code: public static int getCacheSize(Context ctx) {
  		final DisplayMetrics displayMetrics = ctx.getResources().
  				getDisplayMetrics();
  		final int screenWidth = displayMetrics.widthPixels;
  		final int screenHeight = displayMetrics.heightPixels;
  		// 4 bytes per pixel
  		final int screenBytes = screenWidth * screenHeight * 4;
  
  		return screenBytes * 3;
  	}
docs: Returns a cache size equal to approximately three screens worth of images.