BW = imregionalmax(I) returns
the binary image BW that identifies the regional maxima in
grayscale image I. Regional maxima are connected components of
pixels with a constant intensity value, surrounded by pixels with a lower
value.
BW = imregionalmax(I,conn)
specifies the pixel connectivity, conn.
Pixel connectivity, specified as one of the values in this table. The
default connectivity is 8 for 2-D images, and
26 for 3-D images.
Value
Meaning
Two-Dimensional Connectivities
4-connected
Pixels are connected if their edges touch. The neighborhood of a pixel
are the adjacent pixels in the horizontal or vertical
direction.
8-connected
Pixels are connected if their edges or corners touch. The neighborhood
of a pixel are the adjacent pixels in the horizontal, vertical, or diagonal
direction.
Three-Dimensional Connectivities
6-connected
Pixels are connected if their faces touch. The neighborhood of a pixel
are the adjacent pixels in:
One of these directions: in, out, left, right, up, and
down
18-connected
Pixels are connected if their faces or edges touch. The neighborhood of
a pixel are the adjacent pixels in:
One of these directions: in, out, left, right, up, and
down
A combination of two directions, such as right-down or
in-up
26-connected
Pixels are connected if their faces, edges, or corners touch. The
neighborhood of a pixel are the adjacent pixels in:
One of these directions: in, out, left, right, up, and
down
A combination of two directions, such as right-down or
in-up
A combination of three directions, such as in-right-up or
in-left-down
For higher dimensions, imregionalmax uses the default
value conndef(ndims(I),'maximal').
Connectivity can also be
defined in a more general way for any dimension by specifying a 3-by-3-by- ... -by-3 matrix of
0s and 1s. The 1-valued elements
define neighborhood locations relative to the center element of conn. Note
that conn must be symmetric about its center element. See Specifying Custom Connectivities for more information.
Locations of regional maxima, returned as a logical array of the same size
as I. Pixels with the value 1
indicate regional maxima; all other pixels are set to
0.
Data Types: logical
Extended Capabilities
C/C++ Code Generation Generate C and C++ code using MATLAB® Coder™.
Usage notes and limitations:
imregionalmax supports the generation of C
code (requires MATLAB®
Coder™). Note that if you choose the generic MATLAB Host Computer
target platform, imregionalmax generates code that uses a precompiled,
platform-specific shared library. Use of a shared library preserves performance optimizations
but limits the target platforms for which code can be generated. For more information, see Code Generation Using a Shared Library.
When generating code, the optional second input argument,
conn, must be a compile-time constant.
GPU Arrays Accelerate code by running on a graphics processing unit (GPU) using Parallel Computing Toolbox™.
Usage notes and limitations:
Inputs must be 2-D, supporting only the 2-D connectivities (4 and
8).
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