jashliao 用 VC++ 實現fanfuhan OpenCV 教學087 ~ opencv-087-視頻(影片)基於幀差法(前後畫面相減)實現移動對象偵測分析

資料來源: https://fanfuhan.github.io/

https://fanfuhan.github.io/2019/05/08/opencv-087/

GITHUB:https://github.com/jash-git/fanfuhan_ML_OpenCV

https://github.com/jash-git/jashliao-implements-FANFUHAN-OPENCV-with-VC

★前言:

★主題:
    光流跟踪與背景消除都是基於建模方式的視頻分析方法，其實這類方法最原始的一個例子就是對視頻移動對象的幀差法跟踪，這個在視頻分析與處理中也是一種很常見的手段，有時候會取得意想不到的好效果，幀差法進一步劃分有可以分為：

    ◇兩幀差

    ◇三幀差

    假設有當前幀frame，前一幀prev1，更前一幀prev2

        兩幀差方法直接使用前一幀減去當前幀diff = frame – prev1

        三幀差方法計算如下：
            diff1 = prev2 – prev1
            diff2 = frame – prev1
            diff = diff1 & diff2

    幀差法在求取幀差之前一般會進行高斯模糊，用以減低干擾，通過得到的diff圖像進行形態學操作，用以合併與候選區域，提升效率。

    幀差法的缺點有如下：

        高斯模糊是高耗時計算

        容易受到噪聲與光線干擾

★C++

// VC_FANFUHAN_OPENCV087.cpp : 定義主控台應用程式的進入點。
//
/*
// Debug | x32
通用屬性
| C/C++
|	| 一般
|		| 其他 Include 目錄 -> ..\..\opencv411_x64\include
|
| 連結器
| 	|一一般
|		|  其他程式庫目錄 -> ..\..\opencv411_x64\lib
|
| 	|一輸入
|		| 其他相依性 -> opencv_world411d.lib;%(AdditionalDependencies)
// Releas | x64
組態屬性
| C/C++
|	| 一般
|		| 其他 Include 目錄 -> ..\..\opencv411_x64\include;%(AdditionalDependencies)
|
| 連結器
| 	|一般
|		| 其他程式庫目錄 -> ..\..\opencv411_x64\lib;%(AdditionalDependencies)
|
| 	|一輸入
|		| 其他相依性 -> opencv_world411.lib;%(AdditionalDependencies)
*/

#include "stdafx.h"
#include <iostream>
#include <opencv2/opencv.hpp>
#include <opencv2/core/core.hpp>
#include <opencv2/highgui/highgui.hpp>

using namespace std;
using namespace cv;

void blur_demo(Mat &image, Mat &sum);
void edge_demo(Mat &image, Mat &sum);
int getblockSum(Mat &sum, int x1, int y1, int x2, int y2, int i);

void showHistogram(InputArray src, cv::String StrTitle);
void backProjection_demo(Mat &mat, Mat &model);
void blur3x3(Mat &src, Mat *det);

void add_salt_pepper_noise(Mat &image);
void add_gaussian_noise(Mat &image);

void USMImage(Mat src, Mat &usm, float fltPar);

void pyramid_up(Mat &image, vector<Mat> &pyramid_images, int level);
void pyramid_down(vector<Mat> &pyramid_images);

void laplaian_demo(vector<Mat> &pyramid_images, Mat &image);

void connected_component_demo(Mat &image);
void componentwithstats_demo(Mat &image);

void contours_info(Mat &image, vector<vector<Point>> &pts);
void contours_info(Mat &image, vector<vector<Point>> &pts, int threshold01, int threshold02);

void  open_demo(bool blnopen);
void  close_demo();

void sort_box(vector<Rect> &boxes);
Mat get_template(Mat &binary, vector<Rect> &rects);
void detect_defects(Mat &binary, vector<Rect> &rects, Mat &tpl, vector<Rect> &defects);

void process_frame(Mat &image);

vector<Point2f> featurePoints;
vector<Scalar> color_lut;
RNG rng;
void draw_lines(Mat &image, vector<Point2f> pt1, vector<Point2f> pt2);

void pause()
{
	printf("Press Enter key to continue...");
	fgetc(stdin);
}
int main()
{
	VideoCapture capture("../../images/bike.avi");
	if (!capture.isOpened()) {
		cout << "could not open video.." << endl;
		pause();
		return -1;
	}
	else
	{
		int fps = capture.get(CAP_PROP_FPS);
		int width = capture.get(CAP_PROP_FRAME_WIDTH);
		int height = capture.get(CAP_PROP_FRAME_HEIGHT);
		int num_of_frames = capture.get(CAP_PROP_FRAME_COUNT);
		printf("frame width: %d, frame height: %d, FPS : %d \n", width, height, fps);

