backport: refined QRCodeDetector API for OpenCV 4.0

modules/objdetect/include/opencv2/objdetect.hpp

@@ -670,16 +670,46 @@ public:
     void groupRectangles(std::vector<cv::Rect>& rectList, std::vector<double>& weights, int groupThreshold, double eps) const;
 };
 
-class CV_EXPORTS QRCodeDetector
+class CV_EXPORTS_W QRCodeDetector
 {
 public:
-    QRCodeDetector();
+    CV_WRAP QRCodeDetector();
     ~QRCodeDetector();
 
-    void setEpsX(double epsX);
-    void setEpsY(double epsY);
+    /** @brief sets the epsilon used during the horizontal scan of QR code stop marker detection.
+     @param epsX Epsilon neighborhood, which allows you to determine the horizontal pattern
+     of the scheme 1:1:3:1:1 according to QR code standard.
+    */
+    CV_WRAP void setEpsX(double epsX);
+    /** @brief sets the epsilon used during the vertical scan of QR code stop marker detection.
+     @param epsY Epsilon neighborhood, which allows you to determine the vertical pattern
+     of the scheme 1:1:3:1:1 according to QR code standard.
+     */
+    CV_WRAP void setEpsY(double epsY);
+
+    /** @brief Detects QR code in image and returns the quadrangle containing the code.
+     @param img grayscale or color (BGR) image containing (or not) QR code.
+     @param points Output vector of vertices of the minimum-area quadrangle containing the code.
+     */
+    CV_WRAP bool detect(InputArray img, OutputArray points) const;
+
+    /** @brief Decodes QR code in image once it's found by the detect() method.
+     Returns UTF8-encoded output string or empty string if the code cannot be decoded.
 
-    bool detect(InputArray in, OutputArray points) const;
+     @param img grayscale or color (BGR) image containing QR code.
+     @param points Quadrangle vertices found by detect() method (or some other algorithm).
+     @param straight_qrcode The optional output image containing rectified and binarized QR code
+     */
+    CV_WRAP cv::String decode(InputArray img, InputArray points, OutputArray straight_qrcode = noArray());
+
+    /** @brief Both detects and decodes QR code
+
+     @param img grayscale or color (BGR) image containing QR code.
+     @param points opiotnal output array of vertices of the found QR code quadrangle. Will be empty if not found.
+     @param straight_qrcode The optional output image containing rectified and binarized QR code
+     */
+    CV_WRAP cv::String detectAndDecode(InputArray img, OutputArray points=noArray(),
+                                        OutputArray straight_qrcode = noArray());
 protected:
     struct Impl;
     Ptr<Impl> p;
@@ -700,8 +730,8 @@ CV_EXPORTS bool detectQRCode(InputArray in, std::vector<Point> &points, double e
     @param straight_qrcode Matrix of the type CV_8UC1 containing an binary straight QR code.
     */
 CV_EXPORTS bool decodeQRCode(InputArray in, InputArray points, std::string &decoded_info, OutputArray straight_qrcode = noArray());
-//! @} objdetect
 
+//! @} objdetect
 }
 
 #include "opencv2/objdetect/detection_based_tracker.hpp"

modules/objdetect/perf/perf_qrcode_pipeline.cpp

@@ -21,7 +21,8 @@ PERF_TEST_P_(Perf_Objdetect_QRCode, detect)
     ASSERT_FALSE(src.empty()) << "Can't read image: " << image_path;
 
     std::vector< Point > corners;
-    TEST_CYCLE() ASSERT_TRUE(detectQRCode(src, corners));
+    QRCodeDetector qrcode;
+    TEST_CYCLE() ASSERT_TRUE(qrcode.detect(src, corners));
     SANITY_CHECK(corners);
 }
 
@@ -37,8 +38,13 @@ PERF_TEST_P_(Perf_Objdetect_QRCode, decode)
 
     std::vector< Point > corners;
     std::string decoded_info;
-    ASSERT_TRUE(detectQRCode(src, corners));
-    TEST_CYCLE() ASSERT_TRUE(decodeQRCode(src, corners, decoded_info, straight_barcode));
+    QRCodeDetector qrcode;
+    ASSERT_TRUE(qrcode.detect(src, corners));
+    TEST_CYCLE()
+    {
+        decoded_info = qrcode.decode(src, corners, straight_barcode);
+        ASSERT_FALSE(decoded_info.empty());
+    }
 
     std::vector<uint8_t> decoded_info_uint8_t(decoded_info.begin(), decoded_info.end());
     SANITY_CHECK(decoded_info_uint8_t);
@@ -69,7 +75,8 @@ PERF_TEST_P_(Perf_Objdetect_Not_QRCode, detect)
         rng.fill(not_qr_code, RNG::UNIFORM, Scalar(0), Scalar(1));
     }
 
-    TEST_CYCLE() ASSERT_FALSE(detectQRCode(not_qr_code, corners));
+    QRCodeDetector qrcode;
+    TEST_CYCLE() ASSERT_FALSE(qrcode.detect(not_qr_code, corners));
     SANITY_CHECK_NOTHING();
 }
 
