The interpolation mode the effect uses to scale the image to the corresponding kernel unit length. There are six scale modes that range in quality and speed. If you don't select a mode, the effect uses the interpolation mode of the device context. See Scale modes for more info.

'Declaration
 
Public Property ScaleMode As DistantDiffuseScaleMode

public DistantDiffuseScaleMode ScaleMode {get; set;}