bwmorph - Morphological operations on binary images

'bothat'

Performs the morphological "bottom hat" operation, returning the image minus the morphological closing of the image (dilation followed by erosion).

'branchpoints'

Find branch points of skeleton. For example:

0  0  1  0  0           0  0  0  0  0
0  0  1  0  0  becomes  0  0  0  0  0
1  1  1  1  1           0  0  1  0  0
0  0  1  0  0           0  0  0  0  0
0  0  1  0  0           0  0  0  0  0

'bridge'

Bridges unconnected pixels, that is, sets 0-valued pixels to 1 if they have two nonzero neighbors that are not connected. For example:

1  0  0           1  1  0 
1  0  1  becomes  1  1  1 
0  0  1           0  1  1

'clean'

Removes isolated pixels (individual 1s that are surrounded by 0s), such as the center pixel in this pattern.

0  0  0 
0  1  0 
0  0  0

'close'

Performs morphological closing (dilation followed by erosion).

'diag'

Uses diagonal fill to eliminate 8-connectivity of the background. For example:

0  1  0           0  1  0 
1  0  0  becomes  1  1  0 
0  0  0           0  0  0

'dilate'

Performs dilation using the structuring element ones(3).

'endpoints'

Finds end points of skeleton. For example:

1  0  0  0           1  0  0  0
0  1  0  0  becomes  0  0  0  0
0  0  1  0           0  0  1  0
0  0  0  0           0  0  0  0

'erode'

Performs erosion using the structuring element ones(3).

'fill'

Fills isolated interior pixels (individual 0s that are surrounded by 1s), such as the center pixel in this pattern.

1  1  1 
1  0  1 
1  1  1

'hbreak'

Removes H-connected pixels. For example:

1  1  1           1  1  1 
0  1  0  becomes  0  0  0 
1  1  1           1  1  1

'majority'

Sets a pixel to 1 if five or more pixels in its 3-by-3 neighborhood are 1s; otherwise, it sets the pixel to 0.

'open'

Performs morphological opening (erosion followed by dilation).

'remove'

Removes interior pixels. This option sets a pixel to 0 if all its 4-connected neighbors are 1, thus leaving only the boundary pixels on.

'shrink'

With n = Inf, shrinks objects to points. It removes pixels so that objects without holes shrink to a point, and objects with holes shrink to a connected ring halfway between each hole and the outer boundary. This option preserves the Euler number.

'skel'

With n = Inf, removes pixels on the boundaries of objects but does not allow objects to break apart. The pixels remaining make up the image skeleton. This option preserves the Euler number.

'spur'

Removes spur pixels. For example:

0  0  0  0           0  0  0  0
0  0  0  0           0  0  0  0
0  0  1  0  becomes  0  0  0  0
0  1  0  0           0  1  0  0
1  1  0  0           1  1  0  0

'thicken'

With n = Inf, thickens objects by adding pixels to the exterior of objects until doing so would result in previously unconnected objects being 8-connected. This option preserves the Euler number.

'thin'

With n = Inf, thins objects to lines. It removes pixels so that an object without holes shrinks to a minimally connected stroke, and an object with holes shrinks to a connected ring halfway between each hole and the outer boundary. This option preserves the Euler number. See Algorithm for more detail.

'tophat'

Performs morphological "top hat" operation, returning the image minus the morphological opening of the image (erosion followed by dilation).