Pixel leftPixel = null;
    Pixel rightPixel = null;
    Pixel[][] pixels = this.getPixels2D();
    Color rightColor = null;
    for (int row = 0; row < pixels.length; row++)
    {
      for (int col = 0;
           col < pixels[0].length-1; col++)
      {
        leftPixel = pixels[row][col];
        rightPixel = pixels[row][col+1];
        rightColor = rightPixel.getColor();
        if (leftPixel.colorDistance(rightColor) >
            edgeDist)
          leftPixel.setColor(Color.BLACK);
        else
          leftPixel.setColor(Color.WHITE);
      }
    }
  }