如何知道帧或图像的大小

How to know the size of a frame or image

本文关键字：图像 何知道      更新时间：2023-10-16

这对大多数人来说似乎微不足道，但我在确定视频帧的确切大小（即确切宽度和高度）时遇到了问题。我使用了cvGetSize，但我可能编码不准确，因为我遇到了一个错误。是否可以输出我的框架的宽度和高度值，因为我已经包含在下面的代码中？如果有人能就此向我提供建议，我将不胜感激。

#include "cv.h"
#include "highgui.h"
#include "iostream"
using namespace std;
int main( int argc, char* argv ) {
CvCapture *capture = NULL;
capture = cvCaptureFromAVI("C:\walking\lady walking.avi");
if(!capture){
    return -1;
}
IplImage* color_frame = NULL;
IplImage* gray_frame = NULL ;
int thresh_frame = 17;
int frameCount=0;//Counts every 5 frames
cvNamedWindow( "contours", CV_WINDOW_AUTOSIZE );
while(1) {
    color_frame = cvQueryFrame( capture );//Grabs the frame from a file
    if( !color_frame ) break;
    gray_frame = cvCreateImage(cvSize(color_frame->width, color_frame->height), color_frame->depth, 1);
    if( !color_frame ) break;// If the frame does not exist, quit the loop
    frameCount++;
    if(frameCount==5)
    {
        cvCvtColor(color_frame, gray_frame, CV_BGR2GRAY);
        cvThreshold(gray_frame, gray_frame, thresh_frame, 255, CV_THRESH_TOZERO_INV);
        cvGetSize(gray_frame);
        int w;
        int h;
        cvSize(w,h);
        cout <<" dimensions " <<  cvSize(w, h) << endl;
        cvShowImage("contours", gray_frame);
        frameCount=0;
    }
    char c = cvWaitKey(33);
    if( c == 27 ) break;
}
cvReleaseImage(&color_frame);
cvReleaseImage(&gray_frame);
cvReleaseCapture( &capture );
cvDestroyWindow( "contours" );
return 0;
}

尝试以下代码：）关键是cvGetSize函数和CvSize结构的使用。

#include "cv.h"
#include "highgui.h"
#include "iostream"
using namespace std;
int main( int argc, char* argv ) {
CvCapture *capture = NULL;
capture = cvCaptureFromAVI("C:\walking\lady walking.avi");
if(!capture){
    return -1;
}
IplImage* color_frame = NULL;
IplImage* gray_frame = NULL ;
int thresh_frame = 17;
int frameCount=0;//Counts every 5 frames
cvNamedWindow( "contours", CV_WINDOW_AUTOSIZE );
while(1) {
    color_frame = cvQueryFrame( capture );//Grabs the frame from a file
    if( !color_frame ) break;
    gray_frame = cvCreateImage(cvSize(color_frame->width, color_frame->height), color_frame->depth, 1);
    if( !color_frame ) break;// If the frame does not exist, quit the loop
    frameCount++;
    if(frameCount==5)
    {
        cvCvtColor(color_frame, gray_frame, CV_BGR2GRAY);
        cvThreshold(gray_frame, gray_frame, thresh_frame, 255, CV_THRESH_TOZERO_INV);
        CvSize dim = cvGetSize(gray_frame);
        cout <<" dimensions:: height:" <<  dim.height<<" width:"<< dim.width<< endl;
        cvShowImage("contours", gray_frame);
        frameCount=0;
    }
    char c = cvWaitKey(33);
    if( c == 27 ) break;
}
cvReleaseImage(&color_frame);
cvReleaseImage(&gray_frame);
cvReleaseCapture( &capture );
cvDestroyWindow( "contours" );
return 0;
}
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