Add Java and Python code for the following tutorials:
- Changing the contrast and brightness of an image!
- Operations with images
This commit is contained in:
catree
+86
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import java.util.Scanner;
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import org.opencv.core.Core;
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import org.opencv.core.Mat;
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import org.opencv.highgui.HighGui;
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import org.opencv.imgcodecs.Imgcodecs;
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class BasicLinearTransforms {
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private byte saturate(double val) {
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int iVal = (int) Math.round(val);
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iVal = iVal > 255 ? 255 : (iVal < 0 ? 0 : iVal);
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return (byte) iVal;
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}
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public void run(String[] args) {
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/// Read image given by user
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//! [basic-linear-transform-load]
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String imagePath = args.length > 0 ? args[0] : "../data/lena.jpg";
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Mat image = Imgcodecs.imread(imagePath);
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if (image.empty()) {
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System.out.println("Empty image: " + imagePath);
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System.exit(0);
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}
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//! [basic-linear-transform-load]
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//! [basic-linear-transform-output]
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Mat newImage = Mat.zeros(image.size(), image.type());
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//! [basic-linear-transform-output]
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//! [basic-linear-transform-parameters]
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double alpha = 1.0; /*< Simple contrast control */
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int beta = 0; /*< Simple brightness control */
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/// Initialize values
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System.out.println(" Basic Linear Transforms ");
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System.out.println("-------------------------");
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try (Scanner scanner = new Scanner(System.in)) {
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System.out.print("* Enter the alpha value [1.0-3.0]: ");
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alpha = scanner.nextDouble();
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System.out.print("* Enter the beta value [0-100]: ");
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beta = scanner.nextInt();
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}
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//! [basic-linear-transform-parameters]
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/// Do the operation newImage(i,j) = alpha*image(i,j) + beta
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/// Instead of these 'for' loops we could have used simply:
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/// image.convertTo(newImage, -1, alpha, beta);
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/// but we wanted to show you how to access the pixels :)
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//! [basic-linear-transform-operation]
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byte[] imageData = new byte[(int) (image.total()*image.channels())];
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image.get(0, 0, imageData);
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byte[] newImageData = new byte[(int) (newImage.total()*newImage.channels())];
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for (int y = 0; y < image.rows(); y++) {
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for (int x = 0; x < image.cols(); x++) {
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for (int c = 0; c < image.channels(); c++) {
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double pixelValue = imageData[(y * image.cols() + x) * image.channels() + c];
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/// Java byte range is [-128, 127]
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pixelValue = pixelValue < 0 ? pixelValue + 256 : pixelValue;
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newImageData[(y * image.cols() + x) * image.channels() + c]
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= saturate(alpha * pixelValue + beta);
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}
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}
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}
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newImage.put(0, 0, newImageData);
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//! [basic-linear-transform-operation]
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//! [basic-linear-transform-display]
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/// Show stuff
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HighGui.imshow("Original Image", image);
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HighGui.imshow("New Image", newImage);
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/// Wait until user press some key
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HighGui.waitKey();
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//! [basic-linear-transform-display]
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System.exit(0);
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}
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}
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public class BasicLinearTransformsDemo {
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public static void main(String[] args) {
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// Load the native OpenCV library
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System.loadLibrary(Core.NATIVE_LIBRARY_NAME);
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new BasicLinearTransforms().run(args);
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}
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}
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+202
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import java.awt.BorderLayout;
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import java.awt.Container;
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import java.awt.Image;
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import java.awt.event.ActionEvent;
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import java.awt.event.ActionListener;
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import javax.swing.BoxLayout;
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import javax.swing.ImageIcon;
