Image Processing Toolbox

conndef

Create connectivity array

Syntax

• CONN = conndef(NUM_DIMS,TYPE)
  

Description

CONN = conndef(NUM_DIMS,TYPE) returns the connectivity array defined by TYPE for NUM_DIMS dimensions. TYPE can have either of the values listed in this table.

'minimal'	Defines a neighborhood whose neighbors are touching the central element on an (N-1)-dimensional surface, for the N-dimensional case. See Examples for an illustration.
'maximal'	Defines a neighborhood including neighbors that touch the central element in any way; it is ones(repmat(3,1,NUM_DIMS)). See Examples for an illustration.

Several Image Processing Toolbox functions use conndef to create the default connectivity input argument.

Examples

The minimal connectivity array for two dimensions includes the neighbors touching the central element along a line.

• conn1 = conndef(2,'minimal')
  
  conn1 =
       0     1     0
       1     1     1
       0     1     0
  

The minimal connectivity array for three dimensions includes all the neighbors touching the central element along a face.

• conndef(3,'minimal')
  
  ans(:,:,1) =
       0     0     0
       0     1     0
       0     0     0
  
  ans(:,:,2) =
       0     1     0
       1     1     1
       0     1     0
  
  ans(:,:,3) =
       0     0     0
       0     1     0
       0     0     0
  

The maximal connectivity array for two dimensions includes all the neighbors touching the central element in any way.

• conn2 = conndef(2,'maximal')
  
  conn2 =
       1     1     1
       1     1     1
       1     1     1
  

colorbar

conv2