opencv 学习之 车牌提取

车牌辨认分两步，1是车牌提取，而是字符辨认。

下面是车牌提取。

VS2010。

OpenCV249。

//载入图象 char * path = d:picture6.jpg; IplImage * frame = cvLoadImage(path); if(!frame) return 0; cvNamedWindow(frame,1); cvShowImage(frame,frame);

//均值滤波 cvSmooth(frame,frame,CV_MEDIAN); //cvSmooth(frame,CV_GAUSSIAN,3,3); //灰度图 IplImage * gray = cvCreateImage(cvGetSize(frame),frame->depth,1); cvCvtColor(frame,gray,CV_BGR2GRAY); cvNamedWindow(gray,1); cvShowImage(gray,gray);

//边沿检测 IplImage * temp = cvCreateImage(cvGetSize(gray),IPL_DEPTH_16S,1); //x方向梯度，垂直边沿 cvSobel(gray,temp,2,3); IplImage * sobel = cvCreateImage(cvGetSize(temp),IPL_DEPTH_8U,1); cvConvertScale(temp,sobel,1,0); cvNamedWindow(sobel,1); cvShowImage(sobel,sobel);

//2值化 IplImage * threshold = cvCreateImage(cvGetSize(sobel),gray->depth,1); cvThreshold(sobel,threshold,255,CV_THRESH_BINARY|CV_THRESH_OTSU); cvNamedWindow(threshold,1); cvShowImage(threshold,threshold);

//形态学变化 IplConvKernel * kernal; IplImage * morph = cvCreateImage(cvGetSize(threshold),threshold->depth,1); //自定义 1x3 的核进行 x 方向的膨胀腐蚀 kernal = cvCreateStructuringElementEx(3,CV_SHAPE_RECT); cvDilate(threshold,morph,kernal,2); //x 膨胀联通数字 cvErode(morph,4); //x 腐蚀去除碎片 cvDilate(morph,4); //x 膨胀回复形态 //自定义 3x1 的核进行 y 方向的膨胀腐蚀 kernal = cvCreateStructuringElementEx(1,CV_SHAPE_RECT); cvErode(morph,1); //y 腐蚀去除碎片 cvDilate(morph,3); //y 膨胀回复形态 cvNamedWindow(erode,1); cvShowImage(erode,morph);

//轮廓检测 IplImage * frame_draw = cvCreateImage(cvGetSize(frame),frame->nChannels); cvcopy(frame,frame_draw); CvMemStorage * storage = cvCreateMemStorage(0); CvSeq * contour = 0; int count = cvFindContours(morph,storage,&contour,sizeof(CvContour),CV_RETR_CCOMP,CV_CHAIN_APPROX_SIMPLE ); CvSeq * _contour = contour; for( ; contour != 0; contour = contour->h_next ) { double tmparea = fabs(cvContourArea(contour)); CvRect aRect = cvBoundingRect( contour,0 ); if(tmparea > ((frame->height*frame->width)/10)) { cvSeqRemove(contour,0); //删除面积小于设定值的轮廓,1/10 continue; } if (aRect.width < (aRect.height*2)) { cvSeqRemove(contour,0); //删除宽高比例小于设定值的轮廓 continue; } if ((aRect.width/aRect.height) > 4 ) { cvSeqRemove(contour,0); //删除宽高比例小于设定值的轮廓 continue; } if((aRect.height * aRect.width) < ((frame->height * frame->width)/100)) { cvSeqRemove(contour,0); //删除宽高比例小于设定值的轮廓 continue; } CvScalar color = CV_RGB( 255,0); cvDrawContours(frame_draw,contour,color,8 );//绘制外部和内部的轮廓 } cvNamedWindow(轮廓,1); cvShowImage(轮廓,frame_draw);

下面就是要字符分割与辨认了吧。