Question

我正在使用omr在android中制作opencv扫描程序，并且我已经获得了处理示例图像的图像处理代码。现在，当我将样本图像替换为来自相机的实际图像，同时将bitmap转换为Mat时，它会抛出nullpointer，就好像我显示该位图图像一样，它会正确地显示它。请帮我解决这个nullpointer异常。

我的图像存储在存储中，我正在通过意图中的附加功能将uri传递给当前活动。

我的图像处理活动和显示图像是

public class ImageDisplayActivity extends AppCompatActivity {

private static final String TAG = "ImageDisplayActivity";

private static ImageView imageView;
private String filename;
private Uri fileUri;
private Bitmap image;
private Mat localMat;

private BaseLoaderCallback mLoaderCallback = new BaseLoaderCallback(this) {
    @Override
    public void onManagerConnected(int status) {
        switch (status) {
            case LoaderCallbackInterface.SUCCESS:
            {
                Log.i(TAG, "OpenCV loaded successfully");
                localMat = new Mat();
            } break;
            default:
            {
                super.onManagerConnected(status);
            } break;
        }
    }
};

public ImageDisplayActivity() {
    Log.i(TAG, "Instantiated new " + this.getClass());
}

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_image_display);

    filename = getIntent().getStringExtra("filename");
    fileUri = Uri.parse(filename);
    //filename="/storage/sdcard/omr.jpg";
    //filename= Environment.getExternalStorageDirectory().getPath()+"download/BJq8M.jpg";
    imageView = (ImageView)findViewById(R.id.displayImage);
    BitmapFactory.Options options = new BitmapFactory.Options();

    // downsizing image as it throws OutOfMemory Exception for larger
    // images

    image=BitmapFactory.decodeFile(fileUri.getPath());
    Utils.bitmapToMat(image, localMat);
    //detectEdges(image);
    showAllCircles(image);

    //this line properly displays image preview
    //this.imageView.setImageBitmap(image);


}

Showcircle是

 public void showAllCircles(Bitmap paramView)
{

    Mat localMat1 = new Mat();
    //throws nullpointer exception here for localmat1
    Utils.bitmapToMat(paramView, localMat1);

    Mat localMat2 = new Mat();
    Imgproc.GaussianBlur(localMat1, localMat2, new Size(5.0D, 5.0D), 7.0D, 6.5D);
    Object localObject = new Mat();
    Imgproc.cvtColor(localMat2, (Mat)localObject, COLOR_RGB2GRAY);
    Mat cloneMat= ((Mat) localObject).clone();
    //Mat blackwhite= ((Mat) localObject).clone();
    localMat2 = localMat1.clone();
    bitwise_not(cloneMat,cloneMat);
    Imgproc.threshold(cloneMat,localMat2,127,255,Imgproc.THRESH_OTSU);
    Mat thresh=localMat2.clone();

    List<MatOfPoint> contours = new ArrayList<MatOfPoint>();
    List<MatOfPoint> questions = new ArrayList<MatOfPoint>();
    List<MatOfPoint> sorted = new ArrayList<MatOfPoint>();

    Mat hierarchy = new Mat();
    Imgproc.findContours(localMat2, contours, hierarchy, Imgproc.RETR_EXTERNAL, Imgproc.CHAIN_APPROX_SIMPLE);
    Rect rect,rect2;
    int groups[] = new int[30];
    int i=0,l=0;
    for (int contourIdx = 0; contourIdx < contours.size(); contourIdx++) {
         rect = Imgproc.boundingRect(contours.get(contourIdx));
        //float area=rect.width/(float)rect.height;


        if(rect.width>=29 && rect.height>=29){
            questions.add(contours.get(contourIdx));

            //rect3 = Imgproc.boundingRect(questions.get(i));
            //Log.i("Before------",rect3.tl()+" ");

           for(int ctr=0;ctr<questions.size()-1;ctr++){
                MatOfPoint ctr1 = questions.get(i);
                rect = Imgproc.boundingRect(questions.get(i));
                MatOfPoint ctr2 = questions.get(ctr);
                rect2 = Imgproc.boundingRect(questions.get(ctr));
                if(rect.tl().x<rect2.tl().x){
                        questions.set(ctr,ctr1);
                    questions.set(i,ctr2);
                }
            }
            //rect3 = Imgproc.boundingRect(questions.get(i));
            //Log.i("after",rect3.tl()+" ");
            i++;

            if(i%5==0){
                groups[l]=questions.indexOf(contours.get(contourIdx));
                l++;
                //Log.i("groups---",""+groups[l-1]);

