Description

The Label block labels the objects in a binary image, BW. The background is represented by pixels equal to 0 (black) and objects are represented by pixels equal to 1 (white). At the Label port, the block outputs a label matrix that is the same size as the input matrix. In the label matrix, pixels equal to 0 represent the background, pixels equal to 1 represent the first object, pixels equal to 2 represent the second object, and so on. At the Count port, the block outputs a scalar value that represents the number of labeled objects.

Use the Connectivity parameter to define which pixels are connected to each other. If you want a pixel to be connected to the other pixels located on the top, bottom, left, and right, select 4. If you want a pixel to be connected to the other pixels on the top, bottom, left, right, and diagonally, select 8.

Consider the following 3-by-3 image. If, for the Connectivity parameter, you select 4, the block considers the white pixels marked by black circles to be connected.

If, for the Connectivity parameter, you select 8, the block considers the white pixels marked by black circles to be connected.

Use the Output parameter to determine the block's output. If you select Label matrix and number of labels, ports Label and Count appear on the block. The block outputs the label matrix at the Label port and the number of labeled objects at the Count port. If you select Label matrix, the Label port appears on the block. If you select Number of labels, the Count port appears on the block.

Use the Output data type parameter to set the data type of the outputs at the Label and Count ports. If you select Automatic, the block calculates the maximum number of objects that can fit inside the image based on the image size and the connectivity you specified. Based on this calculation, it determines the minimum output data type size that guarantees unique region labels and sets the output data type appropriately. If you select uint32, uint16, or uint8, the data type of the output is 32-, 16-, or 8-bit unsigned integers, respectively. If you select uint16, or uint8, the If label exceeds data type size, mark remaining regions using parameter appears in the dialog box. If the number of found objects exceeds the maximum number that can be represented by the output data type, use this parameter to specify the block's behavior. If you select maximum value of the output data type, the remaining regions are labeled with the maximum value of the output data type. If you select zero, the remaining regions are labeled with zeroes.

Parameters

See Also