OCRHMMDecoder can't recognize text

[Pzixel]

• OpenCV => 3.4.0
• Operating System / Platform => Windows 10 64 Bit
• Compiler => mingw 7.2.0

I'm trying to adopt code from the webcam_demo

I also used OCRHMM_transitions_table.xml and OCRHMM_knn_model_data.xml.gz from webcam_demo. And here is adopted code:

std::string image_path = "assets/ubuntu.png";
std::string filename = "assets/OCRHMM_transitions_table.xml";
auto image_source = cv::imread(image_path);
cv::Mat image;
cv::cvtColor(image_source, image, 6);
cv::Mat transition_p;
cv::FileStorage fs(filename, cv::FileStorage::READ);
fs["transition_probabilities"] >> transition_p;
fs.release();
cv::Mat emission_p = cv::Mat::eye(62,62,CV_64FC1);
std::string voc = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
auto classifier = cv::text::loadOCRHMMClassifierNM("assets/OCRHMM_knn_model_data.xml.gz");
auto ocr = cv::text::OCRHMMDecoder::create(classifier, voc, transition_p, emission_p);

std::string output;
std::vector<cv::Rect> boxes;
std::vector<std::string> words;
std::vector<float> confidences;
ocr.get()->run(image, output, &boxes, &words, &confidences);
std::cout << output;

And it returns nothing but m for every image that I have. For example, this image:

Expected output: uBuntu

Actual output: m

It's either bug in implementation or invalid transition_p and emission_p in example, because OCRTesseract is working fine with same parameters and images.

[Pzixel]

Any progress on that?