public static Vector <int>[,] ApplyDct(BitmapSource bitmap, DctParameters dctParameters)
{
var map = bitmap.GetMap();
var mapInYCbCr = ToYCbCr(map);
var decimatedMap = Decimate(mapInYCbCr, dctParameters.DecimationType);
var blocks = SplitToBlocks(decimatedMap, 8);
var dct = GetDctMatrix();
var transposedDct = dct.Transpose();
var appliedDct = ApplyDct(blocks, dct, transposedDct);
var quantizedDct = QuantizeMatrices(appliedDct, dctParameters);
return(Flatten(quantizedDct));
}
public static BitmapSource DecodeDct(DctParameters dctParameters)
{
var encoded = Jpeg.Load(dctParameters);
var encodedMatrices = SplitToBlocksInt(encoded, 8);
var dequantizedMatrices = DequantizeMatrices(encodedMatrices, dctParameters);
var dct = GetDctMatrix();
var transposedDct = dct.Transpose();
var inversedDct = ApplyDct(dequantizedMatrices, transposedDct, dct);
var flattened = FlattenByte(inversedDct);
var undecimated = Undecimate(flattened, dctParameters.DecimationType);
var inRgb = ToRgbBytes(undecimated);
return(BitmapSource.Create(undecimated.GetLength(0), undecimated.GetLength(1), 96.0, 96.0, PixelFormats.Bgr32,
null, inRgb, inRgb.Length / undecimated.GetLength(0)));
}
private static Vector <Matrix>[,] DequantizeMatrices(Vector <Matrix>[,] encodedMatrices, DctParameters dctParameters)
{
switch (dctParameters.QuantizationType)
{
case QuantizationType.LargestN:
return(encodedMatrices);
case QuantizationType.DefaultJpegMatrix:
return(DequantizeByMatrices(encodedMatrices, DefaultMatrixY, DefaultMatrixC));
case QuantizationType.QuantizationMatrix:
var matrixY = GetQuantizationMatrix(dctParameters.GeneratorsY);
var matrixC = GetQuantizationMatrix(dctParameters.GeneratorsC);
return(DequantizeByMatrices(encodedMatrices, matrixY, matrixC));
default:
throw new ArgumentOutOfRangeException();
}
}
private static Vector <Matrix>[,] QuantizeMatrices(Vector <Matrix>[,] appliedDct, DctParameters dctParameters)
{
switch (dctParameters.QuantizationType)
{
case QuantizationType.LargestN:
if (!dctParameters.Ny.HasValue || !dctParameters.Nc.HasValue)
{
throw new Exception("Invalid program state");
}
return(QuantizeLargest(appliedDct, dctParameters.Ny.Value, dctParameters.Nc.Value));
case QuantizationType.QuantizationMatrix:
var matrixY = GetQuantizationMatrix(dctParameters.GeneratorsY);
var matrixC = GetQuantizationMatrix(dctParameters.GeneratorsC);
return(QuantizeByMatrices(appliedDct, matrixY, matrixC));
case QuantizationType.DefaultJpegMatrix:
return(QuantizeByMatrices(appliedDct, DefaultMatrixY, DefaultMatrixC));
default:
throw new ArgumentOutOfRangeException();
}
}