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import javax.swing.JCheckBox;
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import javax.swing.JFrame;
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import javax.swing.JLabel;
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import javax.swing.JPanel;
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import javax.swing.JSlider;
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import javax.swing.event.ChangeEvent;
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import javax.swing.event.ChangeListener;
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import org.opencv.core.Core;
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import org.opencv.core.CvType;
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import org.opencv.core.Mat;
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import org.opencv.highgui.HighGui;
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import org.opencv.imgcodecs.Imgcodecs;
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class ChangingContrastBrightnessImage {
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private static int MAX_VALUE_ALPHA = 500;
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private static int MAX_VALUE_BETA_GAMMA = 200;
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private static final String WINDOW_NAME = "Changing the contrast and brightness of an image demo";
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private static final String ALPHA_NAME = "Alpha gain (contrast)";
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private static final String BETA_NAME = "Beta bias (brightness)";
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private static final String GAMMA_NAME = "Gamma correction";
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private JFrame frame;
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private Mat matImgSrc = new Mat();
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private JLabel imgSrcLabel;
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private JLabel imgModifLabel;
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private JPanel controlPanel;
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private JPanel alphaBetaPanel;
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private JPanel gammaPanel;
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private double alphaValue = 1.0;
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private double betaValue = 0.0;
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private double gammaValue = 1.0;
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private JCheckBox methodCheckBox;
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private JSlider sliderAlpha;
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private JSlider sliderBeta;
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private JSlider sliderGamma;
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public ChangingContrastBrightnessImage(String[] args) {
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String imagePath = args.length > 0 ? args[0] : "../data/lena.jpg";
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matImgSrc = Imgcodecs.imread(imagePath);
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if (matImgSrc.empty()) {
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System.out.println("Empty image: " + imagePath);
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System.exit(0);
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}
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// Create and set up the window.
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frame = new JFrame(WINDOW_NAME);
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frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
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// Set up the content pane.
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Image img = HighGui.toBufferedImage(matImgSrc);
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addComponentsToPane(frame.getContentPane(), img);
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// Use the content pane's default BorderLayout. No need for
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// setLayout(new BorderLayout());
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// Display the window.
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frame.pack();
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frame.setVisible(true);
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}
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private void addComponentsToPane(Container pane, Image img) {
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if (!(pane.getLayout() instanceof BorderLayout)) {
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pane.add(new JLabel("Container doesn't use BorderLayout!"));
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return;
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}
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controlPanel = new JPanel();
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controlPanel.setLayout(new BoxLayout(controlPanel, BoxLayout.PAGE_AXIS));
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methodCheckBox = new JCheckBox("Do gamma correction");
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methodCheckBox.addActionListener(new ActionListener() {
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@Override
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public void actionPerformed(ActionEvent e) {
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JCheckBox cb = (JCheckBox) e.getSource();
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if (cb.isSelected()) {
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controlPanel.remove(alphaBetaPanel);
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controlPanel.add(gammaPanel);
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performGammaCorrection();
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frame.revalidate();
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frame.repaint();
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frame.pack();
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} else {
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controlPanel.remove(gammaPanel);
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controlPanel.add(alphaBetaPanel);
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performLinearTransformation();
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frame.revalidate();
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frame.repaint();
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frame.pack();
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}
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}
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});
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controlPanel.add(methodCheckBox);
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alphaBetaPanel = new JPanel();
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alphaBetaPanel.setLayout(new BoxLayout(alphaBetaPanel, BoxLayout.PAGE_AXIS));
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alphaBetaPanel.add(new JLabel(ALPHA_NAME));
