java - OpenCV Android imwrite 给我一个蓝色图像

Question

我已经使用 CvCameraViewListener2 实现了一个摄像头，当我执行 imwrite 时，图片保存变成蓝色 这是我的代码

public Mat onCameraFrame(final CvCameraViewFrame inputFrame) {
    img_rgb = inputFrame.rgba();

    return img_rgb;

}

public void captureImage(View v){
    Mat mInter= new Mat(img_rgb.width(),img_rgb.height(),CvType.CV_32FC3);
    File path = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES);
    String filename = "temp.jpg";
    File file = new File(path, filename);
    Boolean bool = null;
    filename = file.toString();
    if(img_rgb.height() > img_rgb.width()){
        Core.flip(img_rgb,mInter,1);
        bool = Imgcodecs.imwrite(filename, mInter);
    }
    else{
    bool = Imgcodecs.imwrite(filename,mInter);}
    if (bool == true)
        Log.i(TAG, "SUCCESS writing image to external storage");
    else
        Log.i(TAG, "Fail writing image to external storage");
    String PathName = "";
    Intent i = new Intent(getApplication(),Result.class);
    i.putExtra(EXTRA_MESSAGE ,filename);
    startActivity(i); 

结果:

我找不到问题，我尝试将垫子转换成其他颜色但没有结果。

Answer 1

1. 根据翻转功能的文档:http://docs.opencv.org/java/2.4.2/org/opencv/core/Core.html#flip(org.opencv.core.Mat , org.opencv.core.Mat, 整数) mInter 应与 img_rgb 具有相同的类型，其类型为 CvType.CV_32FC4。 所以正确的初始化将是

   Mat mInter = new Mat(img_rgb.width(), img_rgb.height(), CvType.CV_32FC4);
   

2. 如果 if(img_rgb.height() > img_rgb.width()) 为假，mInter 包含空图像。所以你应该保存 img_rgb :

   else bool = Imgcodecs.imwrite(filename, img_rgb);
   

3. Imwrite 文档 http://docs.opencv.org/3.0-beta/modules/imgcodecs/doc/reading_and_writing_images.html :

Only 8-bit (or 16-bit unsigned (CV_16U) in case of PNG, JPEG 2000, and TIFF) single-channel or 3-channel (with ‘BGR’ channel order) images can be saved using this function. If the format, depth or channel order is different, use Mat::convertTo() , and cvtColor() to convert it before saving.

因此您需要使用 convert 将其从 rgba 转换为 bgr:

cv::cvtColor (input, input_bgr, CV_RGBA2BGR)

1. img_rgb 可以从不同的线程使用，所以应该添加同步。