createMat

Create MATLAB interface object for OpenCV Mat class

Since R2021b

Syntax

[ocvMat,ocvInputArray] = createMat(img)

[ocvMat,ocvArray] = createMat(img,arrayType)

[ocvMat,ocvOutputArray] = createMat

[ocvMat,ocvArray] = createMat(arrayType)

Description

[ocvMat,ocvInputArray] = createMat(img) creates the MATLAB^® interface objects for the OpenCV Mat class and the associated InputArray class. Use these interface objects to pass an image as input to the OpenCV functions.

[ocvMat,ocvArray] = createMat(img,arrayType) creates the MATLAB interface objects for the OpenCV Mat class and the associated InputArray, OutputArray, or InputOutputArray class specified by arrayType.

[ocvMat,ocvOutputArray] = createMat creates an empty interface object for the OpenCV Mat class and the associated OutputArray class. Use this interface to write the output returned by an OpenCV function.

[ocvMat,ocvArray] = createMat(arrayType) creates an empty interface object for the OpenCV Mat class and the associated InputArray, OutputArray, or InputOutputArray class specified by arrayType.

Examples

Create MATLAB Interface Object for OpenCV Mat and Associated Array Classes

Add the prebuilt MATLAB interface to OpenCV package name to the import list.

import vision.opencv.util.*

Create MATLAB Interface Object for OpenCV Mat and InputArray Class

Read an image into the MATLAB workspace.

img = imread("cameraman.tif");

Create a MATLAB interface object for the OpenCV Mat class and store the image data. The function also creates an interface object for the OpenCV InputArray class that is constructed from the Mat class.

[ocvMat,ocvArray] = createMat(img);

Display and inspect the properties of the MATLAB interface object for the OpenCV Mat class.

ocvMat

ocvMat = 
  MatND with properties:

        flags: 1124024320
         dims: 2
         rows: 256
         cols: 256
    allocator: [1x1 clib.opencv.cv.MatAllocator]
            u: [1x1 clib.opencv.cv.UMatData]
         size: [1x1 clib.opencv.cv.MatSize]
         step: [1x1 clib.opencv.cv.MatStep]

Inspect the type of array class returned by the function.

ocvArray

ocvArray = 
  x_InputArray with no properties.

Use the getImage utility function to read the image stored in the InputArray class. Display the image.

outImg = getImage(ocvArray);
figure
imshow(outImg)

Create MATLAB Interface Object for OpenCV Mat and OutputArray Classes

Add the prebuilt MATLAB interface to OpenCV package name to the import list.

import vision.opencv.util.*

Create a MATLAB interface object for the OpenCV Mat class. The function also creates an interface object for the OpenCV OutputArray class that is constructed from the Mat class.

[ocvMat,ocvArray] = createMat;

Display and inspect the properties of the MATLAB interface object for the OpenCV Mat class.

ocvMat

ocvMat = 
  MatND with properties:

        flags: 1124007936
         dims: 0
         rows: 0
         cols: 0
    allocator: [1x1 clib.opencv.cv.MatAllocator]
            u: [1x1 clib.opencv.cv.UMatData]
         size: [1x1 clib.opencv.cv.MatSize]
         step: [1x1 clib.opencv.cv.MatStep]

Inspect the type of array class returned by the function.

ocvArray

ocvArray = 
  x_OutputArray with no properties.

Specify Array Class to Construct from OpenCV Mat Class

Add the prebuilt MATLAB interface to OpenCV package name to the import list.

import vision.opencv.util.*

Read an image into the MATLAB workspace.

img = imread("cameraman.tif");

Create a MATLAB interface object for the OpenCV Mat class. Specify the array type as "InputOutput" for the function to construct the OpenCV InputOutputArray class from the Mat class.

arrayType = "InputOutput";
[ocvMat,ocvArray] = createMat(img,arrayType);

Display and inspect the properties of the MATLAB interface object for the OpenCV Mat class.

ocvMat

ocvMat = 
  MatND with properties:

        flags: 1124024320
         dims: 2
         rows: 256
         cols: 256
    allocator: [1x1 clib.opencv.cv.MatAllocator]
            u: [1x1 clib.opencv.cv.UMatData]
         size: [1x1 clib.opencv.cv.MatSize]
         step: [1x1 clib.opencv.cv.MatStep]

Inspect the type of array class returned by the function.

ocvArray

ocvArray = 
  x_InputOutputArray with no properties.

Input Arguments

img — Input image

M-by-N matrix | M-by-N-by-3 array

Input image, specified as an M-by-N matrix representing an intensity image or M-by-N-by-3 array representing a color image.

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

arrayType — Type of array

"Input" | "Output" | "InputOutput"

Type of array to associate with the MATLAB interface object for the OpenCV Mat class, specified as: "Input", "Output", or "InputOutput".

Data Types: char | string

Output Arguments

ocvMat — n-dimensional dense array class

MatND interface object

n-dimensional dense array class, returned as a MatND interface object. This interface object is a representation of the OpenCV class cv::Mat.

ocvInputArray — Proxy class for passing inputs

InputArray interface object

Proxy class for passing inputs to OpenCV functions, returned as an InputArray interface object. This interface object is a representation of the OpenCV class cv::_InputArray.

ocvArray — Proxy class for inputs or outputs

InputArray interface object | InputOutputArray interface object | OutputArray interface object

Proxy class for inputs or outputs, returned as one of these values:

• InputArray interface object — This MATLAB interface object is a representation of the OpenCV class cv::_InputArray. This value is returned if arrayType is specified as "Input".

• InputOutputArray interface object — This MATLAB interface object is a representation of the OpenCV class cv::_InputOutputArray. This value is returned if arrayType is specified as "InputOutput".

• OutputArray interface object — This MATLAB interface object is a representation of the OpenCV class cv::_OutputArray. This value is returned if arrayType is specified as "Output".

ocvOutputArray — Proxy class for writing output

OutputArray interface object

Proxy class for writing outputs from OpenCV functions, returned as an OutputArray interface object. This MATLAB interface object is a representation of the OpenCV class cv::_OutputArray.

Version History

Introduced in R2021b