Java Image Processing

String process(File file, int width, int height) throws IOException {
   BufferedImage img = ImageIO.read(file);
   int px = img.getWidth()/width;
   int py = img.getHeight()/height;

   StringBuilder bits = new StringBuilder();
   for(int r = 0; r < height; r++)
      for(int c = 0; c < width; c++)
         bits.append(bw(img.getRGB(c*px + px/2, r*py + py/2)));

   char[] bytes = new char[bits.length()/8];
   for(int i = 0; i < bytes.length; i++)
      bytes[i] = (char)Integer.parseInt(bits.substring(8*i,8*i+8),2);

   return String.copyValueOf(bytes);
}

int bw(int rgb){
   return (rgb >>> 16 & 255) + (rgb >>> 8 & 255) + (rgb & 255) > 3*255/2 ? 0 : 1;
}