public string ExtractArea(IntField image, int x, int y, out int mostFreqSymbol, out int secondFreqSymbol)
{
mostFreqSymbol = secondFreqSymbol = int.MinValue;
if (x < _width - 1 - _xpos || x >= image.Width - _xpos || y < _height - 1)
{
return(null);
}
IntField area = image.Extract(x - _width + 1 + _xpos, y - _height + 1, _width, _height);
int[] data = new int[area.Data.Length - 1 - _xpos];
Array.Copy(area.Data, data, data.Length);
// Find the smallest most frequent and second most frequent symbols
var counts = CodecUtil.CountValues(data);
ulong mostFreq = ulong.MinValue;
ulong secondFreq = ulong.MinValue;
for (int i = 0; i < counts.Length; i++)
{
if (counts[i] > mostFreq)
{
secondFreq = mostFreq;
secondFreqSymbol = mostFreqSymbol;
mostFreq = counts[i];
mostFreqSymbol = i;
}
else if (counts[i] > secondFreq)
{
secondFreq = counts[i];
secondFreqSymbol = i;
}
}
// Convert to string
StringBuilder SB = new StringBuilder(data.Length);
foreach (var sym in data)
{
SB.Append(sym == mostFreqSymbol ? "1" : "0");
}
return(SB.ToString());
}