Can't use fisheye lens effect on my image in Java

Question 1

So I finally implemented desired fisheye! Just because of this and this site. I am giving here really messy but working code for anyone with similar problem:

package fisheye;

import java.awt.image.BufferedImage;
import java.awt.image.WritableRaster;
import java.io.File;
import java.io.IOException;
import javax.imageio.ImageIO;

public class DitherMain {

   static String imageString = "image.bmp";

   BufferedImage startImage, endImage;
   int[] startPixels, endPixels, imR, imG, imB;
   int width, height;

   public static void main(String[] args){
      new DitherMain(loadImage(imageString));
   }

   //this object transforms the old image and writes the new image
   DitherMain(BufferedImage img){
      //filing the image into startpixels
      startImage = img;
      width = img.getWidth();
      height = img.getHeight();
      startPixels = new int[width*height];
      img.getRGB(0, 0, width, height, startPixels, 0, width);

      endPixels = fisheye(startPixels, width, height);

      transformPixels();

      WritableRaster wRaster = endImage.getData().createCompatibleWritableRaster();

      wRaster.setSamples(0, 0, width, height, 0, imR);
      wRaster.setSamples(0, 0, width, height, 1, imG);
      wRaster.setSamples(0, 0, width, height, 2, imB);

      endImage.setData(wRaster);
      System.out.println(endImage);

      //writing the file for endImage into the harddrive
      writeFile();
   }

   void transformPixels(){
      //endPixels = startPixels;
      endImage = startImage;

      imR = new int[endPixels.length];
      imG = new int[endPixels.length];
      imB = new int[endPixels.length];

      for(int i = 0; i < endPixels.length; i++){
         imR[i] = (endPixels[i] >> 16) & 0x000000FF;
         imG[i] = (endPixels[i] >> 8) & 0x000000FF;
         imB[i] = endPixels[i] & 0x000000FF;
      }
   }

   void writeFile(){
      try {
         ImageIO.write(endImage,"BMP",new File("RESULT.bmp"));
      } catch (IOException e) {
         e.printStackTrace();
      }
   }

   //this method just loads a specific buffered image
   public static BufferedImage loadImage(String fileName){   
      BufferedImage img;

      try{
         img=ImageIO.read(new File("image.bmp"));
         //img = ImageIO.read(DitherMain.class.getResource(fileName));
      } catch (Exception e) {
         e.printStackTrace();
         throw new RuntimeException(e);
      }
      return img;
   }

public static int[] fisheye(int[] srcpixels, double w, double h) {

    /*
     *    Fish eye effect
     *    tejopa, 2012-04-29
     *    http://popscan.blogspot.com
     *    http://www.eemeli.de
     */

    // create the result data
    int[] dstpixels = new int[(int)(w*h)];            
    // for each row
    for (int y=0;y<h;y++) {                                
        // normalize y coordinate to -1 ... 1
        double ny = ((2*y)/h)-1;                        
        // pre calculate ny*ny
        double ny2 = ny*ny;                                
        // for each column
        for (int x=0;x<w;x++) {                            
            // normalize x coordinate to -1 ... 1
            double nx = ((2*x)/w)-1;                    
            // pre calculate nx*nx
            double nx2 = nx*nx;
            // calculate distance from center (0,0)
            // this will include circle or ellipse shape portion
            // of the image, depending on image dimensions
            // you can experiment with images with different dimensions
            double r = Math.sqrt(nx2+ny2);                
            // discard pixels outside from circle!
            if (0.0<=r&&r<=1.0) {                            
                double nr = Math.sqrt(1.0-r*r);            
                // new distance is between 0 ... 1
                nr = (r + (1.0-nr)) / 2.0;
                // discard radius greater than 1.0
                if (nr<=1.0) {
                    // calculate the angle for polar coordinates
                    double theta = Math.atan2(ny,nx);         
                    // calculate new x position with new distance in same angle
                    double nxn = nr*Math.cos(theta);        
                    // calculate new y position with new distance in same angle
                    double nyn = nr*Math.sin(theta);        
                    // map from -1 ... 1 to image coordinates
                    int x2 = (int)(((nxn+1)*w)/2.0);        
                    // map from -1 ... 1 to image coordinates
                    int y2 = (int)(((nyn+1)*h)/2.0);        
                    // find (x2,y2) position from source pixels
                    int srcpos = (int)(y2*w+x2);            
                    // make sure that position stays within arrays
                    if (srcpos>=0 & srcpos < w*h) {
                        // get new pixel (x2,y2) and put it to target array at (x,y)
                        dstpixels[(int)(y*w+x)] = srcpixels[srcpos];    
                    }
                }
            }
        }
    }
    //return result pixels
    return dstpixels;
}    

}

Question 2

Refer to this site:

http://popscan.blogspot.in/2012/04/fisheye-lens-equation-simple-fisheye.html

It contains the concept as well as working source at the end of the article.

Question 3

make your function static

public static BufferedImage barrel (BufferedImage input, float k)

and change

public static void main(String avg[]) throws IOException
{ 
    BufferedImage img=ImageIO.read(new File("image.jpg"));

    //now pass this image to your barrel method and return in new image
    //note that, method can be called now without instatntiating any object, as it is static now
    BufferImage barrelImage = barrel(img,2.0);       
    ImageIcon icon=new ImageIcon(barrelImage);   
    ...
    ...
}