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Object Oriented Programming Articles
Page 470 of 589
How to perform Bitwise And operation on two images using Java OpenCV?
You can compute bitwise conjunction between two images using the bitwise_and() method of the org.opencv.core.Core class.This method accepts three Mat objects representing the source, destination and result matrices, calculates the bitwise conjunction of each every element in the source matrices and stores the result in the destination matrix.ExampleIn the following Java example we are converting an image into binary and gray scale and calculating the bitwise conjunction of the results.import org.opencv.core.Core; import org.opencv.core.Mat; import org.opencv.highgui.HighGui; import org.opencv.imgcodecs.Imgcodecs; import org.opencv.imgproc.Imgproc; public class BitwiseAndExample { public static void main(String args[]) throws Exception { //Loading the OpenCV core library ...
Read MoreHow to draw a polygon in OpenCV using Java?
A polygon with all the interior angles less than 180 is known as a convex polygon. The org.opencv.imgproc package of Java OpenCV library contains a class named Imgproc. To draw a polygon you need to invoke the fillConvexPoly() method of this class. This method accepts 3 parameters −A Mat object representing the image on which the polygon is to be drawn.A MatOfPoint object points between which the polygon is to be drawn.A Scalar object representing the color of the polygon.Exampleimport org.opencv.core.Core; import org.opencv.core.Mat; import org.opencv.core.MatOfPoint; import org.opencv.core.Point; import org.opencv.core.Scalar; import org.opencv.highgui.HighGui; import org.opencv.imgcodecs.Imgcodecs; import org.opencv.imgproc.Imgproc; public class DrawingConvexPolygon { public ...
Read MoreHow to draw a filled circle in OpenCV using Java?
The org.opencv.imgproc package of Java OpenCV library contains a class named Imgproc. This class provides a method named circle(), using this you can draw a circle on an image. This method provides the following parameters −A Mat object representing the image on which the circle is to be drawn.A Point object representing the center of the circle.An integer variable representing the radius of the circle.A Scalar object representing the color of the circle(BGR).An integer representing the thickness of the circle(default 1).If you pass Imgproc.FILLEDas line type, this method generates/draws a filled circle.Exampleimport org.opencv.core.Core; import org.opencv.core.Mat; import org.opencv.core.Point; import org.opencv.core.Scalar; import ...
Read MoreHow to convert OpenCV Mat object to JavaFX WritableImage?
If you try to read an image using the OpenCV imread() method it returns a Mat object. If you want to display the contents of the resultant Mat object using a JavaFX window You need to convert the Mat object to an object of the class javafx.scene.image.WritableImage. To do so, you need to follow the steps given below −Encode the Mat to MatOfByte − First of all, you need to convert the matrix to the matrix of a byte. You can do it using the method imencode() of the class Imgcodecs.This method accepts a String parameter(specifying the image format), a ...
Read MoreHow to create a database in MongoDB using Java?
There is no separate method to create a MongoDB database in Java, you can create a database by invoking the getDatabase() method of the com.mongodb.MongoClient class.Exampleimport com.mongodb.MongoClient; public class CreatingDatabase { public static void main( String args[] ) { //Creating a MongoDB client @SuppressWarnings("resource") MongoClient mongo = new MongoClient( "localhost" , 27017 ); //Accessing the database mongo.getDatabase("myDatabase1"); mongo.getDatabase("myDatabase2"); mongo.getDatabase("myDatabase3"); System.out.println("Databases created successfully"); } }OutputDatabases created successfully
Read MoreHow to drop an index in MongoDB using Java?
In MongoDB to drop an index, you need to use dropIndex() method.Syntaxdb.COLLECTION_NAME.dropIndex({KEY:1})In Java, you can drop an Index using the dropIndex() method, to this method you need to pass the type of the index (ascending or descending) and the field name on which you have created it.dropIndex(Indexes.ascending("name"));Exampleimport com.mongodb.client.MongoCollection; import com.mongodb.client.MongoDatabase; import com.mongodb.client.model.Indexes; import org.bson.Document; import com.mongodb.MongoClient; public class DroppingIndex { public static void main( String args[] ) { //Creating a MongoDB client MongoClient mongo = new MongoClient( "localhost" , 27017 ); //Accessing the database MongoDatabase database = ...
Read MoreExplain Java MongoDB projections
While retrieving data from MongoDb collections you can select only necessary data using projections. In Java, you can project necessary data while reading the documents from a collection using the projection() method. Invoke this method on the result of find(), bypassing the names of the required filed names as −projection(Projections.include("name", "age"));ExampleFollowing Java examples read the documents from a collection, using projection we are displaying the values of name and age fields only.import com.mongodb.client.FindIterable; import com.mongodb.client.MongoCollection; import com.mongodb.client.MongoDatabase; import com.mongodb.client.model.Projections; import java.util.ArrayList; import java.util.Iterator; import java.util.List; import org.bson.Document; import com.mongodb.MongoClient; public class ProjectionExample { public static void main( String args[] ...
Read MoreHow to display OpenCV Mat object using Swings?
The class ImageIcon is an implementation of the Icon interface that paints Icons from Images. You can display images on a Swing window using this class, the constructor of this class accepts a BufferedImage object as a parameter.Therefore to display an OpenCV image that is stored in a Mat object using Swing window, you need to convert it into a BufferedImage object and pass it as a parameter to the ImageIcon method.Exampleimport java.awt.image.BufferedImage; import java.io.ByteArrayInputStream; import java.io.InputStream; import javax.imageio.ImageIO; import javax.swing.ImageIcon; import javax.swing.JFrame; import javax.swing.JLabel; import org.opencv.core.Core; import org.opencv.core.Mat; import org.opencv.core.MatOfByte; import org.opencv.imgcodecs.Imgcodecs; public class DisplayingImagesUsingSwings { public static ...
Read MoreHow to display OpenCV Mat object using JavaFX?
The JavaFX library provides a class with name ImageView using this you can display an image. This class accepts an object of the WritableImage class.To display an image Stored in OpenCV Mat object you need to convert it into a WritableImage object and pass it the ImageView class.Exampleimport java.awt.image.BufferedImage; import java.io.ByteArrayInputStream; import java.io.IOException; import java.io.InputStream; import javafx.application.Application; import javafx.embed.swing.SwingFXUtils; import javafx.scene.Group; import javafx.scene.Scene; import javafx.scene.image.ImageView; import javafx.scene.image.WritableImage; import javafx.stage.Stage; import javax.imageio.ImageIO; import org.opencv.core.Core; import org.opencv.core.Mat; import org.opencv.core.MatOfByte; import org.opencv.imgcodecs.Imgcodecs; public class DisplayingImagesJavaFX extends Application { @Override public void start(Stage stage) throws IOException { WritableImage writableImage = ...
Read MoreWhat is the importance of jmod format in Java 9?
Java 9 has introduced a new format called "jmod" to encapsulate modules. The jmod files can be designed to handle more content types than jar files. It can also package local codes, configuration files, local commands, and other types of data. The "jmod" format hasn't support at runtime and can be based on zip format currently. The jmod format can be used at both compile and link time and can be found in JDK_HOME\jmods directory, where JDK_HOME is a directory. The files in jmod format have a ".jmod" extension.Java 9 comes with a new tool called jmod, and it is located in the ...
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