拍照返回的bitmap太小

private void doPhoto(int requestCode)
	{
		if(!Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)){
			showToast(this, "请插入SD存储卡");
			return;
		}
		Intent i = new Intent("android.media.action.IMAGE_CAPTURE");
		picPath = Environment.getExternalStorageDirectory() + "/" + System.currentTimeMillis() + ".png";
		File file = new File(picPath);
		Uri imageUri = Uri.fromFile(file);
		i.putExtra(MediaStore.EXTRA_OUTPUT, imageUri);

		startActivityForResult(i, requestCode);
	}

protected void onActivityResult(int requestCode, int resultCode, Intent data) {

		this.data = data;

		switch (requestCode) {

		case RequestCode_Camera_Self:// 自拍照
			if (resultCode == Activity.RESULT_OK)
			{
				File file = new File(picPath);

				Bitmap bmp = createImageThumbnail(picPath,400);
				byte[] datas = bitmap2Bytes(bmp,
						CompressFormat.JPEG);
				tfPhoto.setProperty("text", datas);
				tfPhoto.setImageBitmap(bmp); // 设置照片现实在界面上
				file.delete();
			}
			return;