private static square[,] CalculateDiff(square[,] integralImage, int whalf)
{
var result = new square[integralImage.Height(), integralImage.Width()];
for (int i = 0; i < result.Height(); i++)
{
for (int j = 0; j < result.Width(); j++)
{
var xmin = Math.Max(0, i - whalf);
var ymin = Math.Max(0, j - whalf);
var xmax = Math.Min(result.Height() - 1, i + whalf);
var ymax = Math.Min(result.Width() - 1, j + whalf);
if (xmin == 0 && ymin == 0)
{
result[i, j] = integralImage[xmax, ymax];
}
else if (xmin == 0)
{
result[i, j] = integralImage[xmax, ymax] - integralImage[xmax, ymin - 1];
}
else if (ymin == 0)
{
result[i, j] = integralImage[xmax, ymax] - integralImage[xmin - 1, ymax];
}
else
{
result[i, j] = integralImage[xmax, ymax] - integralImage[xmin - 1, ymax] - integralImage[xmax, ymin - 1] + integralImage[xmin - 1, ymin - 1];
}
}
}
return(result);
}