		// 读取第一帧
		Mat preFrame, preGray;
		capture.read(preFrame);
		cvtColor(preFrame, preGray, COLOR_BGR2GRAY);//轉灰階
		GaussianBlur(preGray, preGray, Size(0, 0), 15);//高斯模糊

		Mat diff;
		Mat frame, gray;

		// 定义结构元素
		Mat k = getStructuringElement(MORPH_RECT, Size(7, 7));

		while (true)
		{
			bool ret = capture.read(frame);
			if (!ret) break;
			cvtColor(frame, gray, COLOR_BGR2GRAY);
			GaussianBlur(gray, gray, Size(0, 0), 15);

			subtract(gray, preGray, diff);//diff1 = prev2 – prev1
			threshold(diff, diff, 0, 255, THRESH_BINARY | THRESH_OTSU);

			morphologyEx(diff, diff, MORPH_OPEN, k);//開操作(morphologyEx)去除白色雜訊 強化/獲取 連通元件(mask)
			imshow("input", frame);
			imshow("result", diff);

			gray.copyTo(preGray);
			char c = waitKey(5);
			if (c == 27) {
				break;
			}
		}

		waitKey(0);
	}
	return 0;
}

void draw_lines(Mat &image, vector<Point2f> pt1, vector<Point2f> pt2) {
	if (color_lut.size() < pt1.size()) {
		for (size_t i = 0; i < pt1.size(); ++i) {
			int b = rng.uniform(0, 255);
			int g = rng.uniform(0, 255);
			int r = rng.uniform(0, 255);
			Scalar color(b, g, r);
			color_lut.push_back(color);
		}
	}

	for (size_t j = 0; j < pt1.size(); ++j) {
		line(image, pt1[j], pt2[j], color_lut[j], 2);
	}
}
void process_frame(Mat &image) {
	// Detector parameters
	int maxCorners = 100;
	double quality_level = 0.01;
	double minDistance = 0.04;

	// detecting corners
	Mat gray, dst;
	cvtColor(image, gray, COLOR_BGR2GRAY);
	vector<Point2f> corners;
	/*
	void cv::goodFeaturesToTrack(
	InputArray image,
	OutputArray corners,
	int maxCorners,
	double qualityLevel,
	double minDistance,
	InputArray mask = noArray(),
	int blockSize = 3,
	bool useHarrisDetector = false,
	double k = 0.04
	)
	src單通道輸入圖像，八位或者浮點數
	corners是輸出的關鍵點坐標集合
	maxCorners表示最大返回關鍵點數目
	qualityLevel表示拒絕的關鍵點 R < qualityLevel × max response將會被直接丟棄
	minDistance 表示兩個關鍵點之間的最短距離
	mask 表示mask區域，如果有表明只對mask區域做計算
	blockSize 計算梯度與微分的窗口區域
	useHarrisDetector 表示是否使用harris角點檢測，默認是false 為shi-tomas
	k = 0.04默認值，當useHarrisDetector為ture時候起作用
	*/
	goodFeaturesToTrack(gray, corners, maxCorners, quality_level,
		minDistance, Mat(), 3, false);

	// detect sub-pixel 亚像素检测
	Size winSize = Size(5, 5);
	Size zeroZone = Size(-1, -1);
	TermCriteria criteria = TermCriteria(TermCriteria::EPS + TermCriteria::COUNT, 40, 0.001);

	/*
	void cv::cornerSubPix(
	InputArray image,
	InputOutputArray corners,
	Size winSize,
	Size zeroZone,
	TermCriteria criteria
	)
	image单通道输入图像，八位或者浮点数
	corners是输入输出的关键点坐标集合
	winSize表示插值计算时候窗口大小
	zeroZone表示搜索区域中间的dead region边长的一半，有时用于避免自相关矩阵的奇异性。如果值设为(-1,-1)则表示没有这个区域。
	criteria角点精准化迭代过程的终止条件
	*/
	cornerSubPix(gray, corners, winSize, zeroZone, criteria);