@@ -77,7 +84,6 @@ PERF_TEST_P_(Perf_Objdetect_Not_QRCode, detect)
 PERF_TEST_P_(Perf_Objdetect_Not_QRCode, decode)
 {
     Mat straight_barcode;
-    std::string decoded_info;
     std::vector< Point > corners;
     corners.push_back(Point( 0, 0)); corners.push_back(Point( 0,  5));
     corners.push_back(Point(10, 0)); corners.push_back(Point(15, 15));
@@ -91,7 +97,8 @@ PERF_TEST_P_(Perf_Objdetect_Not_QRCode, decode)
         rng.fill(not_qr_code, RNG::UNIFORM, Scalar(0), Scalar(1));
     }
 
-    TEST_CYCLE() ASSERT_FALSE(decodeQRCode(not_qr_code, corners, decoded_info, straight_barcode));
+    QRCodeDetector qrcode;
+    TEST_CYCLE() ASSERT_TRUE(qrcode.decode(not_qr_code, corners, straight_barcode).empty());
     SANITY_CHECK_NOTHING();
 }
 #endif

modules/objdetect/src/qrcode.cpp

@@ -778,7 +778,15 @@ bool QRCodeDetector::detect(InputArray in, OutputArray points) const
 {
     Mat inarr = in.getMat();
     CV_Assert(!inarr.empty());
-    CV_Assert(inarr.type() == CV_8UC1);
+    CV_Assert(inarr.depth() == CV_8U);
+    int incn = inarr.channels();
+    if( incn == 3 || incn == 4 )
+    {
+        Mat gray;
+        cvtColor(inarr, gray, COLOR_BGR2GRAY);
+        inarr = gray;
+    }
+
     QRDetect qrdet;
     qrdet.init(inarr, p->epsX, p->epsY);
     if (!qrdet.localization()) { return false; }
@@ -788,7 +796,7 @@ bool QRCodeDetector::detect(InputArray in, OutputArray points) const
     return true;
 }
 
-CV_EXPORTS bool detectQRCode(InputArray in, vector<Point> &points, double eps_x, double eps_y)
+bool detectQRCode(InputArray in, vector<Point> &points, double eps_x, double eps_y)
 {
     QRCodeDetector qrdetector;
     qrdetector.setEpsX(eps_x);
@@ -1060,11 +1068,27 @@ bool QRDecode::fullDecodingProcess()
 #endif
 }
 
-CV_EXPORTS bool decodeQRCode(InputArray in, InputArray points, std::string &decoded_info, OutputArray straight_qrcode)
+bool decodeQRCode(InputArray in, InputArray points, std::string &decoded_info, OutputArray straight_qrcode)
+{
+    QRCodeDetector qrcode;
+    decoded_info = qrcode.decode(in, points, straight_qrcode);
+    return !decoded_info.empty();
+}
+
+cv::String QRCodeDetector::decode(InputArray in, InputArray points,
+                                  OutputArray straight_qrcode)
 {
     Mat inarr = in.getMat();
     CV_Assert(!inarr.empty());
-    inarr.convertTo(inarr, CV_8UC1);
+    CV_Assert(inarr.depth() == CV_8U);
+
+    int incn = inarr.channels();
+    if( incn == 3 || incn == 4 )
+    {
+        Mat gray;
+        cvtColor(inarr, gray, COLOR_BGR2GRAY);
+        inarr = gray;
+    }
 
     CV_Assert(points.isVector());
     vector<Point2f> src_points;
@@ -1074,18 +1098,50 @@ CV_EXPORTS bool decodeQRCode(InputArray in, InputArray points, std::string &deco
 
     QRDecode qrdec;
     qrdec.init(inarr, src_points);
-    bool exit_flag = qrdec.fullDecodingProcess();
+    bool ok = qrdec.fullDecodingProcess();
 
-    decoded_info = qrdec.getDecodeInformation();
+    std::string decoded_info = qrdec.getDecodeInformation();
 
-    if (exit_flag && straight_qrcode.needed())
+    if (ok && straight_qrcode.needed())
     {
         qrdec.getStraightBarcode().convertTo(straight_qrcode,
                                              straight_qrcode.fixedType() ?
                                              straight_qrcode.type() : CV_32FC2);
     }
 
-    return exit_flag;
+    return ok ? decoded_info : std::string();
 }
 
+cv::String QRCodeDetector::detectAndDecode(InputArray in,
+                                           OutputArray points_,
+                                           OutputArray straight_qrcode)
+{
+    Mat inarr = in.getMat();
+    CV_Assert(!inarr.empty());
+    CV_Assert(inarr.depth() == CV_8U);
+
+    int incn = inarr.channels();
+    if( incn == 3 || incn == 4 )
+    {
+        Mat gray;
+        cvtColor(inarr, gray, COLOR_BGR2GRAY);
+        inarr = gray;
+    }
+
+    vector<Point2f> points;
+    bool ok = detect(inarr, points);
+    if( points_.needed() )
+    {
+        if( ok )
+            Mat(points).copyTo(points_);
+        else
+            points_.release();
+    }
+    std::string decoded_info;
+    if( ok )
+        decoded_info = decode(inarr, points, straight_qrcode);
+    return decoded_info;
+}
+
+
 }

