在前两篇文章中,我介绍了《训练自己的haar-like特征分类器并识别物体》的前三个步骤:
1.准备训练样本图片,包括正例及反例样本
2.生成样本描述文件
3.训练样本
4.目标识别
==============
本文将着重说明最后一个阶段——目标识别,也即利用前面训练出来的分类器文件(.xml文件)对图片中的物体进行识别,并在图中框出在该物体。由于逻辑比较简单,这里直接上代码:
- int _tmain(int argc, _TCHAR* argv[])
- {
- char *cascade_name = CASCADE_HEAD_MY;
- cascade = (CvHaarClassifierCascade*)cvLoad( cascade_name, 0, 0, 0 );
-
- if( !cascade )
- {
- fprintf( stderr, "ERROR: Could not load classifier cascade\n" );
- system("pause");
- return -1;
- }
- storage = cvCreateMemStorage(0);
- cvNamedWindow( "face", 1 );
-
- const char* filename = "(12).bmp";
- IplImage* image = cvLoadImage( filename, 1 );
-
- if( image )
- {
- detect_and_draw( image );
- cvWaitKey(0);
- cvReleaseImage( &image );
- }
- cvDestroyWindow("result");
- return 0;
- }
实际检测的实现代码:
- void detect_and_draw(IplImage* img )
- {
- double scale=1.2;
- static CvScalar colors[] = {
- {{0,0,255}},{{0,128,255}},{{0,255,255}},{{0,255,0}},
- {{255,128,0}},{{255,255,0}},{{255,0,0}},{{255,0,255}}
- };
-
-
-
- IplImage* gray = cvCreateImage(cvSize(img->width,img->height),8,1);
- IplImage* small_img=cvCreateImage(cvSize(cvRound(img->width/scale)
- ,cvRound(img->height/scale)),8,1);
- cvCvtColor(img,gray, CV_BGR2GRAY);
- cvResize(gray, small_img, CV_INTER_LINEAR);
-
- cvEqualizeHist(small_img,small_img);
-
-
-
- cvClearMemStorage(storage);
- double t = (double)cvGetTickCount();
- CvSeq* objects = cvHaarDetectObjects(small_img,
- cascade,
- storage,
- 1.1,
- 2,
- 0,
- cvSize(30,30));
-
- t = (double)cvGetTickCount() - t;
- printf( "detection time = %gms\n", t/((double)cvGetTickFrequency()*1000.) );
-
-
- for(int i=0;i<(objects? objects->total:0);++i)
- {
- CvRect* r=(CvRect*)cvGetSeqElem(objects,i);
- cvRectangle(img, cvPoint(r->x*scale,r->y*scale)
- , cvPoint((r->x+r->width)*scale,(r->y+r->height)*scale), colors[i%8]);
- }
- for( int i = 0; i < (objects? objects->total : 0); i++ )
- {
- CvRect* r = (CvRect*)cvGetSeqElem( objects, i );
- CvPoint center;
- int radius;
- center.x = cvRound((r->x + r->width*0.5)*scale);
- center.y = cvRound((r->y + r->height*0.5)*scale);
- radius = cvRound((r->width + r->height)*0.25*scale);
- cvCircle( img, center, radius, colors[i%8], 3, 8, 0 );
- }
-
- cvShowImage( "result", img );
- cvReleaseImage(&gray);
- cvReleaseImage(&small_img);
- }
===================================
其实上面的代码可以运用于大部分模式识别问题,无论是自己生成的xml文件还是opencv自带的xml文件。在opencv的工程目录opencv\data文件夹下有大量的xml文件,这些都是opencv开源项目中的程序员们自己训练出来的。然而,效果一般不会合你预期,所以才有了本系列文章。天下没有免费的午餐,想要获得更高的查准率与查全率,不付出点努力是不行的!
(wengzilin) |