	// drawing corner
	RNG rng;
	for (int i = 0; i < corners.size(); ++i) {
		int b = rng.uniform(0, 255);
		int g = rng.uniform(0, 255);
		int r = rng.uniform(0, 255);
		circle(image, corners[i], 5, Scalar(b, g, r), 3);
	}
}

void detect_defects(Mat &binary, vector<Rect> &rects, Mat &tpl, vector<Rect> &defects) {
	int height = tpl.rows;
	int width = tpl.cols;
	int index = 1;
	int size = rects.size();
	// 发现缺失
	for (int i = 0; i < size; ++i) {
		Mat roi = binary(rects[i]);
		resize(roi, roi, tpl.size());//調整待測物的大小與模板一致
		Mat mask;
		subtract(tpl, roi, mask);//圖像相減
		Mat se = getStructuringElement(MORPH_RECT, Size(5, 5));
		morphologyEx(mask, mask, MORPH_OPEN, se);//開運算-藉此去白色雜訊
		threshold(mask, mask, 0, 255, THRESH_BINARY);
		int count = 0;
		for (int row = 0; row < height; ++row) {
			for (int col = 0; col < width; ++col) {
				int pv = mask.at<uchar>(row, col);
				if (pv == 255) {
					++count;
				}
			}
		}
		if (count > 0) {
			defects.push_back(rects[i]);
		}
	}
}

Mat get_template(Mat &binary, vector<Rect> &rects) //以範圍最大為良品基準
{
	return binary(rects[0]);
}

void sort_box(vector<Rect> &boxes) {
	int size = boxes.size();
	for (int i = 0; i < size - 1; ++i) {
		for (int j = i; j < size; ++j) {
			if (boxes[j].y < boxes[i].y) {
				Rect tmp = boxes[i];
				boxes[i] = boxes[j];
				boxes[j] = tmp;
			}
		}
	}
}

void close_demo()
{
	//讀取圖像     
	Mat src = imread("../images/morph3.png");
	imshow("close_demo_input", src);

	//二值圖像
	Mat gray, binary;
	cvtColor(src, gray, COLOR_BGR2GRAY);
	threshold(gray, binary, 0, 255, THRESH_BINARY | THRESH_OTSU);
	imshow("close_demo_binary", binary);

	//閉操作//
	//Mat se = getStructuringElement(MORPH_ELLIPSE, Size(30, 30), Point(-1, -1));
	//Mat se = getStructuringElement(MORPH_RECT, Size(30, 30), Point(-1 , -1));
	Mat se = getStructuringElement(MORPH_RECT, Size(35, 35), Point(-1, -1));
	morphologyEx(binary, binary, MORPH_CLOSE, se);
	imshow("close_demo rect=35,35 ", binary);
}

void open_demo(bool blnopen)
{
	//讀取圖像     
	Mat src = imread("../images/fill.png");
	imshow("open_demo_input", src);

	//二值圖像
	Mat gray, binary;
	cvtColor(src, gray, COLOR_BGR2GRAY);
	if (blnopen)
	{
		threshold(gray, binary, 0, 255, THRESH_BINARY_INV | THRESH_OTSU);
	}
	else
	{
		threshold(gray, binary, 0, 255, THRESH_BINARY | THRESH_OTSU);
	}
	imshow("open_demo_binary", binary);

	//開操作 -去除黑色雜訊 強化/獲取 連通元件(mask) 保留長（x＝25）底線（y＝1）
	Mat se = getStructuringElement(MORPH_RECT, Size(25, 1), Point(-1, -1));
	if (blnopen)
	{
		morphologyEx(binary, binary, MORPH_OPEN, se);
	}
	else
	{
		morphologyEx(binary, binary, MORPH_CLOSE, se);//
		threshold(binary, binary, 0, 255, THRESH_BINARY_INV | THRESH_OTSU);
	}
	imshow("open_op", binary);

	//繪製填空位置
	vector < vector <Point>> contours;
	vector <Vec4i> hierarhy;
	findContours(binary, contours, hierarhy, RETR_EXTERNAL, CHAIN_APPROX_SIMPLE, Point(-1, -1));
	for (size_t t = 0; t < contours.size(); t++)
	{
		Rect roi = boundingRect(contours[t]);
		roi.y = roi.y - 10;
		roi.height = 12;
		rectangle(src, roi, Scalar(0, 0, 255));
	}

	//顯示結果
	imshow("open_demo", src);
}
void contours_info(Mat &image, vector<vector<Point>> &pts)//目標物為同類型(顏色) ~ 抓取輪廓(findContours)函數
{
	// 去噪声与二值化
	//彩色轉二值化步驟(SOP) 彩色 -> 高斯模糊(去雜訊) -> 轉灰階 -> 二值化
	Mat dst, gray, binary00;
	GaussianBlur(image, dst, Size(3, 3), 0, 0);
	cvtColor(dst, gray, COLOR_BGR2GRAY);
	threshold(gray, binary00, 0, 255, THRESH_BINARY | THRESH_OTSU);
	imshow("binary00", binary00);

