Create cpp and build it using tesseract OCR and openCV in ubuntu

install openCV

sudo apt-get update
sudo apt-get install libopencv-dev
pkg-config --cflags --libs opencv4 # 설치 확인
  • output
-I/usr/include/opencv4/opencv -I/usr/include/opencv4 -lopencv_stitching -lopencv_aruco -lopencv_bgsegm -lopencv_bioinspired -lopencv_ccalib -lopencv_dnn_objdetect -lopencv_dnn_superres -lopencv_dpm -lopencv_highgui -lopencv_face -lopencv_freetype -lopencv_fuzzy -lopencv_hdf -lopencv_hfs -lopencv_img_hash -lopencv_line_descriptor -lopencv_quality -lopencv_reg -lopencv_rgbd -lopencv_saliency -lopencv_shape -lopencv_stereo -lopencv_structured_light -lopencv_phase_unwrapping -lopencv_superres -lopencv_optflow -lopencv_surface_matching -lopencv_tracking -lopencv_datasets -lopencv_text -lopencv_dnn -lopencv_plot -lopencv_ml -lopencv_videostab -lopencv_videoio -lopencv_viz -lopencv_ximgproc -lopencv_video -lopencv_xobjdetect -lopencv_objdetect -lopencv_calib3d -lopencv_imgcodecs -lopencv_features2d -lopencv_flann -lopencv_xphoto -lopencv_photo -lopencv_imgproc -lopencv_core
  • 환경변수 등록
export PKG_CONFIG_PATH=/usr/lib/x86_64-linux-gnu/pkgconfig:$PKG_CONFIG_PATH

install tesseract

  • 설치
sudo apt update
sudo add-apt-repository ppa:alex-p/tesseract-ocr-devel # 최신 개발 버전 5.3.4, 추론 정확도 높음.
# sudo add-apt-repository ppa:alex-p/tesseract-ocr # 안정화 버전 4.1, 추론 정확도 낮음.
sudo apt-get install tesseract-ocr
sudo apt install libtesseract-dev

build and run

  • g++로 컴파일한다.
g++ -O3 -std=c++11 OCR_depth.cpp $(pkg-config --cflags --libs opencv4 tesseract) -o OCR_depth
./OCR_depth ./resource/image_00001.png

code

#include <string>
#include <tesseract/baseapi.h>
#include <leptonica/allheaders.h>
#include <opencv2/opencv.hpp>
using namespace std;
using namespace cv;

int main(int argc, char* argv[]) {
    if (argc != 2) {
        cout << "Usage: " << argv[0] << " <image_path>" << endl;
        return 1;
    }
    string outText, imPath = argv[1];
    Mat im = cv::imread(imPath, IMREAD_COLOR);
    if (im.empty()) {
        cout << "Failed to read the image." << endl;
        return 1;
    }
    tesseract::TessBaseAPI *ocr = new tesseract::TessBaseAPI();
    ocr->Init(NULL, "eng", tesseract::OEM_LSTM_ONLY);
    ocr->SetPageSegMode(tesseract::PSM_AUTO);
    ocr->SetImage(im.data, im.cols, im.rows, 3, im.step);
    ocr->SetSourceResolution(197); // image resolution (warning: invalid resolution 0 dpi. Using 70 instead. Estimatin resolution as 197)
    outText = string(ocr->GetUTF8Text());
    cout << outText;
    ocr->End();
    return 0;
}

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