This Java program performs optical character recognition (OCR) on image files. It allows the user to open an image file, then perform line, word, and character segmentation on the image. The program displays the original image and overlay lines, words, and character boxes as each segmentation step is performed. It uses histograms and thresholding techniques on the pixel data to identify lines, words, and characters in the image.

1. import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.JOptionPane;
import java.io.*;
import java.util.*;
import java.awt.image.*;
public class ocr extends JFrame
{
JTextField m_fileNameTF = new JTextField(15);
JFileChooser m_fileChooser = new JFileChooser();
DrawingPanel imagepanel;
private JMenuItem menu;
JavaFilter fJavaFilter;
int mouseX,mouseY,mx,my;
Image img;
int flag=3;
int clear;
int flag3=0;
int flag4=0;
int flag5=0;
seg myseg = new seg();

2. public static void main(String[] args)
{
ocr window = new ocr();
window.setVisible(true);
}
// constructor
ocr()
{
// set the Text field to Read Only mode
m_fileNameTF.setEditable(false);
// Choose only files, not directories
m_fileChooser.setFileSelectionMode ( JFileChooser.FILES_ONLY);
// Set filter for Java source files.
fJavaFilter = new JavaFilter();
m_fileChooser.setFileFilter (fJavaFilter);
//... create Button and its listeners
JButton openButton = new JButton("Open");
JButton lineButton = new JButton("line segment");
JButton wordButton=new JButton("word segment");

3. JButton charButton=new JButton("char segment");
JButton clearButton=new JButton("clear");
//setting tool tips for various buttons
openButton.setToolTipText("click here to choose a file");
lineButton.setToolTipText("click here for line segmentation");
wordButton.setToolTipText("click here for word segmentation");
charButton.setToolTipText("click here for char segmentation");
clearButton.setToolTipText("click here to clear the panel");
//adding mouse listener to various buttons
openButton.addActionListener(new OpenAction());
lineButton.addActionListener(new LineAction());
wordButton.addActionListener(new wordAction());
charButton.addActionListener(new charAction());
clearButton.addActionListener(new clearAction());
//... Create contant pane, layout components
JPanel content = new JPanel();
JMenuBar bar=new JMenuBar();
setJMenuBar(bar);
JMenu helpmenu=new JMenu("Help ...Alt+H");
helpmenu.setMnemonic('H');
JMenuItem aboutopen=new JMenuItem("About open. A.");
JMenuItem lineseg=new JMenuItem("Line segmentation L");
aboutopen.setMnemonic('A');
lineseg.setMnemonic('L');

4. aboutopen.addActionListener(
new ActionListener()
{
public void actionPerformed(ActionEvent e )
{
JOptionPane.showMessageDialog(null,"To load an image,click open");
}
}
);
lineseg.addActionListener(
new ActionListener()
{
public void actionPerformed(ActionEvent e )
{
JOptionPane.showMessageDialog(null,"To perform lines");
}
}
);
helpmenu.add(aboutopen);
helpmenu.add(lineseg);
content.setLayout(new BorderLayout());
JPanel buttonpanel=new JPanel();
buttonpanel.add(openButton);

5. buttonpanel.add(m_fileNameTF);
buttonpanel.add(lineButton);
buttonpanel.add(wordButton);
buttonpanel.add(charButton);
buttonpanel.add(clearButton);
content.add(helpmenu,"North");
content.add(buttonpanel,"South");
bar.add(helpmenu);
// Create JPanel canvas to hold the picture
imagepanel = new DrawingPanel();
//imagepanel.addMouseListener(new MouseClickListener());
// Create JScrollPane to hold the canvas containing the picture
JScrollPane scroller = new JScrollPane(
JScrollPane.VERTICAL_SCROLLBAR_ALWAYS,
JScrollPane.HORIZONTAL_SCROLLBAR_ALWAYS);
scroller.setPreferredSize(new Dimension(500,300));
scroller.setViewportView(imagepanel);
scroller.setViewportBorder(
BorderFactory.createLineBorder(Color.black));
// Add scroller pane to Panel

6. content.add(scroller,"Center");
//Set window characteristics
this.setTitle("File Browse and View");
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
this.setContentPane(content);
this.pack();
} //ocr contructor
class DrawingPanel extends JPanel
{
int x,y;
public DrawingPanel()
{
setBackground(Color.white);
setPreferredSize(new Dimension(750,950));
MouseClickListener listener= new MouseClickListener();
addMouseListener(listener);
Mouserelease listen=new Mouserelease();
addMouseListener(listen);
}

7. protected void paintComponent(Graphics g)
{
super.paintComponent(g);
if (img!=null && clear==0)
{
g.drawImage(img, 0, 0, this);
}
if(flag==0 && clear==0)
{ int x = 0;
while(myseg.line[x] != -1)
{
g.drawLine(0,myseg.line[x],img.getWidth(imagepanel),myseg.line[x]);
x++;
}
}
if(flag3==1)
{
for(int x=0;x<17;x++)
{ int y=0;
while(myseg.wordarr[x][y]!=-1)