	vector<Vec4i> hierarchy00;
	Scalar color = Scalar(255, 0, 0);
	/*
	void findContours(InputOutputArray image,OutputArrayOfArrays contours,OutputArray hierarchy,int mode,int method,Point offset = Point() )
	各個參數詳解如下：
	image表示輸入圖像，必須是二值圖像，二值圖像可以threshold輸出、Canny輸出、inRange輸出、自適應閾值輸出等。
	contours獲取的輪廓，每個輪廓是一系列的點集合
	hierarchy輪廓的層次信息，每個輪廓有四個相關信息，分別是同層下一個、前一個、第一個子節點、父節點
	mode 表示輪廓尋找時候的拓撲結搆返回
	-RETR_EXTERNAL表示只返回最外層輪廓
	-RETR_TREE表示返回輪廓樹結搆
	method表示輪廓點集合取得是基於什么算法，常見的是基於CHAIN_APPROX_SIMPLE鏈式編碼方法
	*/
	findContours(binary00, pts, hierarchy00, RETR_TREE, CHAIN_APPROX_SIMPLE, Point());

}
void contours_info(Mat &image, vector<vector<Point>> &pts, int threshold01, int threshold02)//目標物非同類型(顏色) ~ 抓取輪廓(findContours)函數
{
	Mat dst, gray, binary01;
	//彩色轉二值化步驟(直接使用Canny)
	/*
	void Canny(InputArray image, OutputArray edges, double threshold1, double threshold2, int apertureSize=3, bool L2gradient=false )
	image, edges：輸入和輸出的圖片。
	threshold1, threshold2：用來區分 strong edge 和 weak edge，範圍都是 0 ~ 255，會在實作過程中進一步討論，通常選擇 threshold2 / threshold1 = 1/2 ~ 1/3，例如 (70, 140), (70, 210)
	apertureSize：用來計算梯度的 kernel size，也就是 Sobel 的 ksize
	L2gradient：選擇要用 L1 norm（絕對值平均）還是 L2 norm（平方根）當作梯度的大小。預設是用 L1 norm
	*/
	Canny(image, binary01, threshold01, threshold02);

	// 膨胀
	/*
	OpenCV提供getStructuringElement()讓我們得到要進行侵蝕或膨脹的模板
	Mat getStructuringElement(int shape, Size ksize, Point anchor=Point(-1,-1))
	shape：模板形狀，有MORPH_RECT、MORPH_ELLIPSE、MORPH_CROSS三種可選。
	ksize：模板尺寸。
	*/
	Mat k = getStructuringElement(MORPH_RECT, Size(3, 3), Point(-1, -1));
	/*
	OpenCV膨脹
	dilate(const Mat &src, Mat &dst, Mat kernel, Point anchor=Point(-1,-1), int iterations=1)
	src：輸入圖，可以多通道，深度可為CV_8U、CV_16U、CV_16S、CV_32F或CV_64F。
	dst：輸出圖，和輸入圖尺寸、型態相同。
	kernel：結構元素，如果kernel=Mat()則為預設的3×3矩形，越大膨脹效果越明顯。
	anchor：原點位置，預設為結構元素的中央。
	iterations：執行次數，預設為1次，執行越多次膨脹效果越明顯。
	*/
	dilate(binary01, binary01, k);
	imshow("binary01", binary01);

	vector<Vec4i> hierarchy01;
	Scalar color = Scalar(255, 0, 0);
	findContours(binary01, pts, hierarchy01, RETR_EXTERNAL, CHAIN_APPROX_SIMPLE, Point());
}

void componentwithstats_demo(Mat &image)//八方鍊碼:元件標記/尋找/計算(計數)/參數:中心位置、起始座標、長、寬、面積，取得分類的所需資訊作業 + 繪製各元件的外矩形
{
	// extract labels
	//彩色轉二值化步驟(SOP) 彩色 -> 高斯模糊(去雜訊) -> 轉灰階 -> 二值化
	Mat gray, binary;
	GaussianBlur(image, image, Size(3, 3), 0);
	cvtColor(image, gray, COLOR_BGR2GRAY);
	threshold(gray, binary, 0, 255, THRESH_BINARY | THRESH_OTSU);
	imshow("input_binary", binary);
	showHistogram(binary, "Histogram_input_binary");

	Mat labels = Mat::zeros(image.size(), CV_32S);
	Mat stats, centroids;
	int num_labels = connectedComponentsWithStats(binary, labels, stats, centroids, 8, 4);
	cout << "total labels : " << num_labels - 1 << endl;
	vector<Vec3b> colors(num_labels);

	// 背景颜色
	colors[0] = Vec3b(0, 0, 0);

	// 目标颜色
	RNG rng;
	for (int i = 1; i < num_labels; ++i) {
		colors[i] = Vec3b(rng.uniform(0, 256), rng.uniform(0, 256), rng.uniform(0, 256));
	}

