Histogram Equalization for Color Images: Make Your Image More Clear

I have written histogram equalization tutorial with gray-scale images before. You can read that from here: http://terminalcoders.blogspot.in/2017/02/histogram-equalisation-in-java.html
The tutorial explains what is histogram equalization, algorithm and its implementation in Java. Here I'm not explaining anything about histogram equalization because already explained in that tutorial post. Only Java implementation code is sharing.

Source Code

import java.awt.GridLayout;
import java.awt.image.BufferedImage;
import java.awt.image.WritableRaster;
import java.io.File;
import javax.imageio.ImageIO;
import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import java.awt.*;


/**
 *
 * @author AJITH KP (http://fb.com/ajithkp560)
 * http://www.terminalcoders.blogspot.com
 * 
 */
public class HistogramEqualization extends JFrame{
    HistogramEqualization(String in, String out){
        super("..:: Histogram Equalization ::..");
        try {
            this.setLayout(new GridLayout(1, 2, 10, 10));
            JPanel img1 = new JPanel();
            JPanel img2 = new JPanel();
            File f1 = new File(in);
            File f2 = new File(out);
            BufferedImage image1 = ImageIO.read(f1);
            img1.add(new JLabel(new ImageIcon(image1)));
            BufferedImage image2 = equalize(image1);
            ImageIO.write(image2, "png", f2);
            img2.add(new JLabel(new ImageIcon(image2)));
            this.add(img1);
            this.add(img2);
        } catch (Exception ex) {
            System.out.println(ex.getMessage());
        }
    }
    BufferedImage equalize(BufferedImage src){
        BufferedImage nImg = new BufferedImage(src.getWidth(), src.getHeight(), src.getType());
        int[] hr = new int[256];
        int[] hg = new int[256];
        int[] hb = new int[256];
        int totpix = src.getWidth() * src.getHeight();

        for (int x = 0; x < src.getWidth(); x++) {
            for (int y = 0; y < src.getHeight(); y++) {
                Color c = new Color(src.getRGB(x, y));
                hr[c.getRed()]++;
                hg[c.getGreen()]++;
                hb[c.getBlue()]++;
            }
        }
        
        int[] chr = new int[256];
        int[] chg = new int[256];
        int[] chb = new int[256];
        chr[0] = hr[0];
        chg[0] = hg[0];
        chb[0] = hb[0];
        for(int i=1;i<256;i++){
            chr[i] = chr[i-1] + hr[i];
            chg[i] = chg[i-1] + hg[i];
            chb[i] = chb[i-1] + hb[i];
        }
        
        float[] arr = new float[256];
        float[] arg = new float[256];
        float[] arb = new float[256];
        for(int i=0;i<256;i++){
            arr[i] =  (float)((chr[i]*255.0)/(float)totpix);
            arg[i] =  (float)((chg[i]*255.0)/(float)totpix);
            arb[i] =  (float)((chb[i]*255.0)/(float)totpix);
        }
        
        for (int x = 0; x < src.getWidth(); x++) {
            for (int y = 0; y < src.getHeight(); y++) {
                Color c = new Color(src.getRGB(x, y));
                Color nc = new Color((int)arr[c.getRed()], (int)arg[c.getGreen()], (int)arb[c.getBlue()]);
                nImg.setRGB(x, y, nc.getRGB());
            }
        }
        return nImg;
    }
    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        System.out.println("#! TERMINALCODERS ::..\nhttp://www.terminalcoders.blogspot.com\nhttp://www.tctech.in");
        if(args.length<2){
            System.out.println("Usage: java HistogramEqualization <input file name> <output file name>");
        }
        else{
            HistogramEqualization he = new HistogramEqualization(args[0], args[1]);
            he.setSize(1024, 500);
            he.setVisible(true);
            he.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        }
    }
    
}