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Java Articles
Page 329 of 450
How 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 ...
Read MoreWhat are the different "/types" commands in JShell in Java 9?
JShell tool has introduced in Java 9 version. It is also called a REPL(Read-Evaluate-Print-Loop) tool that allows us to execute Java code and getting immediate results. We need to list out the declared types like class, interface, enum, and etc by using the "/types" command.Below are the different "/types" commands in JShell./types /types [ID] /types [Type_Name] /types -start /types -all/types: This command lists all active types (class, interface, enum) created in JShell./types [ID]: This command displays the type corresponding to the id [ID]./types [Type_Name]: This command displays the type corresponding to [Type_Name]./types -start: This command allows us to list the ...
Read MoreHow to convert a positive image to Negative to using OpenCV library?
Algorithm to convert an image to negativeGet the red green blue values of each pixelSubtract each color value from 255 and save them as new color values.Create a new pixel value from the modified colors.set the new value to the pixel.Implementation in JavaRead the required image using ImageIO.read() method.Get the height and width of the image.Using nested for loops traverse through each pixel in the image.Get the pixel value using the getRGB() method.Create a Color object bypassing the above-retrieved pixel value as parameter.Get the red, green, blue values from the color object using the getRed(), getGreen() and getBlue() methods respectively.Calculate ...
Read MoreWhen to use the ServiceLoader class in a module in Java 9?
Java has a ServiceLoader class from java.util package that can help to locate service providers at the runtime by searching in the classpath. For service providers defined in modules, we can look at the sample application to declare modules with service and how it works.For instance, we have a "test.app" module that we need to use Logger that can be retrieved from System.getLogger() factory method with the help of LoggerFinder service.module com.tutorialspoint.test.app { requires java.logging; exports com.tutorialspoint.platformlogging.app; uses java.lang.System.LoggerFinder; }Below is the test.app.MainApp class:package com.tutorialspoint.platformlogging.app; public class MainApp { ...
Read MoreHow to display different list commands in JShell in Java 9?
JShell has introduced in Java 9 and is a command-line tool that allows us to enter simple statements, expressions, methods, and classes without a main () method.When we can enter code in JShell, the code has assigned a unique ID. This ID starts at 1 and has incremented for each command entered in JShell. The same can be true for libraries loaded at startup. For each of these imports, a unique ID has been assigned. It starts with $1 and is incremented for each code loaded ($2, $3 and etc). There is an internal command to list all code loaded, and ...
Read MoreExplain the Mat class in Java OpenCV library
In OpenCV, images are stored in Using Mat object. It is nothing but an n-dimensional array and is used to store image data of grayscale or color images, voxel volumes, vector fields, point clouds, tensors, histograms, etc.If you try to read an image using the OpenCV library it will be read to a Mat object.Mat matrix = Imgcodecs.imread(filePath);You can instantiate this class manually using one of the following constructors −Mat() − A no-arg constructor, used to create an empty matrix and pass this to other OpenCV methods.Mat(int rows, int cols, int type) − This constructor accepts three parameters of integer ...
Read MoreHow to create custom color maps in Java using OpenCV?
The applyColorMap() method of the Imgproc class applies specified color map to the given image. This method accepts three parameters −Two Mat objects representing the source and destination images.An integer variable representing the type of the color map to be applied.You can pass any of the following as color map value to this method.COLORMAP_AUTUMN, COLORMAP_BONE, COLORMAP_COOL, COLORMAP_HOT, COLORMAP_HSV, COLORMAP_JET, COLORMAP_OCEAN , COLORMAP_PARULA, COLORMAP_PINK, COLORMAP_RAINBOW, COLORMAP_SPRING, COLORMAP_SUMMER, COLORMAP_WINTER.Exampleimport org.opencv.core.Core; import org.opencv.core.Mat; import org.opencv.imgcodecs.Imgcodecs; import org.opencv.imgproc.Imgproc; public class CustomColorMaps { public static void main(String args[]) { // Loading the OpenCV core library System.loadLibrary(Core.NATIVE_LIBRARY_NAME); ...
Read MoreHow to alter the brightness of a grey scale image?
The equalizeHist() method of the Imgproc class accepts a greyscale image and equalizes its histogram, which will, in turn, normalizes the brightness and increases the contrast of the given image. This method accepts two parameters −A Mat object representing the source image (greyscale).A Mat object to save the result.ExampleFollowing Java program reads a colored image as greyscale, saves it, normalizes the brightness and increases the contrast of the given image and saves it.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 HstExample { public static void main(String args[]) { //Loading the OpenCV core ...
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