我正在计算图像红色分量的直方图并将其存储在 redhisto[] 中。数组的索引代表强度(0到255)
该值表示具有该强度的像素数。然后使用 JFreeChart 绘制这些值。
我的问题是:
- 如何让X轴的值从0开始。现在是从负数开始。
-
Can we change the color of the bars in the graph
code is :
public class Histogram extends ApplicationFrame {
public Histogram(final String title) throws IOException {
super(title);
IntervalXYDataset dataset = createDataset();
JFreeChart chart = createChart(dataset);
final ChartPanel chartPanel = new ChartPanel(chart);
chartPanel.setPreferredSize(new java.awt.Dimension(500, 270));
setContentPane(chartPanel);
}
private IntervalXYDataset createDataset() throws IOException {
BufferedImage imageA = ImageIO.read(new File("XYZ.bmp"));
int[] red = new int[imageA.getHeight()*imageA.getWidth()];
int[] redhisto = new int[256];
int[] pixel;
int k= 0;
for (int y = 0; y < imageA.getHeight(); y++) {
for (int x = 0; x < imageA.getWidth(); x++) {
pixel = imageA.getRaster().getPixel(x, y, new int[3]);
red[k] = pixel[0];
k++;
}
}
for(int x=0;x<red.length;x++){
int y = red[x];
redhisto[y]++;
}
final XYSeries series = new XYSeries("No of pixels");
for(int i=0; i<redhisto.length;i++)
series.add(i,redhisto[i]);
final XYSeriesCollection dataset = new XYSeriesCollection(series);
return dataset;
}
private JFreeChart createChart(IntervalXYDataset dataset) {
final JFreeChart chart = ChartFactory.createXYBarChart("Color Intensity Histogram","X",false,"Y",dataset,PlotOrientation.VERTICAL,true,true,false);
XYPlot plot = (XYPlot) chart.getPlot();
return chart;
}
public static void main(final String[] args) throws IOException {
final Histogram demo = new Histogram("Image Histogram");
demo.pack();
RefineryUtilities.centerFrameOnScreen(demo);
demo.setVisible(true);
}
}
您可以更改域轴的下限并设置系列绘制,如下所示。默认XYBarPainter
有渐变色高亮,所以我用了StandardXYBarPainter
.
XYPlot plot = (XYPlot) chart.getPlot();
ValueAxis axis = plot.getDomainAxis();
axis.setLowerBound(0);
XYBarRenderer r = (XYBarRenderer) plot.getRenderer();
r.setBarPainter(new StandardXYBarPainter());
r.setSeriesPaint(0, Color.blue);
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