如何在OpenCV 2.4.3中保存(cvWrite或imwrite)图像？

Question

我试图将OpenCV图像保存到硬盘驱动器.

这是我尝试过的:

public void SaveImage (Mat mat) {
  Mat mIntermediateMat = new Mat();

  Imgproc.cvtColor(mRgba, mIntermediateMat, Imgproc.COLOR_RGBA2BGR, 3);

  File path =
    Environment.getExternalStoragePublicDirectory(
    Environment.DIRECTORY_PICTURES);
  String filename = "barry.png";
  File file = new File(path, filename);

  Boolean bool = null;
  filename = file.toString();
  bool = Highgui.imwrite(filename, mIntermediateMat);

  if (bool == true)
    Log.d(TAG, "SUCCESS writing image to external storage");
    else
    Log.d(TAG, "Fail writing image to external storage");
  }
}

任何人都可以展示如何使用OpenCV 2.4.3保存该图像吗？

Answer 1

您的问题有点令人困惑,因为您的问题是关于桌面上的OpenCV,但您的代码是针对Android的,并且您询问IplImage,但您发布的代码是使用C++和Mat.假设您使用C++在桌面上,您可以执行以下操作:

cv::Mat image;
std::string image_path;
//load/generate your image and set your output file path/name
//...

//write your Mat to disk as an image
cv::imwrite(image_path, image);

......或者更完整的例子:

void SaveImage(cv::Mat mat)
{
    cv::Mat img;     
    cv::cvtColor(...); //not sure where the variables in your example come from
    std::string store_path("..."); //put your output path here       

    bool write_success = cv::imwrite(store_path, img);
    //do your logging... 
}

图像格式是根据提供的文件名选择的,例如,如果你的store_path字符串是"output_image.png",那么imwrite将保存它是一个PNG图像.您可以在OpenCV文档中查看有效扩展名列表.

使用OpenCV将图像写入磁盘时需要注意的一点是,缩放将根据Mat类型而有所不同; 也就是说,对于浮点数,图像应该在[0,1]范围内,而对于无符号字符,它们将来自[0,256].

对于IplImages,我建议只使用Mat,因为旧的C接口已被弃用.您可以将IplImage转换为Mat,cvarrToMat然后使用Mat,例如

IplImage* oldC0 = cvCreateImage(cvSize(320,240),16,1);
Mat newC = cvarrToMat(oldC0);
//now can use cv::imwrite with newC

或者,您可以将IplImage转换为Mat

Mat newC(oldC0); //where newC is a Mat and oldC0 is your IplImage

此外,我刚刚在OpenCV网站上注意到了这个教程,它为您提供了在(桌面)环境中加载和保存图像的步骤.