/// <summary>
/// Process the filter on the specified image.
/// </summary>
///
/// <param name="image">Source image data.</param>
/// <param name="rect">Image rectangle for processing by the filter.</param>
///
protected override unsafe void ProcessFilter(UnmanagedImage image, Rectangle rect)
{
// calculate threshold
thresholdFilter.ThresholdValue = CalculateThreshold(image, rect);
// thresholding
thresholdFilter.ApplyInPlace(image, rect);
}
