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Histogram equalization on an image in OpenCV using Java.
The histogram of an image shows the frequency of pixels’ intensity values. In an image histogram, the X-axis shows the gray level intensities and the Y-axis shows the frequency of these intensities and improves the contrast of an image.
The equalizeHist() method of the Imgproc method accepts to Mat objects representing the source and destination images, equalizes the histogram of the source matrix and receives it in the destination matrix.
Example
import java.awt.Image;
import java.awt.image.BufferedImage;
import java.io.IOException;
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 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 HistogramEquilization extends Application {
public void start(Stage stage) throws IOException {
//Loading the OpenCV core library
System.loadLibrary( Core.NATIVE_LIBRARY_NAME );
String file ="D:\Images\win2.jpg";
Mat src = Imgcodecs.imread(file, Imgcodecs.IMREAD_GRAYSCALE);
//Creating an empty matrices to store the destination image.
Mat dst = new Mat(src.rows(), src.cols(), src.type());
//Detecting the edges
Imgproc.equalizeHist(src, dst);
//Converting matrix to JavaFX writable image
Image img = HighGui.toBufferedImage(dst);
WritableImage writableImage= SwingFXUtils.toFXImage((BufferedImage) img, null);
//Setting the image view
ImageView imageView = new ImageView(writableImage);
imageView.setX(10);
imageView.setY(10);
imageView.setFitWidth(575);
imageView.setPreserveRatio(true);
//Setting the Scene object
Group root = new Group(imageView);
Scene scene = new Scene(root, 595, 400);
stage.setTitle("Histogram Equilization Example");
stage.setScene(scene);
stage.show();
}
public static void main(String args[]) {
launch(args);
}
}Input Image
Output
On executing, the above produces the following output −
Updated on: 13-Apr-2020
455 Views
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