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How to declare OpenCV Mat object using Java?
In OpenCV Mat class represents a matrix object which is used to store images. You can also declare a Mat object manually −
Load the OpenCV native library − While writing Java code using OpenCV library, the first step you need to do is to load the native library of OpenCV using the loadLibrary().
Instantiate the Mat class − Instantiate the Mat class using any of the functions mentioned in this chapter earlier.
Fill the matrix using the methods − You can retrieve particular rows/columns of a matrix by passing index values to the methods row()/col().
you can set values to these using any of the variants of the setTo() methods.
Example
import org.opencv.core.Core;
import org.opencv.core.Mat;
import org.opencv.core.CvType;
import org.opencv.core.Scalar;
public class CreatingMat {
public static void main(String[] args) {
//Loading the core library
System.loadLibrary(Core.NATIVE_LIBRARY_NAME);
//Creating a matrix
Mat matrix = new Mat(5, 5, CvType.CV_8UC1, new Scalar(0));
//Adding values
Mat row0 = matrix.row(0);
row0.setTo(new Scalar(1));
Mat col3 = matrix.col(3);
col3.setTo(new Scalar(3));
//Printing the matrix
System.out.println("Matrix data:\n" + matrix.dump());
}
}Output
Matrix data: [ 1, 1, 1, 3, 1; 0, 0, 0, 3, 0; 0, 0, 0, 3, 0; 0, 0, 0, 3, 0; 0, 0, 0, 3, 0 ]
Updated on: 09-Apr-2020
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