Android อยากทราบวิธีการจัดการ Memory โหลดรูปภาพจาก web server แล้วไม่ Out of memory

public static Bitmap loadBitmap(String url) {
	    bitmap = null;
	    InputStream in = null;
	    BufferedOutputStream out = null;

	    try {
	    	BitmapFactory.Options options = new BitmapFactory.Options();
	    	options.inJustDecodeBounds = true;
	    	BitmapFactory.decodeStream(new URL(url).openStream(),null,options);
	    	//use your required height and width in place of 80 (size of imageview maybe)
	    	options.inSampleSize = calculateInSampleSize(options,80, 80); 
	    	options.inJustDecodeBounds = false;
	    	bitmap = BitmapFactory.decodeStream(new URL(url).openStream(),null,options);
	        
	    } catch (IOException e) {
	        Log.e(TAG, "Could not load Bitmap from: " + url);
	    } finally {
	        closeStream(in);
	        closeStream(out);
	    }

	    return bitmap;
	}
	
	public static int calculateInSampleSize(BitmapFactory.Options options,
	        int reqWidth, int reqHeight) {
	    // Raw height and width of image
	    final int height = options.outHeight;
	    final int width = options.outWidth;
	    int inSampleSize = 1;

	    if (height > reqHeight || width > reqWidth) {
	        if (width > height) {
	            inSampleSize = Math.round((float) height / (float) reqHeight);
	        } else {
	            inSampleSize = Math.round((float) width / (float) reqWidth);
	        }
	    }
	    return inSampleSize;
	}