import java.util.*;

import java.awt.*;

import java.awt.event.*;

import java.awt.image.*;

import java.awt.geom.*;

import java.io.*;

import javax.imageio.*;

// Main class

public class ImageHistogram extends Frame implements ActionListener {

BufferedImage input;

int width, height;

TextField texRad, texThres;

ImageCanvas source, target;

PlotCanvas plot;

// Constructor

public ImageHistogram(String name) {

super("Image Histogram");

// load image

try {

input =

ImageIO.read(newFile(name));

}

catch ( Exception ex ) {

ex.printStackTrace();

}

width = input.getWidth();

height = input.getHeight();

// prepare the panel for image canvas.

Panel main = new Panel();

source = new ImageCanvas(input);

plot = new PlotCanvas();

target = new ImageCanvas(input);

main.setLayout(new GridLayout(1, 3, 10, 10));

main.add(source);

main.add(plot);

main.add(target);

// prepare the panel for buttons.

Panel controls = new Panel();

Button button = new Button("Display Histogram");

button.addActionListener(this);

controls.add(button);

button = new Button("Histogram Stretch");

button.addActionListener(this);

controls.add(button);

controls.add(new Label("Cutoff fraction:"));

texThres = new TextField("10", 2);

controls.add(texThres);

button = new Button("Aggressive Stretch");

button.addActionListener(this);

controls.add(button);

button = new Button("Histogram Equalization");

button.addActionListener(this);

controls.add(button);

// add two panels

add("Center", main);

add("South", controls);

addWindowListener(new ExitListener());

setSize(width*2+400, height+100);

setVisible(true);

}

class ExitListener extends WindowAdapter {

public void windowClosing(WindowEvent e) {

System.exit(0);

}

}

// Action listener for button click events

public void actionPerformed(ActionEvent e) {

//compute the average color for the image

public void actionPerformed(ActionEvent e) {

//compute the average color for the image

int gray_level=256;

LineSegment redArr[] = new LineSegment[256];

if ( ((Button)e.getSource()).getLabel().equals("Display Histogram") ) {

int redArray[] = new int[256];

int greenArray[] = new int[256];

int blueArray[] = new int[256];

//int[gray_level];

float red=0, green=0, blue=0;

for (int q=0; q

for (int p=0; p

Color c = new Color(input.getRGB(p,q));

redArray[c.getRed()]++;

//greenArray[c.getGreen()]++;

//blueArray[c.getBlue()]++;

}

for(int i=0; i<255; i++){

redArr[i] = new LineSegment(Color.RED, i, redArray[i], i+1, redArray[i+1]);

}

plot.setMeanColor(redArr);

}

}

public static void main(String[] args) {

new ImageHistogram(args.length==1 ? args[0] : "baboo.png");

}

}

// Canvas for plotting histogram

class PlotCanvas extends Canvas {

// lines for plotting axes and mean color locations

LineSegment x_axis, y_axis;

LineSegment red, green, blue;

boolean showMean = false;

public PlotCanvas() {

x_axis = new LineSegment(Color.BLACK, -10, 0, 256+10, 0);

y_axis = new LineSegment(Color.BLACK, 0, -10, 0, 200+10);

}

// set mean image color for plot

public void setMeanColor(LineSegment[] array) {

for(int x=0; x<255; x++){

red = array[x];

showMean = true;

}

repaint();

}

// redraw the canvas

public void paint(Graphics g) {

// draw axis

int xoffset = (getWidth() - 256) / 2;

int yoffset = (getHeight() - 200) / 2;

x_axis.draw(g, xoffset, yoffset, getHeight());

y_axis.draw(g, xoffset, yoffset, getHeight());

if(showMean == true){

for(int h =0; h<255; h++){

red.draw(g, xoffset, yoffset, getHeight());

}

}

}

}

// LineSegment class defines line segments to be plotted

class LineSegment {

// location and color of the line segment

int x0, y0, x1, y1;

Color color;

// Constructor

public LineSegment(Color clr, int x0, int y0, int x1, int y1) {

color = clr;

this.x0 = x0; this.x1 = x1;

this.y0 = y0; this.y1 = y1;

}

public void draw(Graphics g, int xoffset, int yoffset, int height) {

g.setColor(color);

g.drawLine(x0+xoffset, height-y0-yoffset, x1+xoffset, height-y1-yoffset);

}

import java.awt.*;

import java.awt.event.*;

import java.awt.image.*;

import java.io.*;

import javax.imageio.*;

// Canvas for image display

class ImageCanvas extends Canvas {

BufferedImage image;

// initialize the image and mouse control

public ImageCanvas(BufferedImage input) {

image = input;

addMouseListener(new ClickListener());

}

// redraw the canvas

public void paint(Graphics g) {

// draw boundary

g.setColor(Color.gray);

g.drawRect(0, 0, getWidth()-1, getHeight()-1);

// compute the offset of the image.

int xoffset = (getWidth() - image.getWidth()) / 2;

int yoffset = (getHeight() - image.getHeight()) / 2;

g.drawImage(image, xoffset, yoffset, this);

}

// change the image and redraw the canvas

public void resetImage(Image input) {

image = new BufferedImage(input.getWidth(null), input.getHeight(null), BufferedImage.TYPE_INT_RGB);

Graphics2D g2D = image.createGraphics();

g2D.drawImage(input, 0, 0, null);

repaint();

}

// listen to mouse click

class ClickListener extends MouseAdapter {

public void mouseClicked(MouseEvent e) {

if ( e.getClickCount() == 2 && e.getButton() == MouseEvent.BUTTON3 )

try {

ImageIO.write(image, "png", new File("saved.png"));

} catch ( Exception ex ) {

ex.printStackTrace();

}

}

}

}

Trying to print out the LineSegment array on the display when an RGB image is input. I'm using this image: https://imgur.com/a/LwaYf

}