《学习OpenCV》第二章 课后题5

题目叙述：给程序加入滚动条，使得用户可以动态调节缩放比例，缩放比例的取值为2~8之间。可以跳过写入磁盘操作，但是必须将变换结果显示在窗口中。

#include "cv.h"#include "highgui.h"#include <stdio.h> int pos = 2 ;// Convert a video to grayscale// argv[1]: input video file// argv[2]: name of new output file////#define NOWRITE 1;   //Turn this on (removed the first comment out "//" if you can't write on linuxvoid ON_Change(int n)  {       //printf("d%",n);    pos = n;}  void main(  ) {    cvNamedWindow( "Example2_10", CV_WINDOW_AUTOSIZE );    cvNamedWindow( "Log_Polar", CV_WINDOW_AUTOSIZE );    CvCapture* capture = cvCreateFileCapture("G:/数据/OpenCV数据/song.mp4" );    //if (!capture){    //    return -1;    //}    cvCreateTrackbar("scale","Example2_10",&pos,8,ON_Change);//创建滚动条     IplImage* bgr_frame;    double fps = cvGetCaptureProperty (        capture,        CV_CAP_PROP_FPS    );    printf("fps=%d\n",(int)fps);    CvSize size = cvSize(        (int)cvGetCaptureProperty( capture, CV_CAP_PROP_FRAME_WIDTH),        (int)cvGetCaptureProperty( capture, CV_CAP_PROP_FRAME_HEIGHT)    );    printf("frame (w, h) = (%d, %d)\n",size.width,size.height);#ifndef NOWRITE CvVideoWriter* writer = cvCreateVideoWriter(          "G:/数据/OpenCV数据/wind-img2.avi",                                       CV_FOURCC('M','J','P','G'),            fps,        size    );#endif    IplImage* logpolar_frame = cvCreateImage(        size,        IPL_DEPTH_8U,        3    );    IplImage* gray_frame = cvCreateImage(        size,        IPL_DEPTH_8U,        1    );    while( (bgr_frame=cvQueryFrame(capture)) != NULL ) {        cvShowImage( "Example2_10", bgr_frame );       //We never make use of this gray image        cvConvertImage(               bgr_frame,            gray_frame,            CV_RGB2GRAY        );        //This is just a fun conversion the mimic's the human visual system        cvLogPolar( bgr_frame, logpolar_frame,                      cvPoint2D32f(bgr_frame->width/2,                    bgr_frame->height/2),                     40,                     CV_INTER_LINEAR+CV_WARP_FILL_OUTLIERS );        IplImage* img2 = cvCreateImage( cvSize( logpolar_frame->width/(pos+1),logpolar_frame->height/(pos+1)), logpolar_frame->depth, logpolar_frame->nChannels);        cvResize(logpolar_frame, img2, CV_INTER_LINEAR);         cvShowImage( "Log_Polar", img2 );        //Sigh, on linux, depending on your ffmpeg, this often won't work ...//#ifndef NOWRITE//       cvWriteToAVI( writer, img2 );//#endif        char c = cvWaitKey(10);        if( c == 27 ) break;    }#ifndef NOWRITE    cvReleaseVideoWriter( &writer );#endif    cvReleaseImage( &gray_frame );    cvReleaseImage( &logpolar_frame );    cvReleaseCapture( &capture );}

注：不要将滚动条放在缩放的窗口中，因为效果不好，喜欢的可以试试看！