8. {
g.drawLine(myseg.wordarr[x][y],myseg.line[2*x],myseg.wordarr[x]
[y],myseg.line[2*x+1]);
y++;
}
}
}
if(flag4==1)
{
int z;
int x = 0;
myseg.line[32]=-1;
while(myseg.line[2*x] != -1)
{
int y = 0;
while(myseg.wordarr[x][2*y] != -1)
{
z = 0;
while(myseg.carr[x][y][2*z] !=-1)
{
//System.out.println(x + " " + y + " " + 2*z + carr[x][y][2*z] + carr[x][y][2*z+1]);
g.drawRect(myseg.carr[x][y][2*z],myseg.line[2*x] + 11,myseg.carr[x][y][2*z+1]-myseg.carr[x]
[y][2*z],
myseg.line[2*x+1]-myseg.line[2*x]-11);

9. z++;
}
y++;
}
x++;
}
}
if(flag5==1)
{
int z;
int x = 0;
myseg.line[32]=-1;
while(myseg.line[2*x] != -1)
{
int y = 0;
while(myseg.wordarr[x][2*y] != -1)
{
z = 0;
while(myseg.carr[x][y][2*z] !=-1)
{
//System.out.println(x + " " + y + " " + 2*z + carr[x][y][2*z] + carr[x][y][2*z+1]);
g.drawRect(myseg.tarr[x][y][2*z],myseg.line[2*x], myseg.tarr[x][y][2*z+1]-myseg.tarr[x][y]
[2*z],
11);
z++;
}

10. y++;
}
x++;
}
}
}
public int linesegdriver()
{
int width=img.getWidth(imagepanel);
int height=img.getHeight(imagepanel);
int w=width;
int h=height;
int m = 0;
int hHisto[] = new int[h] ;
HHISTO(0, 0, w, h, hHisto);
m = myseg.lineseg(w, h, hHisto);
return m;
}
public int wordsegdriver(int lineno)

11. {
// System.out.println("In wordseg function");
int w = img.getWidth(imagepanel);
int h = myseg.line[2*lineno+1] - myseg.line[2*lineno];
int lnb = myseg.line[2*lineno];
int lne = myseg.line[2*lineno+1];
int vHisto[] = new int[w+1] ;
int m = 0;
VHISTO(0, lnb, w, h, vHisto);
m = myseg.wordseg(lineno, w, h, vHisto);
//PixelGrabber pg = new PixelGrabber (img,0,lnb,w,h, pixels,0,w);
// PixelGrabber pg = new PixelGrabber (img,0,lnb,w,lne-lnb, pixels,0,w);
//class wordAction implements ActionListener
return m;
}
public void charsegdriver(int ln, int wn)
{
if(myseg.wordarr[ln][2*wn] ==-1 )
{
myseg.carr[ln][wn][0]=-1;
return;

12. }
int w=myseg.wordarr[ln][2*wn+1]-myseg.wordarr[ln][2*wn];
int h=myseg.line[ln*2+1]-myseg.line[ln*2];
int hHisto[] = new int[h] ;
int hlinepos=-1;
HHISTO(myseg.wordarr[ln][2*wn], myseg.line[ln*2], w, h, hHisto);
hlinepos = myseg.hline(ln, wn, w, h, hHisto);
//System.out.println("hlinepos "+hlinepos);
flag3=1; flag4=1;flag5=1;
h=myseg.line[ln*2+1]-myseg.line[ln*2]-hlinepos-2;
int vHisto[] = new int[w+1] ;
VHISTO(myseg.wordarr[ln][wn*2], myseg.line[ln*2] +hlinepos+3, w, h, vHisto);
myseg.ccharseg(ln, wn, w, h, vHisto);
h=hlinepos-2;
VHISTO(myseg.wordarr[ln][wn*2], myseg.line[ln*2], w, h, vHisto);

13. myseg.tcharseg(ln, wn, w, h, vHisto);
//lcharseg(vHisto);
}//char
public void sethLine( )
{
repaint();
}
public void setvLine(int lineno, int nowords)
{
flag3=1;
repaint();
}
public void setRect(int lineno, int nowords)
{
flag4=1; flag3=0; flag5=1;
repaint();
}
void VHISTO(int x, int y, int w, int h, int vHisto[])
{
int pixels[] = new int [w*h] ;
int pix[][] = new int [h][w] ;

