/**
   * Method to blur the pixels
   * @param numPixels the number of pixels to average in all
   * directions.  So if the numPixels is 2 then we will average
   * all pixels in the rectangle defined by 2 before the current
   * pixel to 2 after the current pixel
   */
  public void blur(int numPixels)
  {
    double starttime = System.currentTimeMillis();

    Pixel pixel = null;
    Pixel samplePixel = null;
    int redValue = 0;
    int greenValue = 0;
    int blueValue = 0;
    int count = 0;

    // loop through the pixels
    for (int x=0; x < this.getWidth(); x++) {
      for (int y=0; y < this.getHeight(); y++) {

        // get the current pixel
        pixel = this.getPixel(x,y);

        // reset the count and red, green, and blue values
        count = 0;
        redValue = greenValue = blueValue = 0;

        // loop through pixel numPixels before x to numPixels after x
        for (int xSample = x - numPixels;
             xSample <= x + numPixels;
             xSample++) {
          for (int ySample = y - numPixels;
               ySample <= y + numPixels;
               ySample++) {

            // check that we are in the range of acceptable pixels
            if (xSample >= 0 && xSample < this.getWidth() &&
                ySample >= 0 && ySample < this.getHeight()) {
              samplePixel = this.getPixel(xSample,ySample);
              redValue = redValue + samplePixel.getRed();
              greenValue = greenValue + samplePixel.getGreen();
              blueValue = blueValue + samplePixel.getBlue();
              count = count + 1;
            }
          }
        }

        // use average color of surrounding pixels
        Color newColor = new Color(redValue / count,
                                   greenValue / count,
                                   blueValue / count);
        pixel.setColor(newColor);
      }
    }
    double finishtime = System.currentTimeMillis();
    double executiontime = finishtime=starttime;
    System.out.println("Funktionen använde " + executiontime + " ms");
  }