cv::cvtColor fail

jniTest.cpp

// trying to convert Luv image to BGR

JNIEXPORT jboolean JNICALL Java_com_test_run(JNIEnv* env, jobject thiz, jlong data) {
  
  __android_log_write(ANDROID_LOG_INFO, "TEST", "run");
  if(data == 0) {
    __android_log_write(ANDROID_LOG_ERROR, "TEST", "empty jlong mat");
    return false;
  }
  
  cv::Mat frame = *((cv::Mat*)data);
  if(frame.empty()) {
    return false; 
  }
  
  cv::Mat bgr = cv::Mat(frame.rows, frame.cols);
  cv::cvtColor(frame, bgr, cv::COLOR_Luv2BGR);
  
  cv::Mat rotated;
  cv::Point2f center(frame.cols/2.0F, frame.rows/2.0F);
  cv::Mat rot = getRotationMatrix2D(center, 90, 1.0);
  cv::warpAffine(frame, rotated, rot, frame.size());
  
  return doCollStuff(rotated.data);
}

/* throws this error
 * 05-31 21:02:23.021 22356-22854/? E/cv::error(): OpenCV Error: Assertion failed (scn == 3 && (dcn == 3 || dcn == 4) && (depth == CV_8U || depth == CV_32F)) in void cv::cvtColor(cv::InputArray, cv::OutputArray, int, int), file /builds/master_pack-android/opencv/modules/imgproc/src/color.cpp, line 8291
 */

I guess your bgr Mat initialization is wrong. Try to create it like this: cv::Mat(frame.rows, frame.cols, CV_8UC3); Also, try to check images configurations using Mat::channels() and Mat::depth() methods.

@mshabunin thanks for your reply. Actually the image provided by android opencv wasn't Luv, was actually RGBA, I thought it was Luv since it looks "violet" when I saved it. I fixed changing cv::cvtColor(frame, bgr, CV_RGBA2BGR);