	// 抽取统计信息
	Mat dst = image.clone();
	for (int i = 1; i < num_labels; ++i) {
		// 中心位置
		int cx = centroids.at<double>(i, 0);
		int cy = centroids.at<double>(i, 1);

		// 统计信息
		int x = stats.at<int>(i, CC_STAT_LEFT);
		int y = stats.at<int>(i, CC_STAT_TOP);
		int w = stats.at<int>(i, CC_STAT_WIDTH);
		int h = stats.at<int>(i, CC_STAT_HEIGHT);
		int area = stats.at<int>(i, CC_STAT_AREA);

		// 中心位置绘制
		circle(dst, Point(cx, cy), 2, Scalar(0, 255, 0), 2);

		// 外接矩形
		Rect rect(x, y, w, h);
		rectangle(dst, rect, colors[i]);
		putText(dst, format("num:%d", i), Point(x, y), FONT_HERSHEY_SIMPLEX,
			.5, Scalar(0, 0, 255), 1);
		printf("num : %d, rice area : %d\n", i, area);
	}

	imshow("result", dst);
}

void connected_component_demo(Mat &image) //八方鍊碼 元件 計數(計算) 數量 / 標色
{
	// extract labels
	Mat gray, binary;

	//彩色轉二值化步驟(SOP) 彩色 -> 高斯模糊(去雜訊) -> 轉灰階 -> 二值化
	GaussianBlur(image, image, Size(3, 3), 0);
	cvtColor(image, gray, COLOR_BGR2GRAY);
	threshold(gray, binary, 0, 255, THRESH_BINARY | THRESH_OTSU);
	imshow("input_binary", binary);
	showHistogram(binary, "Histogram_input_binary");

	//計算(計數) 元件(mask) 數量 和 所需元素顏色數量陣列
	/*
	参数介绍如下：
	image：也就是输入图像，必须是二值图，即8位单通道图像。（因此输入图像必须先进行二值化处理才能被这个函数接受）
	返回值：
	num_labels：所有连通域的数目
	labels：图像上每一像素的标记，用数字1、2、3…表示（不同的数字表示不同的连通域）
	*/
	Mat labels = Mat::zeros(image.size(), CV_32S);//背景也會被算一個區域
	int num_labels = connectedComponents(binary, labels, 8, CV_32S);//數量
	cout << "total labels : " << num_labels - 1 << endl;
	vector<Vec3b> colors(num_labels);

	// 背景颜色
	colors[0] = Vec3b(0, 0, 0);

	// 目标颜色
	RNG rng;
	for (int i = 1; i < num_labels; ++i) {
		colors[i] = Vec3b(rng.uniform(0, 256), rng.uniform(0, 256), rng.uniform(0, 256));
	}

	// 给结果着色
	Mat dst = Mat::zeros(image.size(), image.type());
	for (int row = 0; row < image.rows; ++row) {
		for (int col = 0; col < image.cols; ++col) {
			int label = labels.at<int>(row, col);
			if (label == 0) continue;
			dst.at<Vec3b>(row, col) = colors[label];
		}
	}

	imshow("result", dst);
}

void laplaian_demo(vector<Mat> &pyramid_images, Mat &image)//拉普拉斯金字塔
{
	for (int i = pyramid_images.size() - 1; i > -1; --i)
	{
		Mat dst;
		if (i - 1 < 0)
		{
			pyrUp(pyramid_images[i], dst, image.size());
			subtract(image, dst, dst);//圖像相減
			dst = dst + Scalar(127, 127, 127); //调亮度， 实际中不能这么用
			imshow(format("laplaian_layer_%d", i), dst);
		}
		else
		{
			pyrUp(pyramid_images[i], dst, pyramid_images[i - 1].size());
			subtract(pyramid_images[i - 1], dst, dst);//圖像相減
			dst = dst + Scalar(127, 127, 127); //調亮度， 实际中不能这么用
			imshow(format("laplaian_layer_%d", i), dst);
		}
	}
}

void pyramid_down(vector<Mat> &pyramid_images)//高斯金字塔01
{
	for (int i = pyramid_images.size() - 1; i > -1; --i) {
		Mat dst;
		/*
		pyrUp(tmp, dst, Size(tmp.cols * 2, tmp.rows * 2))
		tmp: 當前影象， 初始化為原影象 src 。
		dst : 目的影象(顯示影象，為輸入影象的兩倍)
		Size(tmp.cols * 2, tmp.rows * 2) : 目的影象大小， 既然我們是向上取樣， pyrUp 期待一個兩倍於輸入影象(tmp)的大小。
		*/
		pyrUp(pyramid_images[i], dst);
		imshow(format("pyramid_down_%d", i), dst);
	}
}

