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labelmatrix - Create label matrix from `bwconncomp` structure

Syntax

L = labelmatrix(CC)

Description

L = labelmatrix(CC) creates a label matrix from the connected components structure CC returned by bwconncomp. The size of L is CC.ImageSize. The elements of L are integer values greater than or equal to 0. The pixels labeled 0 are the background. The pixels labeled 1 make up one object; the pixels labeled 2 make up a second object; and so on. The class of L depends on CC.NumObjects, as shown in the following table.

Class	Range
`'uint8'`	`CC.NumObjects` 255
`'uint16'`	256 `CC.NumObjects` 65535
`'uint32'`	65536 `CC.NumObjects`
`'double'`	`CC.NumObjects`

labelmatrix is more memory efficient than bwlabel and bwlabeln because it returns its label matrix in the smallest numeric class necessary for the number of objects.

Class Support

CC is a structure returned by bwconncomp. The label matrix L is uint8, uint16, uint32, or double.

Example

Calculate the connected components and display results:

BW = imread('text.png');
CC = bwconncomp(BW);
L = labelmatrix(CC);
L2 = bwlabel(BW);

whos L L2

The output for whos appears as follows:

Name        Size              Bytes  Class     Attributes

  L         256x256             65536  uint8               
  L2        256x256            524288  double