1. 程式人生 > >簡單的影象顯著性區域特徵提取方法-----opencv實現LC,AC,FT

簡單的影象顯著性區域特徵提取方法-----opencv實現LC,AC,FT

上文講了幾種簡單的方法,顯著性檢測就是把一幅影象中最吸引人注意的部分提取出來。 我用opencv重寫了LC,AC,FT三種演算法,程式碼和效果如下:
1.,後面的方法其實大概都是基於這個實現的,程式碼樣子差不多 LC思路就是利用對某個畫素點累加其與全幅畫素的距離(歐式距離),然後歸一化到0-255,由於是rgb資訊,於是用直方圖優化,提前計算好每個顏色與其他的距離和
void SalientRegionDetectionBasedonLC(Mat &src){
	int HistGram[256]={0};
	int row=src.rows,col=src.cols;
	int gray[row][col];
	//int Sal_org[row][col];
	int val;
	Mat Sal=Mat::zeros(src.size(),CV_8UC1 );
	Point3_<uchar>* p;
	for (int i=0;i<row;i++){
		for (int j=0;j<col;j++){
			p=src.ptr<Point3_<uchar> > (i,j);
			val=(p->x + (p->y) *2 + p->z)/4;
			HistGram[val]++;
			gray[i][j]=val;
		}
	}

	int Dist[256];
	int Y,X;
	int max_gray=0;
	int min_gray=1<<28;
	for (Y = 0; Y < 256; Y++)
    {
        val = 0;
        for (X = 0; X < 256; X++) 
            val += abs(Y - X) * HistGram[X];                //    論文公式(9),灰度的距離只有絕對值,這裡其實可以優化速度,但計算量不大,沒必要了
        Dist[Y] = val;
        max_gray=max(max_gray,val);
        min_gray=min(min_gray,val);
    }

    
    for (Y = 0; Y < row; Y++)
    {
        for (X = 0; X < col; X++)
        {
            Sal.at<uchar>(Y,X) = (Dist[gray[Y][X]] - min_gray)*255/(max_gray - min_gray);        //    計算全圖每個畫素的顯著性
        	//Sal.at<uchar>(Y,X) = (Dist[gray[Y][X]])*255/(max_gray);        //    計算全圖每個畫素的顯著性
        
        }
    }
    imshow("sal",Sal);
    waitKey(0);

}
效果圖
2.AC演算法也挺有意思,利用了類似影象金字塔演算法,在不同緯度(具體實現是用大小不同的均值濾波器過濾影象)與標準影象做差並累加,然後歸一化,實現如下:
void SalientRegionDetectionBasedonAC(Mat &src,int MinR2, int MaxR2,int Scale){
	Mat Lab;
	cvtColor(src, Lab, CV_BGR2Lab); 

	int row=src.rows,col=src.cols;
	int Sal_org[row][col];
	memset(Sal_org,0,sizeof(Sal_org));
	
	Mat Sal=Mat::zeros(src.size(),CV_8UC1 );

	Point3_<uchar>* p;
	Point3_<uchar>* p1;
	int val;
	Mat filter;

	int max_v=0;
	int min_v=1<<28;
	for (int k=0;k<Scale;k++){
		int len=(MaxR2 - MinR2) * k / (Scale - 1) + MinR2;
		blur(Lab, filter, Size(len,len ));
		for (int i=0;i<row;i++){
			for (int j=0;j<col;j++){
				p=Lab.ptr<Point3_<uchar> > (i,j);
				p1=filter.ptr<Point3_<uchar> > (i,j);
				//cout<<(p->x - p1->x)*(p->x - p1->x)+ (p->y - p1->y)*(p->y-p1->y) + (p->z - p1->z)*(p->z - p1->z) <<" ";
				
				val=sqrt( (p->x - p1->x)*(p->x - p1->x)+ (p->y - p1->y)*(p->y-p1->y) + (p->z - p1->z)*(p->z - p1->z) );
				Sal_org[i][j]+=val;
				if(k==Scale-1){
					max_v=max(max_v,Sal_org[i][j]);
					min_v=min(min_v,Sal_org[i][j]);
				}
			}
		}
	}
	
	cout<<max_v<<" "<<min_v<<endl;
	int X,Y;
    for (Y = 0; Y < row; Y++)
    {
        for (X = 0; X < col; X++)
        {
            Sal.at<uchar>(Y,X) = (Sal_org[Y][X] - min_v)*255/(max_v - min_v);        //    計算全圖每個畫素的顯著性
        	//Sal.at<uchar>(Y,X) = (Dist[gray[Y][X]])*255/(max_gray);        //    計算全圖每個畫素的顯著性
        }
    }
    imshow("sal",Sal);
    waitKey(0);
}

SalientRegionDetectionBasedonAC(test,test.rows/8,test.rows/2,3);

3.FT演算法 lab空間的均值減去當前畫素值
void SalientRegionDetectionBasedonFT(Mat &src){
	Mat Lab;
	cvtColor(src, Lab, CV_BGR2Lab); 

	int row=src.rows,col=src.cols;

	int Sal_org[row][col];
	memset(Sal_org,0,sizeof(Sal_org));
	
	Point3_<uchar>* p;

	int MeanL=0,Meana=0,Meanb=0;
	for (int i=0;i<row;i++){
		for (int j=0;j<col;j++){
			p=Lab.ptr<Point3_<uchar> > (i,j);
			MeanL+=p->x;
			Meana+=p->y;
			Meanb+=p->z;
		}
	}
	MeanL/=(row*col);
	Meana/=(row*col);
	Meanb/=(row*col);

	GaussianBlur(Lab,Lab,Size(3,3),0,0);

	Mat Sal=Mat::zeros(src.size(),CV_8UC1 );

	int val;

	int max_v=0;
	int min_v=1<<28;

	for (int i=0;i<row;i++){
		for (int j=0;j<col;j++){
			p=Lab.ptr<Point3_<uchar> > (i,j);
			val=sqrt( (MeanL - p->x)*(MeanL - p->x)+ (p->y - Meana)*(p->y-Meana) + (p->z - Meanb)*(p->z - Meanb) );
			Sal_org[i][j]=val;
			max_v=max(max_v,val);
			min_v=min(min_v,val);		
		}
	}
	
	cout<<max_v<<" "<<min_v<<endl;
	int X,Y;
    for (Y = 0; Y < row; Y++)
    {
        for (X = 0; X < col; X++)
        {
            Sal.at<uchar>(Y,X) = (Sal_org[Y][X] - min_v)*255/(max_v - min_v);        //    計算全圖每個畫素的顯著性
        	//Sal.at<uchar>(Y,X) = (Dist[gray[Y][X]])*255/(max_gray);        //    計算全圖每個畫素的顯著性
        }
    }
    imshow("sal",Sal);
    waitKey(0);
}