Convolve.java

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


public class Convolve {
int mask[][];
int scl;
int bipolar_style=0;
boolean scale, bipolar;
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 setBipolarStyle(int set)
{
	bipolar_style = set;
	bipolar = true;
}

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];
   int vt[] = 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 - midc;
		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 (sum>255) sum = 255;
	   if (sum<-255) sum = -255;
	   r = g = b = sum;
	   vt[i] = sum;
           val[i] = 0xFF000000 | (r << 16) | (g << 8) | b;
      }
      if (bipolar) makeBipolar(vt,val);
      outp.setRGB(0, j, w1, 1, val, 0, w1);
      int [] swp;
      swp = data[0];
      for (int m=1; m<mr; m++) data[m-1] = data[m];
      if (row<h1) {
		getLine(row++,swp);
		data[mr-1] = swp;
      }
   }
   return outp;
}

   public void makeBipolar(int [] vin, int [] vout) {
	int r, g, b, v, sum;
	
           for (int i=0; i<vin.length; i++) {
		sum = vin[i];
		switch (bipolar_style) {
		case 0:
 
			sum = (sum+255)/2;
          		r = g = b = sum;
			break;
		case 1:
			v = sum;
			if (sum<0) v = -sum;
	               	r = g = b = 255;
			if (v>64) {
               	   		if (sum>0) {
                      			r=255; b=g=255-v;
	            		}
                    		else if (sum<0) { 
					r=g=255-v; b=255;; 
		    		}
			}
			break;
		case 2:
			v = sum;
			if (sum<0) v = -sum;
	        	//g = data[midr][i];
                	r = g = b = 255;
			if (v>64) {
               	   		if (sum>0) {
                      			r=v; b=g=0;
	            		}
                    		else if (sum<0){ 
					r=g=0; b=v;; 
		   		 }
			}
			break;
		default:
			sum = (sum+255)/2;
          		r = g = b = sum;
		}				
                vout[i] = 0xFF000000 | (r << 16) | (g << 8) | b;
	}
   }

}