, 25, 25, 26, 26},
{26, 26, 26, 25, 25, 25, 26, 26},
{26, 26, 26, 25, 25, 25, 26, 26},
{26, 26, 26, 25, 25, 25, 26, 26},
{26, 26, 26, 25, 25, 25, 26, 26},
{26, 26, 26, 25, 25, 25, 26, 26},
});
var expectedMatrix = MatrixUtil.Copy(matrix);
DCT dct = new DCT();
TestHelper.PrintMatrix("DCT", matrix);
dct.CalculateDCT(matrix);
TestHelper.PrintMatrix("DCT", matrix);
dct.CalculateIDCT(matrix);
var doubleExpectedMatrix = convertToDouble(expectedMatrix);
var doubleMatrix = convertToDouble(matrix);
CollectionAssert.AreEquivalent(doubleExpectedMatrix, doubleMatrix);
}
public void EmbedData(string path, byte[] message)
{
using (var stream = new StreamReader(path))
{
var imageIo = new JpegImageIO();
var bytesRGB = imageIo.ReadRGBFromImage(stream.BaseStream);
var matrix = YCrCb.Parse(bytesRGB);
var dct = new DCT();
dct.CalculateDCT(matrix);
Quantizer q = new Quantizer();
q.ApplyQuantization(matrix, Qf);
var stego = new Steganography();
stego.HideMessage(matrix, message);
q.ApplyInverseQuantization(matrix, Qf);
dct.CalculateIDCT(matrix);
string pathToSave = Path.Combine(Path.GetDirectoryName(path), Path.GetFileNameWithoutExtension(path) + "_stego.jpg");
imageIo.WriteRGBToImage(pathToSave, RGB.Parse(matrix));
}
}
public byte[] ExtractData(string path)
{
using (var stream = new StreamReader(path))
{
var reader = new JpegImageIO();
var bytes = reader.ReadRGBFromImage(stream.BaseStream);
var matrix = YCrCb.Parse(bytes);
var dct = new DCT();
dct.CalculateDCT(matrix);
new Quantizer().ApplyQuantization(matrix, Qf);
var stego = new Steganography();
return stego.ExtractMessage(matrix);
}
}