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sliderAlpha = new JSlider(0, MAX_VALUE_ALPHA, 100);
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sliderAlpha.setMajorTickSpacing(50);
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sliderAlpha.setMinorTickSpacing(10);
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sliderAlpha.setPaintTicks(true);
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sliderAlpha.setPaintLabels(true);
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sliderAlpha.addChangeListener(new ChangeListener() {
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@Override
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public void stateChanged(ChangeEvent e) {
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alphaValue = sliderAlpha.getValue() / 100.0;
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performLinearTransformation();
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}
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});
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alphaBetaPanel.add(sliderAlpha);
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alphaBetaPanel.add(new JLabel(BETA_NAME));
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sliderBeta = new JSlider(0, MAX_VALUE_BETA_GAMMA, 100);
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sliderBeta.setMajorTickSpacing(20);
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sliderBeta.setMinorTickSpacing(5);
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sliderBeta.setPaintTicks(true);
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sliderBeta.setPaintLabels(true);
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sliderBeta.addChangeListener(new ChangeListener() {
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@Override
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public void stateChanged(ChangeEvent e) {
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betaValue = sliderBeta.getValue() - 100;
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performLinearTransformation();
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}
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});
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alphaBetaPanel.add(sliderBeta);
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controlPanel.add(alphaBetaPanel);
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gammaPanel = new JPanel();
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gammaPanel.setLayout(new BoxLayout(gammaPanel, BoxLayout.PAGE_AXIS));
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gammaPanel.add(new JLabel(GAMMA_NAME));
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sliderGamma = new JSlider(0, MAX_VALUE_BETA_GAMMA, 100);
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sliderGamma.setMajorTickSpacing(20);
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sliderGamma.setMinorTickSpacing(5);
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sliderGamma.setPaintTicks(true);
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sliderGamma.setPaintLabels(true);
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sliderGamma.addChangeListener(new ChangeListener() {
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@Override
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public void stateChanged(ChangeEvent e) {
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gammaValue = sliderGamma.getValue() / 100.0;
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performGammaCorrection();
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}
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});
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gammaPanel.add(sliderGamma);
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pane.add(controlPanel, BorderLayout.PAGE_START);
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JPanel framePanel = new JPanel();
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imgSrcLabel = new JLabel(new ImageIcon(img));
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framePanel.add(imgSrcLabel);
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imgModifLabel = new JLabel(new ImageIcon(img));
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framePanel.add(imgModifLabel);
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pane.add(framePanel, BorderLayout.CENTER);
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}
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private void performLinearTransformation() {
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Mat img = new Mat();
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matImgSrc.convertTo(img, -1, alphaValue, betaValue);
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imgModifLabel.setIcon(new ImageIcon(HighGui.toBufferedImage(img)));
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frame.repaint();
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}
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private byte saturate(double val) {
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int iVal = (int) Math.round(val);
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iVal = iVal > 255 ? 255 : (iVal < 0 ? 0 : iVal);
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return (byte) iVal;
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}
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private void performGammaCorrection() {
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//! [changing-contrast-brightness-gamma-correction]
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Mat lookUpTable = new Mat(1, 256, CvType.CV_8U);
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byte[] lookUpTableData = new byte[(int) (lookUpTable.total()*lookUpTable.channels())];
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for (int i = 0; i < lookUpTable.cols(); i++) {
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lookUpTableData[i] = saturate(Math.pow(i / 255.0, gammaValue) * 255.0);
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}
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lookUpTable.put(0, 0, lookUpTableData);
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Mat img = new Mat();
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Core.LUT(matImgSrc, lookUpTable, img);
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//! [changing-contrast-brightness-gamma-correction]
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imgModifLabel.setIcon(new ImageIcon(HighGui.toBufferedImage(img)));
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frame.repaint();
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}
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}
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public class ChangingContrastBrightnessImageDemo {
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public static void main(String[] args) {
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// Load the native OpenCV library
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System.loadLibrary(Core.NATIVE_LIBRARY_NAME);
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// Schedule a job for the event dispatch thread:
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// creating and showing this application's GUI.
