OpenCV for Android: Simple example to convert Image to Greyscale -


as starter want convert bitmap greyscale via opencv. have running, crashes hard want convert image greyscale. can out? hope snippets enough, if not can attach rest.

part of java file:

                // convert opencv structure                 mat image = new mat();                 mat grayimage = new mat();                 utils.bitmaptomat(b2, image);                  // call opencv processing                 grayimage = converttogray (image);                  // convert                 utils.mattobitmap(grayimage, b2);

jni cpp file:

jniexport jlong jnicall java_com_my_sample_mainmenuactivity_converttogray (jnienv*, jobject, jlong addrrgba) {     logi("converting gray.");     mat *mrgba  = (mat*)addrrgba;      mat *_retval_;     cvtcolor(*mrgba, *_retval_, cv_rgb2gray);      logi("successfully finished converting gray.");     return (jlong) _retval_; }

it never gets logging successful having converted image. seems if bitmap not converted mat. bitmap exist, can show on imageview. clue i'm (obviously) doing wrong?

05-14 21:26:27.082: i/native(22394): converting gray. 05-14 21:26:27.082: a/libc(22394): fatal signal 11 (sigsegv) @ 0xcd10001d (code=1), thread 22394 (ialabs.mysample)

sorry if question answered elsewhere, haven't found example mat, iplimage, seems.

you have 2 empty mat objects. can't convert that's empty gray.

try this:

mat tmp = new mat (b.getwidth(), b.getheight(), cvtype.cv_8uc1); utils.bitmaptomat(b, tmp); imgproc.cvtcolor(tmp, tmp, imgproc.color_rgb2gray);

where b image bitmap.

utils.mattobitmap(tmp, b);

add convert mat object bitmap.


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