将OpenCv Mat插入C++ std :: vector

Question

我正在将Mat对象推入std :: vector.

但是,当我在那之后尝试访问元素(Mat)时,它没有给我之前推送的图像,具体取决于frameOrientation.

例如,在下面的情况中,我得到"after_push_rotated2.jpg"与"before_push_rotated3.jpg"相同,这不应该是.

如果我将frameOrientation设置为所有"2s"或"4s",则"after_push_rotated1/2/3.jpg"都是相同的并且等于"before_push_rotated3.jpg".

这有什么不对？

#include <cv.h>
#include <cxcore.h>
#include <highgui.h>
#include <iostream>
#include <vector>

using namespace cv;
using namespace std;

vector<Mat> checkOrientationAndRotate()
{
    Mat frame1 = imread("1.jpg" );
    Mat frame2 = imread("2.jpg" );
    Mat frame3 = imread("3.jpg" );



    vector<Mat> frameList;
    vector<Mat> frameList_rotated;

    frameList.push_back(frame1);
    frameList.push_back(frame2);
    frameList.push_back(frame3);

    Mat transposedFrame;
    Mat rotatedFrame;

    int i=0;
    for (vector<Mat>::iterator iter = frameList.begin(); iter != frameList.end(); iter++)
    {
        //Check for orientation of that frame
        int frameOrientation;
        if (i==0) frameOrientation = 1;
        if (i==1) frameOrientation = 2;
        if (i==2) frameOrientation = 4;

        switch (frameOrientation)
        {
        case 1: //1 - no rotate
            rotatedFrame = *iter;
            break;

        case 2: //2 - rotate it ACW 90 deg
            transpose(*iter, transposedFrame);
            flip(transposedFrame, rotatedFrame, 0);
            break;

        case 3: //3 - rotate it 180deg
            flip(*iter, rotatedFrame, -1);
            break;

        case 4: //4 - rotate it CW 90 deg
            transpose(*iter, transposedFrame);
            flip(transposedFrame, rotatedFrame, 1);
            break;
        default:
            break;
        }

        //Check frame before pushing into vector
        if (i==0) imwrite("before_push_rotated1.jpg",rotatedFrame);
        if (i==1) imwrite("before_push_rotated2.jpg",rotatedFrame);
        if (i==2) imwrite("before_push_rotated3.jpg",rotatedFrame);

        frameList_rotated.push_back(rotatedFrame);


        //Check frame after pushing into vector.
        //Depending on the frameorientation, the frames are not the frames pushed in earlier!
        int n=0;
        for (vector<Mat>::iterator iter = frameList_rotated.begin(); iter != frameList_rotated.end(); iter++)
        {
            Mat frame = *iter;
            if (n==0) imwrite("after_push_rotated1.jpg",frame);
            if (n==1) imwrite("after_push_rotated2.jpg",frame);
            if (n==2) imwrite("after_push_rotated3.jpg",frame);
            n++;
        }

        i++;
        } //for

        return frameList_rotated;

}

void main()
{
    vector<Mat> frameList_rotated = checkOrientationAndRotate();
}

Answer 1

[我最近没有使用OpenCV,所以我可能错了,如果我是,请告诉我:)]

Mat表示(种类)图像标题,而不是图像数据.OpenCV在内部维护一个引用计数机制,以避免在不同区域复制大量图像像素数据.意思是说当你说:

Mat a = b; // Only headers are copied, both a and b refer to the same image.

在上述情况下,如果您修改b,更改也将反映a在内.在这种情况下你需要使用的是:

Mat a = b.clone();

关于你的情况,我真的认为以下行应该解决问题(如果没有,控制流可能还有其他一些问题,呵呵):

尝试更换:

Mat transposedFrame;
Mat rotatedFrame;

有:

 //create a new image, not just the headers..
Mat transposedFrame(Size(image_width, image_height), image.type());
Mat rotatedFrame(Size(image_width, image_height), image.type());