Could be 5x5..21x21. Correspondence using Sum of Absolute Difference (SAD):

Namespace: Emgu.CV.Structure
Assembly: Emgu.CV (in Emgu.CV.dll) Version: 2.2.1.1150 (2.2.1.1150)

Syntax

         
 C#  Visual Basic  Visual C++ 
public int SADWindowSize
Public SADWindowSize As Integer
public:
int SADWindowSize

See Also