bgslibrary视频前景提取算法之三帧差法（二）

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BGSLibrary：A Background Subtraction Library
The BGSLibrary was developed by Andrews Sobral and provides an easy-to-use C++ framework based on OpenCV to perform background subtraction (BGS) in videos.
github介绍及下载地址 : https://github.com/andrewssobral/bgslibrary
现有30+种视频前景提取算法，不一定最优，但可以比较效果，准备研究其中部分。

三帧差法原理，参考opencv知识库
opencv-视频处理-实时前景检测–三帧差法
仅给出算法实现部分代码 ThreeFrameDiffBGS.cpp和ThreeFrameDiffBGS.h
IBGS.h 和main函数可以参考一篇

ThreeFrameDiffBGS.cpp

#include "ThreeFrameDiffBGS.h"

ThreeFrameDiffBGS::ThreeFrameDiffBGS() : firstTime(true), enableThreshold(true), threshold(15), showOutput(true)
{
    std::cout << "FrameDifferenceBGS()" << std::endl;
}

ThreeFrameDiffBGS::~ThreeFrameDiffBGS()
{
    std::cout << "~FrameDifferenceBGS()" << std::endl;
}

void ThreeFrameDiffBGS::process(const cv::Mat &img_input, cv::Mat &img_output, cv::Mat &img_bgmodel)
{
    if (img_input.empty())
        return;

    enableThreshold = true;
    threshold = 15;
    showOutput = true;

    if (img_input_prev2.empty())
    {
        img_input.copyTo(img_input_prev2);//前一帧为空时，将当前帧复制给前一帧
        return;
    }
    if (img_input_prev1.empty())
    {
        img_input.copyTo(img_input_prev1);//前一帧为空时，将当前帧复制给前一帧
        return;
    }
    //进行做差
    cv::absdiff(img_input_prev2, img_input_prev1, img_Differ1);
    cv::absdiff(img_input_prev1, img_input, img_Differ2);

    //先灰度化，然后用阈值提取前景背景
    if (img_Differ1.channels() == 3)
        cv::cvtColor(img_Differ1, img_Differ1, CV_BGR2GRAY);

    if (enableThreshold)
        cv::threshold(img_Differ1, img_Differ1, threshold, 255, cv::THRESH_BINARY);

    if (img_Differ2.channels() == 3)
        cv::cvtColor(img_Differ2, img_Differ2, CV_BGR2GRAY);

    if (enableThreshold)
        cv::threshold(img_Differ2, img_Differ2, threshold, 255, cv::THRESH_BINARY);

    //与运算
    cv::bitwise_and(img_Differ1, img_Differ2, img_foreground);

    //中值滤波
    //cv::medianBlur(img_foreground, img_foreground, 3);

    if (showOutput)
    {
        namedWindow("Frame Difference", cv::WINDOW_NORMAL);
        cv::imshow("Frame Difference", img_foreground);
    }

    img_foreground.copyTo(img_output);

    img_input_prev1.copyTo(img_input_prev2);
    img_input.copyTo(img_input_prev1);

    firstTime = false;
}

ThreeFrameDiffBGS .h

#pragma once

#include <iostream>
#include <opencv2/opencv.hpp>

#include "IBGS.h"

class ThreeFrameDiffBGS : public IBGS
{
private:
    bool firstTime;
    cv::Mat img_input_prev1;
    cv::Mat img_input_prev2;  //img_input_prev1的前一帧
    cv::Mat img_Differ1;      //differ1 = pre2 - pre1
    cv::Mat img_Differ2;      //differ2 = pre1 - precurrent
    cv::Mat img_foreground;
    bool enableThreshold;
    int threshold;
    bool showOutput;

public:
    ThreeFrameDiffBGS();
    ~ThreeFrameDiffBGS();

    void process(const cv::Mat &img_input, cv::Mat &img_output, cv::Mat &img_bgmodel);

//private:
//  void saveConfig();
//  void loadConfig();
};