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javax.swing.SwingUtilities.invokeLater(new Runnable() {
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@Override
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public void run() {
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new ChangingContrastBrightnessImage(args);
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}
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});
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}
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}
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import java.util.Arrays;
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import org.opencv.core.Core;
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import org.opencv.core.Core.MinMaxLocResult;
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import org.opencv.core.CvType;
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import org.opencv.core.Mat;
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import org.opencv.core.Rect;
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import org.opencv.highgui.HighGui;
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import org.opencv.imgcodecs.Imgcodecs;
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import org.opencv.imgproc.Imgproc;
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public class MatOperations {
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@SuppressWarnings("unused")
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public static void main(String[] args) {
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/* Snippet code for Operations with images tutorial (not intended to be run) */
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// Load the native OpenCV library
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System.loadLibrary(Core.NATIVE_LIBRARY_NAME);
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String filename = "";
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// Input/Output
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{
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//! [Load an image from a file]
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Mat img = Imgcodecs.imread(filename);
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//! [Load an image from a file]
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}
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{
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//! [Load an image from a file in grayscale]
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Mat img = Imgcodecs.imread(filename, Imgcodecs.IMREAD_GRAYSCALE);
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//! [Load an image from a file in grayscale]
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}
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{
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Mat img = new Mat(4, 4, CvType.CV_8U);
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//! [Save image]
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Imgcodecs.imwrite(filename, img);
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//! [Save image]
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}
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// Accessing pixel intensity values
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{
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Mat img = new Mat(4, 4, CvType.CV_8U);
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int y = 0, x = 0;
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{
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//! [Pixel access 1]
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byte[] imgData = new byte[(int) (img.total() * img.channels())];
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img.get(0, 0, imgData);
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byte intensity = imgData[y * img.cols() + x];
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//! [Pixel access 1]
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}
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{
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//! [Pixel access 5]
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byte[] imgData = new byte[(int) (img.total() * img.channels())];
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imgData[y * img.cols() + x] = (byte) 128;
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img.put(0, 0, imgData);
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//! [Pixel access 5]
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}
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}
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// Memory management and reference counting
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{
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//! [Reference counting 2]
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Mat img = Imgcodecs.imread("image.jpg");
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Mat img1 = img.clone();
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//! [Reference counting 2]
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}
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{
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//! [Reference counting 3]
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Mat img = Imgcodecs.imread("image.jpg");
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Mat sobelx = new Mat();
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Imgproc.Sobel(img, sobelx, CvType.CV_32F, 1, 0);
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//! [Reference counting 3]
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}
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// Primitive operations
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{
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Mat img = new Mat(400, 400, CvType.CV_8UC3);
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{
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//! [Set image to black]
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byte[] imgData = new byte[(int) (img.total() * img.channels())];
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Arrays.fill(imgData, (byte) 0);
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img.put(0, 0, imgData);
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//! [Set image to black]
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}
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{
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//! [Select ROI]
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Rect r = new Rect(10, 10, 100, 100);
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Mat smallImg = img.submat(r);
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//! [Select ROI]
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}
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}
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{
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//! [BGR to Gray]
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Mat img = Imgcodecs.imread("image.jpg"); // loading a 8UC3 image
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Mat grey = new Mat();
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Imgproc.cvtColor(img, grey, Imgproc.COLOR_BGR2GRAY);
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//! [BGR to Gray]
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}
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{
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Mat dst = new Mat(), src = new Mat();
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//! [Convert to CV_32F]
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src.convertTo(dst, CvType.CV_32F);
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//! [Convert to CV_32F]
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}
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// Visualizing images
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{
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//! [imshow 1]
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Mat img = Imgcodecs.imread("image.jpg");
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HighGui.namedWindow("image", HighGui.WINDOW_AUTOSIZE);
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HighGui.imshow("image", img);
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HighGui.waitKey();
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//! [imshow 1]
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}
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{
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//! [imshow 2]
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Mat img = Imgcodecs.imread("image.jpg");
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Mat grey = new Mat();
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Imgproc.cvtColor(img, grey, Imgproc.COLOR_BGR2GRAY);
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Mat sobelx = new Mat();
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Imgproc.Sobel(grey, sobelx, CvType.CV_32F, 1, 0);
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MinMaxLocResult res = Core.minMaxLoc(sobelx); // find minimum and maximum intensities
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Mat draw = new Mat();
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double maxVal = res.maxVal, minVal = res.minVal;
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sobelx.convertTo(draw, CvType.CV_8U, 255.0 / (maxVal - minVal), -minVal * 255.0 / (maxVal - minVal));
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HighGui.namedWindow("image", HighGui.WINDOW_AUTOSIZE);
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HighGui.imshow("image", draw);
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HighGui.waitKey();
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//! [imshow 2]
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}
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System.exit(0);
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}
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}
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