翻转图像以获得镜面效果

Question

我正在开发一个视频处理项目，需要一些帧翻转。我尝试使用 cvFlip 但似乎没有沿 y 轴翻转（x 轴工作...）并导致分段错误。还有其他选择吗？？

cv::Mat dst=src;      //src= source image from cam
cv::flip(dst, dst, 1);     //segmentation fault shown

imshow("flipped",dst);

Answer 1

cv::Mat src=imload("bla.png");
cv::Mat dst;               // dst must be a different Mat
cv::flip(src, dst, 1);     // because you can't flip in-place (leads to segfault)

Answer 2

使用

cv::flip

并将

1

传递为

flipcode

。

用示例代码查看你的编辑，你无法原地翻转。您需要一个单独的目的地

cv::Mat

:

cv::Mat dst;
cv::flip(src, dst, 1);
imshow("flipped",dst);

Answer 3

关键是创建与

dst

完全相同的

src

：

cv::Mat dst = cv::Mat(src.rows, src.cols, CV_8UC3);
cv::flip(src, dst, 1);

imshow("flipped", dst);

Answer 4

至少在openCV 4.8中，可以原地翻转。

可能的示例代码：

// buffer is a pointer to data, for example:
// uint8_t* buffer = new uint8_t[w*h*4]
// CV_8UC4 means unsigned byte, 4 channel image (for example RGBA)
// UMat allows to use GPU acceleration, it may be useful or not depending
// on the scenario, or you can simply just use cv::Mat.
cv::UMat m = cv::Mat(h , w, CV_8UC4, buffer).getUMat(cv::ACCESS_READ);
// flip accepts a flag that can be 0, <0 or >0
// here I put zero cause if the image is taken in landscape mode, although // looks like it needs vertical mirroring, it is actually horizontal. So you // may want to try the various options if 1 doesn't work as expected
flip(m, m, 0);