            }
        }
    }

    int j=0;i=0;
    while(j!=questions.size()){

        for(int ctr=0;ctr<questions.size()-1;ctr++){
            MatOfPoint ctr1 = questions.get(i);
            rect = Imgproc.boundingRect(questions.get(i));
            MatOfPoint ctr2 = questions.get(ctr);
            rect2 = Imgproc.boundingRect(questions.get(ctr));
            if(rect.tl().y<rect2.tl().y){
                questions.set(ctr,ctr1);
                questions.set(i,ctr2);
            }
        }
    i++;
    j++;
    }

    //Collections.sort(questions, Collections.reverseOrder());
    int bubble =0;
    for (int contourIdx = 0; contourIdx < questions.size(); contourIdx++) {

        Rect rectCrop = boundingRect(questions.get(contourIdx));
        Mat imageROI= thresh.submat(rectCrop);

        int total = countNonZero(imageROI);
        double pixel =total/contourArea(questions.get(contourIdx))*100;
        if(pixel>=80){
            Log.i("Answer:",bubble+" - "+contourIdx%5);
            //sorted.add(questions.get(contourIdx));
            Imgproc.drawContours(localMat1, questions, contourIdx, new Scalar(255.0D, 0.0D, 0.0D), 2);
            bubble++;

        }

    }

    //Random rnd = new Random();
    //i=0;
    //int r=0,g=0,b=0;

    /*for (int contourIdx = 0; contourIdx <sorted.size(); contourIdx++) {

           // r=rnd.nextInt(256);
            //g=rnd.nextInt(256);
            //b=rnd.nextInt(256);
        Imgproc.drawContours(localMat1, sorted, contourIdx, new Scalar(255.0D, 0.0D, 0.0D), 2);
        i=i+1;
        //Log.i("Local Objects","Local Object Point -
        // ------------------"+localMat2);
    }*/

    // displays final image
    Utils.matToBitmap(localMat1, paramView);
    this.imageView.setImageBitmap(paramView);

}

Android控制台错误

E / AndroidRuntime：致命异常：主要处理：com.example.admin.app，PID：7310 java.lang.RuntimeException：无法启动活动ComponentInfo {com.example.admin.app/com.example.admin.app.ImageDisplayActivity}：java.lang.IllegalArgumentException：mat == null 在android.app.ActivityThread.performLaunchActivity（ActivityThread.java:2325）在android.app.ActivityThread.handleLaunchActivity（ActivityThread.java:2387）在android.app.ActivityThread.access $ 800（ActivityThread.java:151）在android.app.ActivityThread $ H.handleMessage（ActivityThread.java:1303）在android.os.Handler.dispatchMessage（Handler.java:102）在android.os.Looper.loop（Looper.java:135）在android.app.ActivityThread.main（ActivityThread.java:5254） at java.lang.reflect.Method.invoke（Native Method）在java.lang.reflect.Method.invoke（Method.java:372）在com.android.internal.os.ZygoteInit $ MethodAndArgsCaller.run（ZygoteInit.java:903）在com.android.internal.os.ZygoteInit.main（ZygoteInit.java:698）引起：java.lang.IllegalArgumentException：mat == null 在org.opencv.android.Utils.bitmapToMat（Utils.java:92）在org.opencv.android.Utils.bitmapToMat（Utils.java:102） at com.example.admin.bubbleboard.ImageDisplayActivity.onCreate（ImageDisplayActivity.java:94）在android.app.Activity.performCreate（Activity.java:5990）在android.app.Instrumentation.callActivityOnCreate（Instrumentation.java:1106）在android.app.ActivityThread.performLaunchActivity（ActivityThread.java:2278）在android.app.ActivityThread.handleLaunchActivity（ActivityThread.java:2387）在android.app.ActivityThread.access $ 800（ActivityThread.java:151）在android.app.ActivityThread $ H.handleMessage（ActivityThread.java:1303）在android.os.Handler.dispatchMessage（Handler.java:102）在android.os.Looper.loop（Looper.java:135）在android.app.ActivityThread.main（ActivityThread.java:5254） at java.lang.reflect.Method.invoke（Native Method）在java.lang.reflect.Method.invoke（Method.java:372）

Answer 1

我把这个问题排序了。这是因为我的opencv库是在onCreate方法之后加载的。

opencv android bitmap将结果映射为null

1 个答案: