应用场景

画面遮蔽侦测主要应用于一些强制性开放的视频地点，如：煤矿矿产区，或者是一些特定的娱乐场所，这些视频在一些时候通常是要作为“现场证据”来呈现的，而有人的却可能由于各种原因，不想让视频给录下来…这个模块的目标就是检测出画面遮蔽，并告警通知相关人员去进行必要的处理。

工作原理

先将视频进行灰度处理，然后进行背景、前景差检测画面的差异，并检测差异部分是否是大片连续的，若是则认为画面被遮蔽。

补充说明

由于本算法对其应用场景有一定的特殊要求，若是放到不太合适的地方容易出现许多误报的状况。

以下是接口说明。

函式功能规格说明

全域类别说明

class CMaliciousDetect{

private:

bool bAlarmFlag;                                   //发出警告的bool variable

int nAlarmTimer;                             //警告时间

int nWidth, nHeight;                       //Frame之宽高

bool IsSetted;                                         //background是否设定变量

IplImage *Frame;                                   //input image

IplImage *Gray;                             //把input image转换成gray level

IplImage *C_edge;                       // The edge value image

IplImage *BG_edge;

IplImage *_small;                                //resize C_edge to _small

IplImage *BG_small;                            //       BG_edge to _small

CvHistogram *BG_hist,*C_hist;          //计算histogram for 变量BG_hist & C_hist

int hist_size ;                                         //设histogram之纵轴范围

CvScalar  num1 , num2 ;                     //计算BG_small&_small的edge value

int WCount;                                          //出现warning的时间变量

int OCount;                                     //发生状况一的遮蔽，计算秒数的变量

int ECount;                                     //发生状况二的遮蔽，计算秒数的变量

int HCount;                                     //发生状况三的遮蔽，计算秒数的变变

int H_HT ;                                       //histogram high and low threshold

int H_LT ;

double HistDiff;                                   //the difference of BG_hist & C_hist

public:

CMaliciousDetect( int nImageWidth, int nImageHeight, int nSeconds );  //建构子

~CMaliciousDetect();                                                                        //解构子

bool SetImage(BYTE *pImageArray);  //由AP承接image package

bool SetImage(IplImage *pImage);       //Whole algorithm

bool Alarm() {return bAlarmFlag;};      //send the alarm information

void ResetSystem() {IsSetted = false;};//判断是否已经设定background

};

成员函式说明:

CMaliciousDetect::CMaliciousDetect(int nImageWidth, int nImageHeight, int nSeconds){

Purpose：initial image variables and Hist variables.

Usage ：set all variable will use.

Parameter：

}

CMaliciousDetect::~CMaliciousDetect(){

Purpose：release variables

release all image variables

release both Hist variables

}

bool CMaliciousDetect::SetImage(BYTE* pImageArray){

Purpose: Succeed to AP’s package.

Usage: While webcam give image data into the program, check it data type.

Parameter:

Return:

True, if success

False, otherwise

}

bool CMaliciousDetect::SetImage(IplImage *pImage){

Purpose: detect whether the occlusion happened.

Usage: While AP given the right data type, starting the algorithm of detection

Parameter

Return:

True, if success

False, otherwise

}

测试程序及序列

测试程序: http://rg4.net/p/easyiv/libmaliciousdetect_test.7z

测试视频序列：http://rg4.net/p/easyiv/libmaliciousdetect_sample.7z