/// <summary>
/// Main Jpeg decode
/// </summary>
/// <param name="source">source bits</param>
/// <param name="qf">Quality factor</param>
/// <returns>decoded bytes</returns>
public byte[] Decode(string source, int qf)
{
_blocks.Clear();
_dctedBlocks.Clear();
_quantizedBlocks.Clear();
// construct RLE blocks
List <RLEBlock> rleblocks = CodeWordEncoder.ReconstructRleBlocks(source);
// inverse RLE
_quantizedBlocks = _rlEncoder.Decode(rleblocks);
//inverse quantization
_quantizedBlocks.ForEach(quatizedBlock =>
{
IQuantize(quatizedBlock, qf);
_dctedBlocks.Add(quatizedBlock);
});
// inverse dct
_dctedBlocks.ForEach(dctedBlocks =>
{
var array = dctedBlocks.ToArray();
CosineTransform.IDCT(array);
var matrix = Matrix <double> .Build.DenseOfArray(array);
matrix = matrix.Add(128);
_blocks.Add(matrix);
});
// reconstruct image from blocks
return(Construct8x8Block(_blocks));
}
/// <summary>
/// Main Jpeg encode
/// </summary>
/// <param name="source">source data</param>
/// <param name="qf">quality factor</param>
/// <returns>encoded bytes</returns>
public byte[] Encode(byte[] source, int qf)
{
// divide into 8x8
Divide8x8Block(source);
// do dct for every 8x8 block
_blocks.ForEach(block =>
{
block = block.Subtract(128);
var array = block.ToArray();
CosineTransform.DCT(array);
var matrix = Matrix <double> .Build.DenseOfArray(array);
_dctedBlocks.Add(matrix);
});
// do quantization
_dctedBlocks.ForEach(dctedBlocks =>
{
Quantize(dctedBlocks, qf);
_quantizedBlocks.Add(dctedBlocks);
});
// do RLE
List <RLEBlock> rleBlocks = _rlEncoder.Encode(_quantizedBlocks);
// construct code word by RLE
return(Utility.BoolArrayToByteArray(CodeWordEncoder.ConstructCodeWord(rleBlocks)));
}