modules/objdetect/test/test_qrcode.cpp

@@ -66,9 +66,13 @@ TEST_P(Objdetect_QRCode, regression)
 
     std::vector<Point> corners;
     std::string decoded_info;
-    ASSERT_TRUE(detectQRCode(src, corners));
+    QRCodeDetector qrcode;
 #ifdef HAVE_QUIRC
-    ASSERT_TRUE(decodeQRCode(src, corners, decoded_info, straight_barcode));
+    decoded_info = qrcode.detectAndDecode(src, corners, straight_barcode);
+    ASSERT_FALSE(corners.empty());
+    ASSERT_FALSE(decoded_info.empty());
+#else
+    ASSERT_TRUE(qrcode.detect(src, corners));
 #endif
 
     const std::string dataset_config = findDataFile(root + "dataset_config.json", false);
@@ -119,10 +123,11 @@ TEST(Objdetect_QRCode_basic, not_found_qrcode)
     Mat straight_barcode;
     std::string decoded_info;
     Mat zero_image = Mat::zeros(256, 256, CV_8UC1);
-    EXPECT_FALSE(detectQRCode(zero_image, corners));
+    QRCodeDetector qrcode;
+    EXPECT_FALSE(qrcode.detect(zero_image, corners));
 #ifdef HAVE_QUIRC
     corners = std::vector<Point>(4);
-    EXPECT_ANY_THROW(decodeQRCode(zero_image, corners, decoded_info, straight_barcode));
+    EXPECT_ANY_THROW(qrcode.decode(zero_image, corners, straight_barcode));
 #endif
 }
 

samples/cpp/live_detect_qrcode.cpp

@@ -86,6 +86,7 @@ int liveQRCodeDetect()
         return -4;
     }
 
+    QRCodeDetector qrcode;
     TickMeter total;
     for(;;)
     {
@@ -97,11 +98,11 @@ int liveQRCodeDetect()
         cvtColor(frame, src, COLOR_BGR2GRAY);
 
         total.start();
-        bool result_detection = detectQRCode(src, transform);
+        bool result_detection = qrcode.detect(src, transform);
         if (result_detection)
         {
-            bool result_decode = decodeQRCode(src, transform, decode_info, straight_barcode);
-            if (result_decode) { cout << decode_info << '\n'; }
+            decode_info = qrcode.decode(src, transform, straight_barcode);
+            if (!decode_info.empty()) { cout << decode_info << '\n'; }
         }
         total.stop();
         double fps = 1 / total.getTimeSec();
@@ -110,7 +111,7 @@ int liveQRCodeDetect()
         if (result_detection) { getMatWithQRCodeContour(frame, transform); }
         getMatWithFPS(frame, fps);
 
-        imshow("Live detect QR code", frame);
+        imshow("Live QR code detector", frame);
         if( waitKey(30) > 0 ) { break; }
     }
     return 0;
@@ -119,33 +120,34 @@ int liveQRCodeDetect()
 int showImageQRCodeDetect(string in, string out)
 {
     Mat src = imread(in, IMREAD_GRAYSCALE), straight_barcode;
-    string decode_info;
+    string decoded_info;
     vector<Point> transform;
     const int count_experiments = 10;
     double transform_time = 0.0;
-    bool result_detection = false, result_decode = false;
+    bool result_detection = false;
     TickMeter total;
+    QRCodeDetector qrcode;
     for (size_t i = 0; i < count_experiments; i++)
     {
         total.start();
         transform.clear();
-        result_detection = detectQRCode(src, transform);
+        result_detection = qrcode.detect(src, transform);
         total.stop();
         transform_time += total.getTimeSec();
         total.reset();
         if (!result_detection) { break; }
 
         total.start();
-        result_decode = decodeQRCode(src, transform, decode_info, straight_barcode);
+        decoded_info = qrcode.decode(src, transform, straight_barcode);
         total.stop();
         transform_time += total.getTimeSec();
         total.reset();
-        if (!result_decode) { break; }
+        if (decoded_info.empty()) { break; }
 
     }
     double fps = count_experiments / transform_time;
-    if (!result_detection) { cout << "Not find QR-code." << '\n'; return -2; }
-    if (!result_decode) { cout << "Not decode QR-code." << '\n'; return -3; }
+    if (!result_detection) { cout << "QR code not found\n"; return -2; }
+    if (decoded_info.empty()) { cout << "QR code cannot be decoded\n"; return -3; }
 
     Mat color_src = imread(in);
     getMatWithQRCodeContour(color_src, transform);
@@ -166,7 +168,7 @@ int showImageQRCodeDetect(string in, string out)
         cout << "Output image file path: " << out << '\n';
         cout << "Size: " << color_src.size() << '\n';
         cout << "FPS: " << fps << '\n';
-        cout << "Decode info: " << decode_info << '\n';
+        cout << "Decoded info: " << decoded_info << '\n';
 
         vector<int> compression_params;
         compression_params.push_back(IMWRITE_PNG_COMPRESSION);