Java显示图像数据的直方图

下面的示例使用多种技术来创建任意图像的RGB直方图：

• 该

  Raster

  方法

  getSamples()

  从中提取每个色带的值BufferedImage。

• 该

  HistogramDataset

  方法

  addSeries()

  将每个频段的计数添加到

  dataset

  。

• 一个

  StandardXYBarPainter

  替换

  ChartFactory

  默认，如图所示这里。

• 定制

  DefaultDrawingSupplier

  提供每个系列所需的颜色；它包含半透明的颜色。

• 一种变型

  VisibleAction

  ，讨论在这里，用于控制每个带的可见性; 这里

  ChartMouseListener

  显示了一种补充方法。

import java.awt.BorderLayout;import java.awt.Color;import java.awt.EventQueue;import java.awt.Paint;import java.awt.event.ActionEvent;import java.awt.image.BufferedImage;import java.awt.image.Raster;import java.io.IOException;import java.net.URL;import javax.imageio.ImageIO;import javax.swing.AbstractAction;import javax.swing.ImageIcon;import javax.swing.JCheckBox;import javax.swing.Jframe;import javax.swing.JLabel;import javax.swing.JPanel;import org.jfree.chart.ChartFactory;import org.jfree.chart.ChartPanel;import org.jfree.chart.JFreeChart;import org.jfree.chart.plot.DefaultDrawingSupplier;import org.jfree.chart.plot.PlotOrientation;import org.jfree.chart.plot.XYPlot;import org.jfree.chart.renderer.xy.StandardXYBarPainter;import org.jfree.chart.renderer.xy.XYBarRenderer;import org.jfree.data.statistics.HistogramDataset;public class Histogram {    private static final int BINS = 256;    private final BufferedImage image = getImage();    private HistogramDataset dataset;    private XYBarRenderer renderer;    private BufferedImage getImage() {        try { return ImageIO.read(new URL(     "http://i.imgur.com/kxXhIH1.jpg"));        } catch (IOException e) { e.printStackTrace(System.err);        }        return null;    }    private ChartPanel createChartPanel() {        // dataset        dataset = new HistogramDataset();        Raster raster = image.getRaster();        final int w = image.getWidth();        final int h = image.getHeight();        double[] r = new double[w * h];        r = raster.getSamples(0, 0, w, h, 0, r);        dataset.addSeries("Red", r, BINS);        r = raster.getSamples(0, 0, w, h, 1, r);        dataset.addSeries("Green", r, BINS);        r = raster.getSamples(0, 0, w, h, 2, r);        dataset.addSeries("Blue", r, BINS);        // chart        JFreeChart chart = ChartFactory.createHistogram("Histogram", "Value", "Count", dataset, PlotOrientation.VERTICAL, true, true, false);        XYPlot plot = (XYPlot) chart.getPlot();        renderer = (XYBarRenderer) plot.getRenderer();        renderer.setBarPainter(new StandardXYBarPainter());        // translucent red, green & blue        Paint[] paintArray = { new Color(0x80ff0000, true), new Color(0x8000ff00, true), new Color(0x800000ff, true)        };        plot.setDrawingSupplier(new DefaultDrawingSupplier( paintArray, DefaultDrawingSupplier.DEFAULT_FILL_PAINT_SEQUENCE, DefaultDrawingSupplier.DEFAULT_OUTLINE_PAINT_SEQUENCE, DefaultDrawingSupplier.DEFAULT_STROKE_SEQUENCE, DefaultDrawingSupplier.DEFAULT_OUTLINE_STROKE_SEQUENCE, DefaultDrawingSupplier.DEFAULT_SHAPE_SEQUENCE));        ChartPanel panel = new ChartPanel(chart);        panel.setMouseWheelEnabled(true);        return panel;    }    private JPanel createControlPanel() {        JPanel panel = new JPanel();        panel.add(new JCheckBox(new VisibleAction(0)));        panel.add(new JCheckBox(new VisibleAction(1)));        panel.add(new JCheckBox(new VisibleAction(2)));        return panel;    }    private class VisibleAction extends AbstractAction {        private final int i;        public VisibleAction(int i) { this.i = i; this.putValue(NAME, (String) dataset.getSeriesKey(i)); this.putValue(SELECTED_KEY, true); renderer.setSeriesVisible(i, true);        }        @Override        public void actionPerformed(ActionEvent e) { renderer.setSeriesVisible(i, !renderer.getSeriesVisible(i));        }    }    private void display() {        Jframe f = new Jframe("Histogram");        f.setDefaultCloseOperation(Jframe.EXIT_ON_CLOSE);        f.add(createChartPanel());        f.add(createControlPanel(), BorderLayout.SOUTH);        f.add(new JLabel(new ImageIcon(image)), BorderLayout.WEST);        f.pack();        f.setLocationRelativeTo(null);        f.setVisible(true);    }    public static void main(String[] args) {        EventQueue.invokeLater(() -> { new Histogram().display();        });    }}