/// <summary>
/// Run-length decode ( RLE blocks -> zigzaged image blocks -> inverse zigzag -> origin image block )
/// </summary>
/// <param name="source">source data bits</param>
/// <returns></returns>
public List <Matrix <double> > Decode(IEnumerable <RLEBlock> source)
{
List <Matrix <double> > result = new List <Matrix <double> >();
int latestDc = 0;
foreach (RLEBlock rleBlock in source)
{
List <double> array = new List <double>();
DCElement dc = rleBlock.DC;
array.Add(dc.Diff + latestDc);
latestDc = dc.Diff + latestDc;
foreach (ACElement ac in rleBlock.ACs)
{
for (int i = 0; i < ac.Length; i++)
{
array.Add(0);
}
array.Add(ac.Value);
}
if (array.Count < 64)
{
int numOfZero = 64 - array.Count;
for (int i = 0; i < numOfZero; i++)
{
array.Add(0);
}
}
result.Add(ZigZagEncoder.IZigZag(array));
}
return(result);
}
/// <summary>
/// Run-length encode , ( origin image blocks -> zigzaged image blocks -> RLE blocks )
/// </summary>
/// <param name="source">image blocks</param>
/// <returns></returns>
public List <RLEBlock> Encode(List <Matrix <double> > source)
{
List <RLEBlock> blocks = new List <RLEBlock>();
int lastesrDC = 0;
int run = 0;
foreach (Matrix <double> matrix in source)
{
run = 0;
List <double> list = ZigZagEncoder.ZigZag(matrix);
List <ACElement> acs = new List <ACElement>();
int diff = (int)list[0] - lastesrDC;
lastesrDC = (int)list[0];
DCElement dc = new DCElement(diff);
List <double> listac = list.Skip(1).ToList();
foreach (double data in listac)
{
if (data == 0)
{
run++;
}
else
{
if (run >= 16)
{
int times = run / 16;
run %= 16;
for (int i = 0; i < times; i++)
{
acs.Add(new ACElement(15, 0));
}
}
acs.Add(new ACElement(run, (int)data));
run = 0;
}
}
blocks.Add(new RLEBlock(dc, acs));
}
return(blocks);
}
