imageprocessingproject.ImageHistogram.java Source code

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Here is the source code for imageprocessingproject.ImageHistogram.java

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package imageprocessingproject;

import java.awt.Color;
import java.awt.image.BufferedImage;
import org.jfree.chart.ChartFactory;
import org.jfree.chart.ChartPanel;
import org.jfree.chart.JFreeChart;
import org.jfree.chart.plot.PlotOrientation;
import org.jfree.data.xy.XYSeries;
import org.jfree.data.xy.XYSeriesCollection;

/**
 *
 * @author chamod
 */
public class ImageHistogram {
    private static double[] histogram;

    private static double[] contrast_lut;

    public static BufferedImage normalizeImage(BufferedImage image) {
        int height = image.getHeight();
        int width = image.getWidth();

        int r, g, b, minr = 255, ming = 255, minb = 255, maxr = 0, maxg = 0, maxb = 0;
        Color c;

        BufferedImage tempImage = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);

        for (int i = 0; i < width; i++) {
            for (int j = 0; j < height; j++) {
                c = new Color(image.getRGB(i, j));
                if (minr > c.getRed()) {
                    minr = c.getRed();
                }
                if (ming > c.getGreen()) {
                    ming = c.getGreen();
                }
                if (minb > c.getBlue()) {
                    minb = c.getBlue();
                }
                if (maxr < c.getRed()) {
                    maxr = c.getRed();
                }
                if (maxg < c.getGreen()) {
                    maxg = c.getGreen();
                }
                if (maxb < c.getBlue()) {
                    maxb = c.getBlue();
                }
            }
        }

        for (int i = 0; i < width; i++) {
            for (int j = 0; j < height; j++) {
                c = new Color(image.getRGB(i, j));
                r = (int) ((c.getRed() - minr) * 255 / (maxr - minr));
                g = (int) ((c.getGreen() - ming) * 255 / (maxg - ming));
                b = (int) ((c.getBlue() - minb) * 255 / (maxb - minb));
                tempImage.setRGB(i, j, new Color(r, g, b, c.getAlpha()).getRGB());
            }
        }

        return tempImage;
    }

    public static BufferedImage autoContrastImage(BufferedImage image) {
        createContrastLUT(image);

        int height = image.getHeight();
        int width = image.getWidth();
        int r, g, b;
        Color c;

        BufferedImage tempImage = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);

        for (int i = 0; i < width; i++) {
            for (int j = 0; j < height; j++) {
                c = new Color(image.getRGB(i, j));
                r = (int) (255 * contrast_lut[c.getRed()]);
                g = (int) (255 * contrast_lut[c.getGreen()]);
                b = (int) (255 * contrast_lut[c.getBlue()]);
                tempImage.setRGB(i, j, new Color(r, g, b, c.getAlpha()).getRGB());
            }
        }

        return tempImage;
    }

    private static void createContrastLUT(BufferedImage image) {
        createHistogram(image);
        contrast_lut = new double[256];

        double cumulative_prob = 0;
        for (int i = 0; i < 256; i++) {
            cumulative_prob += histogram[i];
            contrast_lut[i] = cumulative_prob;
        }
    }

    public static void printHistogram(BufferedImage image) {
        createHistogram(image);
        System.out.println("Histogram : ");
        for (int i = 0; i < 256; i++) {
            System.out.println(histogram[i]);
        }
    }

    private static void createHistogram(BufferedImage image) {
        histogram = new double[256];
        int height = image.getHeight();
        int width = image.getWidth();

        int sum = 0;
        for (int i = 0; i < width; i++) {
            for (int j = 0; j < height; j++) {
                int grayVal = getGrayValue(image.getRGB(i, j));
                histogram[grayVal]++;
                sum++;
            }
        }

        for (int i = 0; i < 256; i++) {
            histogram[i] = histogram[i] / sum;
        }

    }

    private static int getGrayValue(int rgb) {
        Color c = new Color(rgb);
        return (c.getRed() + c.getGreen() + c.getBlue()) / 3;
    }

    public static JFreeChart plotHistogram(BufferedImage image) {
        createHistogram(image);

        final XYSeries series = new XYSeries("Histogram Data");

        for (int i = 0; i < histogram.length; i++) {
            series.add(i, histogram[i]);
        }

        final XYSeriesCollection data = new XYSeriesCollection(series);
        final JFreeChart chart = ChartFactory.createXYLineChart("Image Histogram", "intensity", "PDF", data,
                PlotOrientation.VERTICAL, true, true, false);

        return chart;
    }
}