14. PixelGrabber pg = new PixelGrabber (img,x,y,w,h,pixels,0,w);
try
{
pg.grabPixels();
}
catch(InterruptedException ee)
{
}
for (int t = 0; t <w ; t++)
vHisto[t] = 0;
for( int i=0;i<w*h;i++)
{
int p= pixels[i] ;
int r = 0xff & (p>>16) ;
int g = 0xff & (p>>8);
int b = 0xff & (p);
if(r>=127 && g>=127&& b>=127)
pixels[i]=1;
else
pixels[i]=0;

15. }
int j= 0;
for(int m=0; m<h;m++)
{
for(int n=0;n<w;n++)
{
pix[m][n] = pixels[j] ;
if (pix[m][n]==0)
vHisto[n]=vHisto[n] + 1 ;
j++ ;
}
}
//for(int m=0;m<w;m++)
// System.out.println("vHisto= "+vHisto[m]);
return;
} //VHISTO
void HHISTO(int x, int y, int w, int h, int hHisto[])
{
int pixels[] = new int [w*h] ;
int pix[][] = new int [h][w] ;

16. PixelGrabber pg = new PixelGrabber (img,x,y,w,h,pixels,0,w);
try
{
pg.grabPixels();
}
catch(InterruptedException ee)
{
}
for (int t = 0; t <h ; t++)
hHisto[t] = 0;
for( int i=0;i<w*h;i++)
{
int p= pixels[i] ;
int r = 0xff & (p>>16) ;
int g = 0xff & (p>>8);
int b = 0xff & (p);
if(r>=127 && g>=127&& b>=127)
pixels[i]=1;
else
pixels[i]=0;

17. }
int j= 0;
for(int m=0; m<h;m++)
{
for(int n=0;n<w;n++)
{
pix[m][n] = pixels[j] ;
if (pix[m][n]==0)
hHisto[m]=hHisto[m] + 1 ;
j++ ;
}
}
//for(int m=0;m<h;m++)
// System.out.println("hHisto= "+hHisto[m]);
return;
} //HHISTO
} //drawing panel
class MouseClickListener extends MouseAdapter
{

18. public void mousePressed(MouseEvent e)
{
mouseX=e.getX();
mouseY=e.getY();
mx=mouseX;
my=mouseY;
}
}
class Mouserelease extends MouseAdapter
{
public void mouseReleased(MouseEvent e)
{
imagepanel.repaint();
}
}
// OpenAction
class OpenAction implements ActionListener
{
public void actionPerformed(ActionEvent ae)
{

19. //... Open a file dialog.
clear=0;
int retval = m_fileChooser.showOpenDialog(ocr.this);
if (retval == JFileChooser.APPROVE_OPTION)
{
//... The user selected a file, process it.
File file = m_fileChooser.getSelectedFile();
// store the file path in a string and send to JNI
String fPath = file.getPath();
System.out.println("The Path is:n" + fPath);
//... Update user interface.
img = Toolkit.getDefaultToolkit().getImage(file.getPath());
m_fileNameTF.setText(file.getName());
imagepanel.repaint();
}
}
}
//this tries to build lines
class LineAction implements ActionListener
{
public void actionPerformed(ActionEvent e)
{
int width = img.getWidth(imagepanel);

20. int height = img.getHeight(imagepanel);
flag=0;
//System.out.println("in line button");
int nolines = imagepanel.linesegdriver();
imagepanel.sethLine();
}
}
class wordAction implements ActionListener
{
public void actionPerformed(ActionEvent e)
{
int nowords = 0;
//System.out.println("in wordseg");
for(int i = 0; i < 17; i++)
{
nowords = imagepanel.wordsegdriver(i);
System.out.println("line" + i + "nowords" + nowords);
imagepanel.setvLine(i, nowords);
}
return;
}

21. }
class charAction implements ActionListener
{
public void actionPerformed(ActionEvent e)
{
for(int i = 0; i < 17; i++)
{
int j = 0;
while(myseg.wordarr[i][j*2] != -1)
{
//System.out.println("in charbox");
imagepanel.charsegdriver(i, j);
imagepanel.setRect(i, j);
j++;
}
}
return;
}
}
class clearAction implements ActionListener
{
public void actionPerformed(ActionEvent e)

22. {imagepanel.removeAll();
imagepanel.revalidate();
//System.out.println("in clear button");
clear=1;
flag3=0;
flag=1;
imagepanel.repaint();
}
}
/** Filter to work with JFileChooser to select java file types. **/
class JavaFilter extends javax.swing.filechooser.FileFilter
{
// this function is internally used for the Filtering action
public boolean accept (File f)
{
return f.getName ().toLowerCase ().endsWith (".jpeg")
|| f.getName ().toLowerCase ().endsWith (".jpg")
|| f.getName ().toLowerCase ().endsWith (".gif")
|| f.isDirectory ();
}
// this function is internally used for the Filter Option drop down menu

23. public String getDescription ()
{
return "*.jpeg, *.gif, *.jpg";
}
}
}