Convolve1

import java.awt.image.*;
import java.awt.color.*;
import java.io.*;
import javax.imageio.*;
import javax.swing.JFrame;


public class Convolve {
int mask[][];
int scl;
boolean scale, bipolar;
boolean bipolar2 = false;
int mr, mc;
BufferedImage img;
int h1, w1;

public Convolve(int mask[][])
{
   this.mask = mask;
   mr = mask.length;
   mc = mask[0].length;
   scale = false;
   bipolar = false;
   scl = 0;
}

public void setScale(int scl)
{
   this.scl = scl;
   scale = true;
}

public void setBipolar(boolean bipolar)
{
   this.bipolar = bipolar;
}

public void getLine( int row, int dst[])
{
   int  v, r, g, b;
   //System.out.format("row %d%n",row);
   img.getRGB(0, row, w1, 1, dst, 0, w1);
   for (int i = 0; i < w1; i++) {
     v = dst[i];
     r = (v >> 16) & 0xFF;
     g = (v >> 8) & 0xFF;
     b = v & 0xFF;
     v = (r + g + b) / 3; // gray by averaging the pixels
     dst[i] = v;
   }
}

public void showMatrix(int v[][], String cmt)
{
   int i, j;
   int nrow = v.length;
   int ncol = v[0].length;
   System.out.format("%n%s%n%n",cmt);
   for (j=0; j<nrow; j++) {
      for (i=0; i<ncol; i++) {
               System.out.format("%3d ",v[j][i]);
      }
      System.out.format("%n");
   }
}

public BufferedImage doConvolve(BufferedImage in)
{
   int i, j, i1, j1, sum, v, midr, midc;
   int r, g, b, c;
   img = in;
   w1 = img.getWidth();
   h1 = img.getHeight();	
   int maxr = h1 - 1;
   int maxc = w1 - 1;

   int type = BufferedImage.TYPE_INT_RGB;
   BufferedImage outp = new BufferedImage(w1, h1, type);


   int data[][] = new int[mr][w1];
   int val[] = new int[w1];
   midr = mr/2;
   midc = mc/2;
   for (j=midr; j<mr; j++) getLine(j-midr,data[j]);
   for (j=0; j<midr; j++) System.arraycopy(data[midr],0,data[j],0,data[j].length);
   //System.out.println("start main loop ...");
   int row = mr - midr;
   for (j=0; j<h1; j++) {
      for (i=0; i<w1; i++) {
	   sum = 0;
           for (j1=0; j1<mr; j1++) {
              for (i1=0; i1<mc; i1++) {
                c = i + i1 - midr;
		try {
		  v = data[j1][c];
		}
		catch(ArrayIndexOutOfBoundsException e) {
		  if (c<0) v = data[j1][0];
		  else v = data[j1][maxc];
                }
		sum = sum + mask[j1][i1]*v;
              }
           }
           if (scale) sum /= scl;
	
           if (bipolar) sum = (sum+256)/2;
	
           r = g = b = sum;

	   if (bipolar2) {
		v = sum;
	        //g = data[midr][i];
                g = 0;
                if (v>0) {
                    r=v; b=0;
	        }
                else { r=0; b=-v; };
           }
           val[i] = 0xFF000000 | (r << 16) | (g << 8) | b;
      } 
      outp.setRGB(0, j, w1, 1, val, 0, w1);
      int [] swp;
      swp = data[0];
      for (j1=1; j1<mr; j1++) data[j1-1] = data[j1];

      if (row<h1) {
         data[mr-1] = swp;
         getLine(row++,data[mr-1]);
      }

   }
   return outp;
}
    public static void main(String [] args) {

	String filename = "test3.png";
	if (args.length>0) filename = args[0];

	showImage f1 = new showImage(filename);
	f1.setLocation(10,10);
	f1.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
	int w = f1.getWidth();
	int h = f1.getHeight();
	listImage.listGray(f1.img,filename);
	//int mask[][] = { {-1, 0, 1},{-2, 0, 2},{-1, 0, 1} };
	//int mask[][] = { {0, 0, 1}, {0, 0, 0}, {0, 0, 0} };;
	int mask[][] = new int[5][5];
	mask[1][3] = 1;
	Convolve c = new Convolve(mask);
	c.showMatrix(mask,"convolution mask");
	BufferedImage outp = c.doConvolve(f1.img);
	showImage f2 = new showImage(outp,"gray version");
	f2.setLocation(20+w,10);
	f2.writeImage("out1","png");
	listImage.listGray(f2.img,"filtered image");
		
    }
}