void pyramid_up(Mat &image, vector<Mat> &pyramid_images, int level)//高斯金字塔02
{
	Mat temp = image.clone();
	Mat dst;
	for (int i = 0; i < level; ++i)
	{
		/*
		pyrDown( tmp, dst, Size( tmp.cols/2, tmp.rows/2 ))
		tmp: 當前影象， 初始化為原影象 src 。
		dst: 目的影象( 顯示影象，為輸入影象的一半)
		Size( tmp.cols/2, tmp.rows/2 ) :目的影象大小， 既然我們是向下取樣， pyrDown 期待一個一半於輸入影象( tmp)的大小。
		注意輸入影象的大小(在兩個方向)必須是2的冥，否則，將會顯示錯誤。
		最後，將輸入影象 tmp 更新為當前顯示影象, 這樣後續操作將作用於更新後的影象。
		tmp = dst;
		*/
		pyrDown(temp, dst);
		imshow(format("pyramid_up_%d", i), dst);
		temp = dst.clone();
		pyramid_images.push_back(temp);
	}
}

void USMImage(Mat src, Mat &usm, float fltPar)//圖像銳化增强演算法(USM)
{
	Mat blur_img;
	/*
	USM銳化公式表示如下：
	（源圖像– w*高斯模糊）/（1-w）；其中w表示權重（0.1～0.9），默認為0.6
	OpenCV中的代碼實現步驟
	– 高斯模糊
	– 權重疊加
	– 輸出結果
	*/
	GaussianBlur(src, blur_img, Size(0, 0), 25);
	addWeighted(src, (1 + fltPar), blur_img, (fltPar*-1), 0, usm);//原圖 : 模糊圖片= 1.5 : -0.5 的比例進行混合
	imshow("usm", usm);
	showHistogram(usm, "Histogram_input_usm");
}

void blur_demo(Mat &image, Mat &sum)
{
	int w = image.cols;
	int h = image.rows;
	Mat result = Mat::zeros(image.size(), image.type());
	int x2 = 0, y2 = 0;
	int x1 = 0, y1 = 0;
	int ksize = 5;
	int radius = ksize / 2;
	int ch = image.channels();
	int cx = 0, cy = 0;
	for (int row = 0; row < h + radius; row++) {
		y2 = (row + 1)>h ? h : (row + 1);
		y1 = (row - ksize) < 0 ? 0 : (row - ksize);
		for (int col = 0; col < w + radius; col++) {
			x2 = (col + 1)>w ? w : (col + 1);
			x1 = (col - ksize) < 0 ? 0 : (col - ksize);
			cx = (col - radius) < 0 ? 0 : col - radius;
			cy = (row - radius) < 0 ? 0 : row - radius;
			int num = (x2 - x1)*(y2 - y1);
			for (int i = 0; i < ch; i++) {
				// 积分图查找和表，计算卷积
				int s = getblockSum(sum, x1, y1, x2, y2, i);
				result.at<Vec3b>(cy, cx)[i] = saturate_cast<uchar>(s / num);
			}
		}
	}
	imshow("blur_demo", result);
}

/**
* 3x3 sobel 垂直边缘检测演示
*/
void edge_demo(Mat &image, Mat &sum)
{
	int w = image.cols;
	int h = image.rows;
	Mat result = Mat::zeros(image.size(), CV_32SC3);
	int x2 = 0, y2 = 0;
	int x1 = 0, y1 = 0;
	int ksize = 3; // 算子大小，可以修改，越大边缘效应越明显
	int radius = ksize / 2;
	int ch = image.channels();
	int cx = 0, cy = 0;
	for (int row = 0; row < h + radius; row++) {
		y2 = (row + 1)>h ? h : (row + 1);
		y1 = (row - ksize) < 0 ? 0 : (row - ksize);
		for (int col = 0; col < w + radius; col++) {
			x2 = (col + 1)>w ? w : (col + 1);
			x1 = (col - ksize) < 0 ? 0 : (col - ksize);
			cx = (col - radius) < 0 ? 0 : col - radius;
			cy = (row - radius) < 0 ? 0 : row - radius;
			int num = (x2 - x1)*(y2 - y1);
			for (int i = 0; i < ch; i++) {
				// 积分图查找和表，计算卷积
				int s1 = getblockSum(sum, x1, y1, cx, y2, i);
				int s2 = getblockSum(sum, cx, y1, x2, y2, i);
				result.at<Vec3i>(cy, cx)[i] = saturate_cast<int>(s2 - s1);
			}
		}
	}
	Mat dst, gray;
	convertScaleAbs(result, dst);
	normalize(dst, dst, 0, 255, NORM_MINMAX);
	cvtColor(dst, gray, COLOR_BGR2GRAY);
	imshow("edge_demo", gray);
}

