The org.opencv.imgproc package of Java OpenCV library contains a class named Imgproc. To draw a rectangle you need to invoke the rectangle() method of this class. This method accepts the following parameters −A Mat object representing the image on which the rectangle is to be drawn.Two Point objects representing the vertices of the rectangle that is to be drawn.A Scalar object representing the color of the rectangle(BGR).An integer representing the thickness of the rectangle(default:1).Exampleimport org.opencv.core.Core; import org.opencv.core.Mat; 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 DrawingRectangle {    public static void main(String args[]) {     ... Read More

The org.opencv.imgproc package of Java OpenCV library contains a class named Imgproc. To draw an ellipse you need to invoke the ellipse() method of this class. This method accepts the following parameters −A Mat object representing the image on which the ellipse is to be drawn.A RotatedRect object (The ellipse is drawn inscribed in this rectangle.)A Scalar object representing the color of the Rectangle(BGR).An integer representing the thickness of the Rectangle(default:1).Exampleimport org.opencv.core.Core; import org.opencv.core.Mat; import org.opencv.core.Point; import org.opencv.core.RotatedRect; import org.opencv.core.Scalar; import org.opencv.core.Size; import org.opencv.highgui.HighGui; import org.opencv.imgcodecs.Imgcodecs; import org.opencv.imgproc.Imgproc; public class DrawingEllipse {    public static void main(String args[]) {   ... Read More

The org.opencv.imgproc package of Java OpenCV library contains a class named Imgproc. To draw a line you need to invoke the line() method of this class. This method accepts the following parameters −A Mat object representing the image on which the line is to be drawn.Two Point objects representing the points between which the line is to be drawn.A Scalar object representing the color of the line. (BGR)An integer representing the thickness of the line(default:1).Exampleimport org.opencv.core.Core; import org.opencv.core.Mat; 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 DrawingLine {    Mat matrix = null;    public static ... Read More

You can convert HLS image to RGB (colored) image by passing Imgproc.COLOR_RGB2HLS as the 3rd parameter to the cvtColor() method.Exampleimport org.opencv.core.Core; import org.opencv.core.Mat; import org.opencv.imgcodecs.Imgcodecs; import org.opencv.imgproc.Imgproc; public class HSL2RGB {    public static void main(String args[]) throws Exception {       System.loadLibrary( Core.NATIVE_LIBRARY_NAME );       Mat src = Imgcodecs.imread("D:\images\car3.jpg");       Mat dst = new Mat();       Imgproc.cvtColor(src, dst, Imgproc.COLOR_RGB2HLS);       Imgcodecs imageCodecs = new Imgcodecs();       imageCodecs.imwrite("D:\images\hslImage.jpg", dst);       System.out.println("Image Saved");    } }InputOutput

The cvtColor() method of the Imgproc class changes/converts the color of the image from one to another. This method accepts three parameters −src − A Matrix object representing source.dst − A Matrix object representing the destination.code − An integer value representing the color of the destination image.You can convert a colored image to an HLS image by passing Imgproc.COLOR_RGB2HLS as a parameter to the above method.Exampleimport org.opencv.core.Core; import org.opencv.core.Mat; import org.opencv.imgcodecs.Imgcodecs; import org.opencv.imgproc.Imgproc; public class RGB2HSL {    public static void main(String args[]) throws Exception {       //Loading the OpenCV core library       System.loadLibrary( Core.NATIVE_LIBRARY_NAME ); ... Read More

The cvtColor() method of the Imgproc class changes/converts the color of the image from one to another. This method accepts three parameters −src − A Matrix object representing source.dst − A Matrix object representing the destination.code − An integer value representing the color of the destination image.To convert an HSV image to BGR you need to pass Imgproc.COLOR_HSV2BGR as the 3rd parameter to the cvtColor() method.Examplepublic class HSV2RGB {    public static void main(String args[]) throws Exception {       System.loadLibrary( Core.NATIVE_LIBRARY_NAME );       Mat src = Imgcodecs.imread("D:\images\hsvimage2.jpg");       Mat dst = new Mat();     ... Read More

The cvtColor() method of the Imgproc class changes/converts the color of the image from one to another. This method accepts three parameters −src − A Matrix object representing source.dst − A Matrix object representing the destination.code − An integer value representing the color of the destination image.To convert an HSV image to RGB you need to pass Imgproc.COLOR_HSV2RGB as the third parameter to this method.Exampleimport org.opencv.core.Core; import org.opencv.core.Mat; import org.opencv.imgcodecs.Imgcodecs; import org.opencv.imgproc.Imgproc; public class HSV2RGB {    public static void main(String args[]) throws Exception {       //Loading the OpenCV core library       System.loadLibrary( Core.NATIVE_LIBRARY_NAME );     ... Read More

The cvtColor() method of the Imgproc class changes/converts the color of the image from one to another. This method accepts three parameters −src − A Matrix object representing source.dst − A Matrix object representing the destination.code − An integer value representing the color of the destination image.To convert an RGB image to HSV you need to pass Imgproc.COLOR_RGB2HSV as the third parameter to this method.Exampleimport org.opencv.core.Core; import org.opencv.core.Mat; import org.opencv.imgcodecs.Imgcodecs; import org.opencv.imgproc.Imgproc; public class RGB2HSV {    public static void main(String args[]) throws Exception {       //Loading the OpenCV core library       System.loadLibrary( Core.NATIVE_LIBRARY_NAME );   ... Read More

Sharpening an image is the opposite of blur. To alter the sharpness of an image using the OpenCV library, you need to smooth/blur it using the Gaussian filter and subtract the smoothed version from the original image.ExampleFollowing is a JavaFX program with two sliders representing the alpha and beta values.import java.awt.image.BufferedImage; import java.io.ByteArrayInputStream; import java.io.IOException; import java.io.InputStream; import javafx.application.Application; import javafx.beans.value.ChangeListener; import javafx.beans.value.ObservableValue; import javafx.embed.swing.SwingFXUtils; import javafx.geometry.Insets; import javafx.scene.Scene; import javafx.scene.control.Label; import javafx.scene.control.Slider; import javafx.scene.image.ImageView; import javafx.scene.image.WritableImage; import javafx.scene.layout.VBox; 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.core.Size; import org.opencv.imgcodecs.Imgcodecs; import org.opencv.imgproc.Imgproc; public class SharpnessJavaFX extends Application ... Read More

The convertTo() method of the org.opencv.core.Mat class accepts 4 parameters namely: mat(empty matrix), rtype(integer), alpha(integer), beta(integer), in the same order.To increase the brightness − You need to reduce the beta value from 0 towards -255(keeping alpha value 1).To decrease the brightness − You need to increase the beta value from 0 towards 255(keeping alpha value 1).To increase the contrast − You need to increase the alpha value from 1 towards 100(keeping beta value 0).To decrease the contrast − You need to decrease the alpha value from 1 to 0 (keeping beta value 0).ExampleFollowing is a JavaFX program with two slide ... Read More