opencv 图像阴影检测

参数说明：

IplImage *workImg-当前全局变量,表示正在显示的图片。

downleft, upright- 检测出的阴影部分矩形框的两个对角顶点。

/*********************************************/
 //阴影检测
/*********************************************/

CvPoint downleft,upright;
int cnt;
int dir[8][2]={-1,-1,-1,0,-1,1,0,1,0,-1,1,1,1,0,1,-1};
#define SHADOW 170
#define Thres_KindNumber 20

bool InRange(CvPoint point,IplImage* pi) 
{
    int w=pi->width;
    int h=pi->height;
    if(point.x>=0&&point.x<w&&point.y>=0&&point.y<h)
    {
        float  v[3];
        for(i=0;i<3;i++)
        {
            v[i]=((uchar*)(pi->imageData + pi->widthStep*point.y))[point.x*3+i];
            if(v[i]<=SHADOW)
                return true;
        }
    }
    return false;
}

void Dye(IplImage** curimg,CvPoint s)
{
    int i;
    queue<CvPoint>Q;
    Q.push(s);

    for(i=0;i<3;i++)
        ((uchar*)((*curimg)->imageData + (*curimg)->widthStep*s.y))[s.x*3+i]=SHADOW+10;

    while(!Q.empty())
    {
        s=Q.front();
        Q.pop();

        if(s.x<downleft.x)    downleft.x=s.x;
        if(s.y<downleft.y)    downleft.y=s.y;
        if(s.x>upright.x)    upright.x=s.x;
        if(s.y>upright.y)    upright.y=s.y;

        //dye around
        for(i=0;i<8;i++)
        {
            CvPoint now=cvPoint(s.x+dir[i][0],s.y+dir[i][1]);
            if(InRange(now,*curimg))
            {
                Q.push(now);
                cnt++;
                for(i=0;i<3;i++)
                    ((uchar*)((*curimg)->imageData + (*curimg)->widthStep*now.y))[now.x*3+i]=SHADOW+10;
            }
        }
    }
}

void CCVMFCView::OnShadowDetect()
{
    //detect shadows,find the region with highest pixel value
    int x,y;
    srcimg=workImg;
    for(y=0;y<srcimg->height;y++)
        for(x=0;x<srcimg->width;x++)
        {
            CvPoint curp=cvPoint(x,y);
            downleft.x=srcimg->width;downleft.y=srcimg->height;
            upright.x=upright.y=0;
            cnt=0;

            if(InRange(curp,srcimg))
                Dye(&srcimg,curp);
            if(cnt>Thres_KindNumber)
                cvRectangle(workImg , downleft,upright,CV_RGB(0,255,0),1,CV_AA,0);
        }
        Invalidate();
}

from: http://blog.csdn.net/abcjennifer/article/details/7334043