int getblockSum(Mat &sum, int x1, int y1, int x2, int y2, int i) {
	int tl = sum.at<Vec3i>(y1, x1)[i];
	int tr = sum.at<Vec3i>(y2, x1)[i];
	int bl = sum.at<Vec3i>(y1, x2)[i];
	int br = sum.at<Vec3i>(y2, x2)[i];
	int s = (br - bl - tr + tl);
	return s;
}

void add_gaussian_noise(Mat &image)//高斯雜訊
{
	Mat noise = Mat::zeros(image.size(), image.type());
	// 产生高斯噪声
	randn(noise, (15, 15, 15), (30, 30, 30));
	Mat dst;
	add(image, noise, dst);
	image = dst.clone();//dst.copyTo(image);//圖像複製
						//imshow("gaussian_noise", dst);
}

void add_salt_pepper_noise(Mat &image)//白雜訊
{
	// 随机数产生器
	RNG rng(12345);
	for (int i = 0; i < 1000; ++i) {
		int x = rng.uniform(0, image.rows);
		int y = rng.uniform(0, image.cols);
		if (i % 2 == 1) {
			image.at<Vec3b>(y, x) = Vec3b(255, 255, 255);
		}
		else {
			image.at<Vec3b>(y, x) = Vec3b(0, 0, 0);
		}
	}
	//imshow("saltp_epper", image);
}

void blur3x3(Mat &src, Mat *det)
{
	// 3x3 均值模糊，自定义版本实现
	for (int row = 1; row < src.rows - 1; row++) {
		for (int col = 1; col < src.cols - 1; col++) {
			Vec3b p1 = src.at<Vec3b>(row - 1, col - 1);
			Vec3b p2 = src.at<Vec3b>(row - 1, col);
			Vec3b p3 = src.at<Vec3b>(row - 1, col + 1);
			Vec3b p4 = src.at<Vec3b>(row, col - 1);
			Vec3b p5 = src.at<Vec3b>(row, col);
			Vec3b p6 = src.at<Vec3b>(row, col + 1);
			Vec3b p7 = src.at<Vec3b>(row + 1, col - 1);
			Vec3b p8 = src.at<Vec3b>(row + 1, col);
			Vec3b p9 = src.at<Vec3b>(row + 1, col + 1);

			int b = p1[0] + p2[0] + p3[0] + p4[0] + p5[0] + p6[0] + p7[0] + p8[0] + p9[0];
			int g = p1[1] + p2[1] + p3[1] + p4[1] + p5[1] + p6[1] + p7[1] + p8[1] + p9[1];
			int r = p1[2] + p2[2] + p3[2] + p4[2] + p5[2] + p6[2] + p7[2] + p8[2] + p9[2];

			det->at<Vec3b>(row, col)[0] = saturate_cast<uchar>(b / 9);
			det->at<Vec3b>(row, col)[1] = saturate_cast<uchar>(g / 9);
			det->at<Vec3b>(row, col)[2] = saturate_cast<uchar>(r / 9);
		}
	}
}

void backProjection_demo(Mat &image, Mat &model)//反向投影
{
	Mat image_hsv, model_hsv;
	cvtColor(image, image_hsv, COLOR_BGR2HSV);//彩色轉HSV
	cvtColor(model, model_hsv, COLOR_BGR2HSV);

	// 定义直方图参数与属性
	int h_bins = 32, s_bins = 32;
	int histSize[] = { h_bins, s_bins };//要切分的像素強度值範圍，預設為256。每個channel皆可指定一個範圍。例如，[32,32,32] 表示RGB三個channels皆切分為32區段
	float h_ranges[] = { 0, 180 }, s_ranges[] = { 0, 256 };
	const float* ranges[] = { h_ranges, s_ranges };
	int channels[] = { 0, 1 };

	Mat roiHist;//計算ROI的直方圖
	calcHist(&model_hsv, 1, channels, Mat(), roiHist, 2, histSize, ranges);
	normalize(roiHist, roiHist, 0, 255, NORM_MINMAX, -1, Mat());

	Mat roiproj, backproj;
	calcBackProject(&image_hsv, 1, channels, roiHist, roiproj, ranges);//使用反向投影 產生ROI(前景)的mask
	bitwise_not(roiproj, backproj);//產生背景的mask
	imshow("ROIProj", roiproj);
	imshow("BackProj", backproj);
}

void showHistogram(InputArray src, cv::String StrTitle)//直方圖
{
	bool blnGray = false;
	if (src.channels() == 1)
	{
		blnGray = true;
	}

