/*檢測模糊度 
 返回值為模糊度，值越大越模糊，越小越清晰，範圍在0到幾十，10以下相對較清晰，一般為5。
 呼叫時可在外部設定一個閥值，具體閾值根據實際情況決定，返回值超過閥值當作是模糊圖片。 
 演算法所耗時間在1毫秒內
*/
int VideoBlurDetect(const cv::Mat &srcimg)
{
	cv::Mat img;
	cv::cvtColor(srcimg, img, CV_BGR2GRAY); // 將輸入的圖片轉為灰度圖，使用灰度圖檢測模糊度

	//圖片每行位元組數及高  
	int width = img.cols;
	int height = img.rows;
	ushort* sobelTable = new ushort[width*height];
	memset(sobelTable, 0, width*height*sizeof(ushort));

	int i, j, mul;
	//指向影象首地址  
	uchar* udata = img.data;
	for (i = 1, mul = i*width; i < height - 1; i++, mul += width)
	for (j = 1; j < width - 1; j++)

		sobelTable[mul + j] = abs(udata[mul + j - width - 1] + 2 * udata[mul + j - 1] + udata[mul + j - 1 + width] - \
		udata[mul + j + 1 - width] - 2 * udata[mul + j + 1] - udata[mul + j + width + 1]);

	for (i = 1, mul = i*width; i < height - 1; i++, mul += width)
	for (j = 1; j < width - 1; j++)
	if (sobelTable[mul + j] < 50 || sobelTable[mul + j] <= sobelTable[mul + j - 1] || \
		sobelTable[mul + j] <= sobelTable[mul + j + 1]) sobelTable[mul + j] = 0;

	int totLen = 0;
	int totCount = 1;

	uchar suddenThre = 50;
	uchar sameThre = 3;
	//遍歷圖片  
	for (i = 1, mul = i*width; i < height - 1; i++, mul += width)
	{
		for (j = 1; j < width - 1; j++)
		{
			if (sobelTable[mul + j])
			{
				int   count = 0;
				uchar tmpThre = 5;
				uchar max = udata[mul + j] > udata[mul + j - 1] ? 0 : 1;

				for (int t = j; t > 0; t--)
				{
					count++;
					if (abs(udata[mul + t] - udata[mul + t - 1]) > suddenThre)
						break;

					if (max && udata[mul + t] > udata[mul + t - 1])
						break;

					if (!max && udata[mul + t] < udata[mul + t - 1])
						break;

					int tmp = 0;
					for (int s = t; s > 0; s--)
					{
						if (abs(udata[mul + t] - udata[mul + s]) < sameThre)
						{
							tmp++;
							if (tmp > tmpThre) break;
						}
						else break;
					}

					if (tmp > tmpThre) break;
				}

				max = udata[mul + j] > udata[mul + j + 1] ? 0 : 1;

				for (int t = j; t < width; t++)
				{
					count++;
					if (abs(udata[mul + t] - udata[mul + t + 1]) > suddenThre)
						break;

					if (max && udata[mul + t] > udata[mul + t + 1])
						break;

					if (!max && udata[mul + t] < udata[mul + t + 1])
						break;

					int tmp = 0;
					for (int s = t; s < width; s++)
					{
						if (abs(udata[mul + t] - udata[mul + s]) < sameThre)
						{
							tmp++;
							if (tmp > tmpThre) break;
						}
						else break;
					}

					if (tmp > tmpThre) break;
				}
				count--;

				totCount++;
				totLen += count;
			}
		}
	}
	//模糊度
	float result = (float)totLen / totCount;
	delete[] sobelTable;
	sobelTable = NULL;

	return result;
}