Qt之图像处理（三）霍夫直线检测算法

霍夫直线检测算法

void MainWindow::Hough(QImage *origin,const int nLineRet, int (*pInfoRet)[3])
{


    QColor color;

    //pInfoRet[][0]代表Angle pInfoRet[][1]代表Dist pInfoRet[][2]代表Pixel数；
    //int pInfoRet [nLineRet][3];



    //极坐标域中最大的Rho和Theta
    int nMaxDist = sqrt((double)(origin->height()*origin->height()+origin->width()*origin->width()));
    int nMaxAngle = 90;


    //分配空间(累加器)
    int nAreaNum = nMaxAngle * nMaxDist * 2;
    int *pTransArea = new int[nAreaNum];
    memset(pTransArea,0,nAreaNum * sizeof(int));


    //转化到极坐标域
     BYTE bt;
     int nAngle;
     int nDist;
     double fRadian;
     for(int i = 0;i<origin->height();i++)
     {
         for(int j = 0;j<origin->width();j++)
         {

             color = QColor(origin->pixel(j, i));

             bt = color.red();
             if(bt>100)
             {
                 for(nAngle = 0; nAngle<nMaxAngle; nAngle++){
                     //弧长(0-PI)
                     fRadian = nAngle*PI*2 / 180.0;
                     //计算极径方程
                     nDist = (j*cos(fRadian) + i*sin(fRadian))+0.5;


                     if(nDist>=0)
                     {
                         pTransArea[nDist * nMaxAngle + nAngle]++;

                     }
                     else
                     {
                         nDist = fabs(nDist);

                         pTransArea[nMaxDist*nMaxAngle + nDist*nMaxAngle + nAngle]++;

                     }
                 }
             }
         }
     }


     //
     cout<<"pTransArea[0]"<<pTransArea[0]<<endl;
     cout<<"pTransArea[45]"<<pTransArea[45]<<endl;




    int Max_Angle = 0;
    int Max_Dist = 0;

    for(int nLine = 0; nLine < nLineRet; nLine++)
    {
        int Max_Value = 0;


        //寻找最大点

        for(int i = 0; i < nAreaNum; i++)
        {
            if(pTransArea[i]>Max_Value)
            {
                Max_Value = pTransArea[i];

                Max_Angle = i;

                cout<<"pTransArea[i]"<<Max_Value<<endl;
                cout<<"Max_Angle"<<Max_Angle<<endl;
            }
        }

        if(Max_Value == 0)
        {
            return ;
        }

        if(Max_Angle < nMaxAngle*nMaxDist)
        {
            // Max_Angle = nDist * nMaxAngle + nAngle



            Max_Dist = Max_Angle / nMaxAngle;
            Max_Angle = Max_Angle % nMaxAngle;


            cout<<"Max_Dist Max_Angle"<<Max_Angle<<endl;
            cout<<"Max_Dist"<<Max_Dist<<endl;


         }
        else {
            //Max_Angle = nMaxDist*nMaxAngle + nDist*nMaxAngle + nAngle

            Max_Angle -= nMaxAngle * nMaxDist;

            Max_Dist = Max_Angle / nMaxAngle;
            Max_Dist *= -1;

            Max_Angle = Max_Angle % nMaxAngle;
        }

        //将结果保存到pInfoRet
        cout<<"Max_Value"<<pInfoRet[nLine][1]<<endl;

        pInfoRet[nLine][0] = Max_Angle;
        pInfoRet[nLine][1] = Max_Dist;
        pInfoRet[nLine][2] = Max_Value;


        if(pInfoRet[nLine][1]<0)
        {
            pInfoRet[nLine][0] = pInfoRet[nLine][0] - 180;
            pInfoRet[nLine][1] = pInfoRet[nLine][1] * (-1);
        }






        int nMaxDisAll = 20;
        int nMaxAngleAll = 5;

        //将附近点清零。为寻找下一个峰值做准备

        for(nDist = (-1)*nMaxDisAll; nDist <= nMaxDisAll; nDist++ )
        {
            for(nAngle = (-1)*nMaxAngleAll; nAngle <= nMaxAngleAll; nAngle++)
            {
                int nThisDist = Max_Dist + nDist;
                int nThisAngle = Max_Angle + nAngle;


                nThisAngle *= 2;

                if(nThisAngle < 0 && nThisAngle >= -180)
                {

                    nThisAngle += 180;
                    nThisDist *= -1;
                }


                if(nThisAngle >= 180 && nThisAngle < 360)
                {
                    nThisAngle -= 180;
                    nThisDist *= -1;
                }


                if(fabs(nThisDist) <= nMaxDist && nThisAngle >= 0 && nThisAngle <= nMaxAngle*2)
                {

                    nThisAngle /= 2;
                    if(nThisDist >= 0)
                    {
                        pTransArea[nThisDist*nMaxAngle + nThisAngle] = 0;
                    }
                    else {
                        nThisDist = fabs(nThisDist);
                        pTransArea[nMaxDist*nMaxAngle + nThisDist*nMaxAngle + nThisAngle] = 0;
                    }
                }
            }
        }
    }

    delete []pTransArea;


}

调用：

 BYTE bt;
    for(int k = 0; k < 12; k++)
    {


        if(abs(pInfoRet[k][1])<30)
        {
            continue;
        }

        if(abs(pInfoRet[k][1])>500 && pInfoRet[k][0] == 0) continue;

        //cout<<"Dist"<<pInfoRet[k][1]<<"////"<<"Angle:"<<pInfoRet[k][0]<<endl;

        for(int i = 5; i<SobelIma.height()-5; i++)
        {
            for(int j = 5; j<SobelIma.width()-5; j++)
            {


                int nDist;
                oldColor = QColor(SobelIma.pixel(j,i));

                bt = oldColor.red();

                if(bt<10)
                {

                    continue;
                }

                nDist = (int) (j*cos(pInfoRet[k][0]*PI/180.0)+i*sin(pInfoRet[k][0]*PI/180.0)+0.5);

                if(nDist == pInfoRet[k][1])
                {


                    for(int h = -1 ; h<1;h++){

                        for(int w = -1;w<1;w++){

                             houghline.setPixel(j+w,i+h, qRgb(255, 255, 255));
                        }

                    }



                }
            }
        }
    }