	// 三通道/單通道 直方圖 紀錄陣列
	vector<Mat> bgr_plane;
	vector<Mat> gray_plane;

	// 定义参数变量
	const int channels[1] = { 0 };
	const int bins[1] = { 256 };
	float hranges[2] = { 0, 255 };
	const float *ranges[1] = { hranges };
	Mat b_hist, g_hist, r_hist, hist;
	// 计算三通道直方图
	/*
	void calcHist( const Mat* images, int nimages,const int* channels, InputArray mask,OutputArray hist, int dims, const int* histSize,const float** ranges, bool uniform=true, bool accumulate=false );
	1.輸入的圖像數組
	2.輸入數組的個數
	3.通道數
	4.掩碼
	5.直方圖
	6.直方圖維度
	7.直方圖每個維度的尺寸數組
	8.每一維數組的範圍
	9.直方圖是否是均勻
	10.配置階段不清零
	*/
	if (blnGray)
	{
		split(src, gray_plane);
		calcHist(&gray_plane[0], 1, 0, Mat(), hist, 1, bins, ranges);
	}
	else
	{
		split(src, bgr_plane);
		calcHist(&bgr_plane[0], 1, 0, Mat(), b_hist, 1, bins, ranges);
		calcHist(&bgr_plane[1], 1, 0, Mat(), g_hist, 1, bins, ranges);
		calcHist(&bgr_plane[2], 1, 0, Mat(), r_hist, 1, bins, ranges);
	}

	/*
	* 显示直方图
	*/
	int hist_w = 512;
	int hist_h = 400;
	int bin_w = cvRound((double)hist_w / bins[0]);
	Mat histImage = Mat::zeros(hist_h, hist_w, CV_8UC3);
	// 归一化直方图数据
	if (blnGray)
	{
		normalize(hist, hist, 0, histImage.rows, NORM_MINMAX, -1);
	}
	else
	{
		normalize(b_hist, b_hist, 0, histImage.rows, NORM_MINMAX, -1);
		normalize(g_hist, g_hist, 0, histImage.rows, NORM_MINMAX, -1);
		normalize(r_hist, r_hist, 0, histImage.rows, NORM_MINMAX, -1);
	}

	// 绘制直方图曲线
	for (int i = 1; i < bins[0]; ++i)
	{
		if (blnGray)
		{
			line(histImage, Point(bin_w * (i - 1), hist_h - cvRound(hist.at<float>(i - 1))),
				Point(bin_w * (i), hist_h - cvRound(hist.at<float>(i))), Scalar(255, 255, 255),
				2, 8, 0);
		}
		else
		{
			line(histImage, Point(bin_w * (i - 1), hist_h - cvRound(b_hist.at<float>(i - 1))),
				Point(bin_w * (i), hist_h - cvRound(b_hist.at<float>(i))), Scalar(255, 0, 0),
				2, 8, 0);
			line(histImage, Point(bin_w * (i - 1), hist_h - cvRound(g_hist.at<float>(i - 1))),
				Point(bin_w * (i), hist_h - cvRound(g_hist.at<float>(i))), Scalar(0, 255, 0),
				2, 8, 0);
			line(histImage, Point(bin_w * (i - 1), hist_h - cvRound(r_hist.at<float>(i - 1))),
				Point(bin_w * (i), hist_h - cvRound(r_hist.at<float>(i))), Scalar(0, 0, 255),
				2, 8, 0);
		}


	}
	imshow(StrTitle, histImage);
}

★Python

import numpy as np
import cv2 as cv

cap = cv.VideoCapture("D:/images/video/bike.avi")
ret, prevFrame = cap.read()
prevGray = cv.cvtColor(prevFrame, cv.COLOR_BGR2GRAY)
prevGray = cv.GaussianBlur(prevGray, (0, 0), 15)
k = cv.getStructuringElement(cv.MORPH_RECT, (7, 7))
while True:
    ret, frame = cap.read()
    if ret is False:
        break
    gray = cv.cvtColor(frame, cv.COLOR_BGR2GRAY)
    gray = cv.GaussianBlur(gray, (0, 0), 15)
    diff = cv.subtract(gray, prevGray)
    t, binary = cv.threshold(diff, 0, 255, cv.THRESH_BINARY | cv.THRESH_OTSU)
    binary = cv.morphologyEx(binary, cv.MORPH_OPEN, k)
    cv.imshow('input', frame)
    cv.imshow('result', binary)
    cv.imwrite("D:/result.png", binary)
    c = cv.waitKey(50)&0xff
    prevGray = np.copy(gray)
    if c == 27:
        break
cap.release()
cv.destroyAllWindows()

★結果圖:

★延伸說明/重點回顧: