private void CalculateSection(int startIndex, int endIndex)
{
for (int i = startIndex; i < endIndex; i++)
{
for (int j = 0; j < _width; j++)
{
var value = Math.Max(0.0f, Math.Min(1.0, (double)Perlin.Function2D((double)i, (double)j) * 0.5 + 0.5));
// from 0.0 - 1.0 to 0 - 255 byte data
value = value * 255;
// assign values at rgb positions
this[i, j] = (byte)value;
}
}
}