Line detection using Hough Transform

[syarizma]

hi..
Here, the code to convert the image into binary(Binary_image.java).Now, i need help to code the program for line detection of the binary image .

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.awt.image.*;
import java.awt.Image.*;



public class Binary_Image extends JApplet{
 
    	Image img;
    	int iw,ih;
    	int pixels[];
    	int cnt1=0,cnt=0,cnt2=0;
    	
    	public void init()
        {
        	try
            	{
            	
            	ImageIcon imageIcon = new ImageIcon("jawi.gif");
            	Image img = imageIcon.getImage();
            		
            		iw = img.getWidth(null);
            		ih = img.getHeight(null);
            		
            		pixels = new int[iw*ih];
            		PixelGrabber pg = new PixelGrabber(img,0,0,iw,ih,pixels,0,iw);
            		pg.grabPixels();
 
            	} catch(InterruptedException e) {};
            
            	for(int i=0;i<iw*ih;i++)
                {
                	int p = pixels[i];
                	int r = (p>>16) & 0xff;
                	int g = (p>>8) & 0xff;
                	int b = (p) & 0xff;
                	int k = (int)(.56*g + .33*r + .11 * b);
                
                	cnt++;
                			if(k<36)
                    			{
                    				cnt1++;
                    				pixels[i]=(255 << 24)|(0 << 16)|(0 << 8)|0;
                    			}
                    			else
                        			{
                        				cnt2++;
                        				pixels[i]=(255 << 24)|(255 << 16)|(255 << 8)|255;
                        			}
                        		}	
                        		//System.out.println("Total no of pixels ="+cnt);
                        		System.out.println("Total no of black pixels ="+cnt1);
                        		//System.out.println("Total no of white pixels ="+cnt2);
                        
                        		img = createImage(new MemoryImageSource(iw,ih,pixels,0,iw));
                                //double [][]ImgArr =new double[50][50] ;        
    }
    
    public static void main(String[]args) 
    	{
    		JFrame frame = new JFrame ();
    		
    		Binary_Image applet = new Binary_Image();
    		
    		frame.add(applet,BorderLayout.CENTER);
    		
    		applet.init();
    		
    		frame.setSize(500,300);
    		frame.setLocationRelativeTo(null);
    		frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    		frame.setVisible(false);
      }   
}

The algorithm as follows:

1.0 Define the Hough Transform ρmin, ρmax, θmin, and θmax.
2.0 Quantify the ρ-θ plane into cells by formatting an accumulator cells array A(ρ,θ) where ρ is between ρmin and ρmax and θ is between θmin to θmax.
3.0 Initialize each element of an accumulator cell array A to zero.
4.0 For each black pixel in a binary image, perform the following:
4.1 For each value of θ from θmin to θmax , calculate the corresponding ρ using equation:
ρ = x cos θ + y sin θ
4.2 Round off the ρ value to the nearest interval value.
4.3 Increment the accumulator array element A (ρ, θ).
4.4 Detect best line candidates as local maxima in an accumulator cell array.