《学习OpenCV》练习题第四章第八题ab

这道题是利用OpenCV例子程序里自带的人脸检测程序，做点图像的复制操作以及alpha融合。

说明：人脸检测的程序我参照了网上现有的例子程序，没有用我用的OpenCV版本（2.4.5）的facedetect.c，人脸检测部分是一个月前写的程序，这次做了点改动，以前的部分注释了起来。

代码：

 #include <opencv/cv.h>
 #include <opencv/highgui.h>
 #include <opencv_libs.h>

 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <assert.h>
 #include <math.h>
 #include <float.h>
 #include <limits.h>
 #include <time.h>
 #include <ctype.h>

 /*
  *《学习OpenCV》第四章第八题
  * 完成时间：3:43 10/5 星期六 2013
  * 作者：[e-mail]
  */    

 /* Result window title */
 #define  WND_RESULT   "result"

 static CvMemStorage* storage = ;
 static CvHaarClassifierCascade* cascade = ;

 void detect_and_draw( IplImage* image );

 const char* cascade_name =
     "haarcascade_frontalface_alt.xml"; 

 /* Skull image */
 IplImage* g_skullImage;

 /* Trackbar initial value */
 int g_trackbar_value = ;
 /* Tackbar total values */
 int g_trackbar_total = ;

 /* Alpha blend's alpha */
 double g_alpha = ;

 /* Trackbar callback function */
 void switch_callback(int pos)
 {
     printf("Trackbar event.  pos: %d\n", pos);
     g_alpha = (double)pos / g_trackbar_total;
 }

 int main( )
 {
     CvCapture* capture = cvCreateCameraCapture();
     if(!capture)
     {
         printf("Camera error.\n");
         return -;
     }
     cascade_name = "haarcascade_frontalface_alt2.xml";
     cascade = (CvHaarClassifierCascade*)cvLoad( cascade_name, , ,  ); 

     if( !cascade )
     {
         printf( "ERROR: Could not load classifier cascade\n" );
         return -;
     } 

     storage = cvCreateMemStorage();
     cvNamedWindow( WND_RESULT,  ); 

     IplImage* frame = cvQueryFrame(capture);
     if(!frame)
     {
         return -;
     }

     // Load skull image
     IplImage* skullImage = cvLoadImage("skull.jpg", CV_LOAD_IMAGE_UNCHANGED);
     if(!skullImage)
     {
         printf("ERROR: Can't load skull image.\n");
         return -;
     }
     g_skullImage = cvCreateImage(cvGetSize(skullImage), skullImage->depth, );
     if(skullImage->nChannels != )
     {
         cvCvtColor(skullImage, g_skullImage, CV_GRAY2BGR);
     }
     else
     {
         cvCopy(skullImage, g_skullImage);
     }

     // Create trackbar
     cvCreateTrackbar("Switch", WND_RESULT, &g_trackbar_value,
         g_trackbar_total, switch_callback );
     // Initialize Alpha-Blend's alpha
     g_alpha = (double)g_trackbar_value / g_trackbar_total;

     char c;
     while(  )
     {
         frame = cvQueryFrame(capture);
         if(!frame)
         {
             return -;
         }

         detect_and_draw( frame ); 

         c = cvWaitKey();
         if(c == )
         {
             break;
         }
     }

     cvDestroyWindow(WND_RESULT);
     cvReleaseImage(&frame);
     cvReleaseCapture(&capture);
     cvReleaseImage(&skullImage);
     cvReleaseImage(&g_skullImage);

     return ;
 }

 void detect_and_draw(IplImage* img )
 {
     double scale=1.2;
     static CvScalar colors[] = {
         {{,,}},{{,,}},{{,,}},{{,,}},
         {{,,}},{{,,}},{{,,}},{{,,}}
     };//Just some pretty colors to draw with

     //Image Preparation
     //
     IplImage* gray = cvCreateImage(cvSize(img->width,img->height),,);
     IplImage* small_img=cvCreateImage(cvSize(cvRound(img->width/scale),cvRound(img->height/scale)),,);
     cvCvtColor(img,gray, CV_BGR2GRAY);
     cvResize(gray, small_img, CV_INTER_LINEAR);

     cvEqualizeHist(small_img,small_img); //直方图均衡

     //Detect objects if any
     //
     cvClearMemStorage(storage);
     double t = (double)cvGetTickCount();
     CvSeq* objects = cvHaarDetectObjects(small_img,
         cascade,
         storage,
         1.1,
         ,
         /*CV_HAAR_DO_CANNY_PRUNING*/,
         cvSize(,));

     t = (double)cvGetTickCount() - t;
     printf( "detection time = %gms\n", t/((double)cvGetTickFrequency()*.) );

     //Loop through found objects and draw boxes around them
     for(int i=;i<(objects? objects->total:);++i)
     {
         CvRect* r=(CvRect*)cvGetSeqElem(objects,i); 

         CvRect r_scale = cvRect( r->x * scale, r->y * scale, r->width * scale, r->height * scale );
         // 改变骷髅头图像大小
         IplImage * skullResize = cvCreateImage( cvSize(r_scale.width, r_scale.height),
             g_skullImage->depth, g_skullImage->nChannels );
         cvResize(g_skullImage, skullResize, CV_INTER_LINEAR);

         // 将人脸检测区域用骷髅头图像代替
         cvSetImageROI(img, r_scale);
         // b -- Alpha blend
         printf("Alpha: %f\t", g_alpha);
         cvAddWeighted( img, g_alpha, skullResize, 1.0 - g_alpha, 0.0, img);
        /* This is a part
         cvCopy(skullResize, img); */
         cvResetImageROI(img);
         cvReleaseImage(&skullResize);

      //   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( WND_RESULT, img );
     cvReleaseImage(&gray);
     cvReleaseImage(&small_img);
 }

运行结果（此时的alpha为0.2）：