imopen

Morphologically open image

Syntax

J = imopen(I,SE)

J = imopen(I,nhood)

gpuarrayJ = imopen(gpuarrayI,___)

Description

J = imopen(I,SE) performs morphological opening on the grayscale or binary image I, returning the opened image, J. SE is a single structuring element object returned by the strel or offsetstrel functions. The morphological open operation is an erosion followed by a dilation, using the same structuring element for both operations.

J = imopen(I,nhood) opens the image I, where nhood is a matrix of 0s and 1s that specifies the structuring element neighborhood. This is equivalent to the syntax imopen(I,strel(nhood)). The imopen function determines the center element of the neighborhood by floor((size(nhood)+1)/2).

gpuarrayJ = imopen(gpuarrayI,___) opens an image, using a GPU. This syntax requires Parallel Computing Toolbox™.

Examples

Morphologically Open Image with a Disk-Shaped Structuring Element

Read the image into the workspace and display it.

original = imread('snowflakes.png');
imshow(original);

Create a disk-shaped structuring element with a radius of 5 pixels.

se = strel('disk',5);

Remove snowflakes having a radius less than 5 pixels by opening it with the disk-shaped structuring element.

afterOpening = imopen(original,se);
figure
imshow(afterOpening,[]);

Morphologically Open Image with Disk-Shaped Structuring Element on a GPU

Read an image.

 original = imread('snowflakes.png');

Create a disk-shaped structuring element.

se = strel('disk',5);

Morphologically open the image on a GPU, using a gpuArray object, and display the images.

afterOpening = imopen(gpuArray(original),se);
figure, imshow(original), figure, imshow(afterOpening,[])

Input Arguments

I — Input image

grayscale image | binary image

Input image, specified as a grayscale image or binary image. I can have any dimension, and must be real and nonsparse.

Data Types: single | double | int8 | int16 | int32 | uint8 | uint16 | uint32 | logical

SE — Structuring element

strel object | offsetstrel object

Structuring element, specified as a single strel object or offsetstrel object. If the image I is data type logical, the structuring element must be flat.

nhood — Structuring element neighborhood

matrix of 0s and 1s

Structuring element neighborhood, specified as a matrix of 0s and 1s.

Example: [0 1 0; 1 1 1; 0 1 0]

gpuarrayI — Image to be opened on a GPU

gpuArray

Image to be opened on a GPU, specified as a gpuArray containing an image of type uint8 or logical. The structuring element SE must be flat and two-dimensional.

Output Arguments

J — Opened image

grayscale image | binary image

Opened image, returned as a grayscale image or binary image. J has the same class as input image I.

gpuarrayJ — Opened image when run on a GPU

gpuArray

Opened image when run on a GPU, returned as a gpuArray. The output gpuarrayJ has the same class as the input gpuarrayI.

Extended Capabilities

C/C++ Code Generation

Generate C and C++ code using MATLAB® Coder™.

Usage notes and limitations:

• This function supports the generation of C code using MATLAB^® Coder™. Note that if you choose the generic MATLAB Host Computer target platform, the function 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 Understand Code Generation with Image Processing Toolbox.

• When generating code, the image input argument, IM, must be 2-D or 3-D and the structuring element input argument, SE, must be a compile-time constant.