StructureElement = CreateStructureElement(Name, Parameter)
a string, can be 'circle', 'square', 'rectangle', 'vertical_line' , 'horizontal_line' or 'custom'. Name is not case sensitive.
specifies the size of the structuring element if Name is not 'custom'. If Name is 'rectangle', Dimensions must be a vector containing the width in the first and the height in the second component. For all other values of Name, Dimensions must be a scalar. If name is 'circle', Parameter is the radius of the circle.
If Name is 'custom', Parameter must be a boolean 2D matrix.
struct with the components
Width: number of columns of structuring element
Height: number of rows of structuring element
Data: boolean matrix