OpenCV Android crashes on Imgproc.cvtColor()

Question

I have a problem with OpenCV4Android.

java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.camtime/com.fognature.develop.smp.CameraActivity}: CvException [org.opencv.core.CvException: cv::Exception: /hdd2/buildbot/slaves/slave_ardbeg1/50-SDK/opencv/modules/imgproc/src/color.cpp:3739: error: (-215) scn == 3 || scn == 4 in function void cv::cvtColor(cv::InputArray, cv::OutputArray, int, int) ] at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2320) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2380) at android.app.ActivityThread.access$800(ActivityThread.java:151) at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1285) at android.os.Handler.dispatchMessage(Handler.java:102) at android.os.Looper.loop(Looper.java:135) at android.app.ActivityThread.main(ActivityThread.java:5289) at java.lang.reflect.Method.invoke(Native Method) at java.lang.reflect.Method.invoke(Method.java:372) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694) Caused by: CvException [org.opencv.core.CvException: cv::Exception: /hdd2/buildbot/slaves/slave_ardbeg1/50-SDK/opencv/modules/imgproc/src/color.cpp:3739: error: (-215) scn == 3 || scn == 4 in function void cv::cvtColor(cv::InputArray, cv::OutputArray, int, int) ] at org.opencv.imgproc.Imgproc.cvtColor_1(Native Method) at org.opencv.imgproc.Imgproc.cvtColor(Imgproc.java:4598) at com.fognature.develop.smp.CameraActivity.onCreate(CameraActivity.java:108) at android.app.Activity.performCreate(Activity.java:6018) at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1105) at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2273) ... 10 more

On this code part:

Mat sec;

@Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        sec = new Mat();
        setContentView(R.layout.activity_camera);
    File photo = new File(Environment.getExternalStorageState()


+File.separator+"SMP"+File.separator+getIntent().getStringExtra("c_name")+File.separator+getIntent().getStringExtra("last_photo"));
                sec = Highgui.imread(photo.getAbsolutePath());
                Imgproc.cvtColor(sec, sec, Imgproc.COLOR_RGBA2GRAY);
        }

It always crash on Imgproc.cvtColor(sec, sec, Imgproc.COLOR_RGBA2GRAY);

Answer 1

The error states that :

error: (-215) scn == 3 || scn == 4 in function void cv::cvtColor(cv::InputArray, cv::OutputArray, int, int) ]

which generally means that:

• When you are trying to convert RGBA2GRAY, then the input Mat sec in this case has Only 1 channel. You can confirm this by logging the sec.channels() just after reading it.
• It is also possible that, input Mat was empty or corrupted, to confirm you may check sec.width, sec.height, sec.depth, etc attributes to assure that it was loaded properly.