Merge remote-tracking branch 'upstream/3.4' into merge-3.4

diff --cc doc/opencv.bib
index d0661e8,bace4c6..3e22e8a
--- 1/doc/opencv.bib
--- 2/doc/opencv.bib
+++ b/doc/opencv.bib
@@@ -1301,36 -1278,11 +1301,44 @@@
    pages={281--305},
    year={1987}
  }
+ @article{Bolelli2021,
+   title={One DAG to Rule Them All},
+   author={Bolelli, Federico and Allegretti, Stefano and Grana, Costantino},
+   journal={IEEE Transactions on Pattern Analysis and Machine Intelligence},
+   year={2021},
+   publisher={IEEE},
+   doi = {10.1109/TPAMI.2021.3055337}
+ }
 +@inproceedings{liao2020real,
 +  author={Liao, Minghui and Wan, Zhaoyi and Yao, Cong and Chen, Kai and Bai, Xiang},
 +  title={Real-time Scene Text Detection with Differentiable Binarization},
 +  booktitle={Proc. AAAI},
 +  year={2020}
 +}
 +@article{shi2016end,
 +  title={An end-to-end trainable neural network for image-based sequence recognition and its application to scene text recognition},
 +  author={Shi, Baoguang and Bai, Xiang and Yao, Cong},
 +  journal={IEEE transactions on pattern analysis and machine intelligence},
 +  volume={39},
 +  number={11},
 +  pages={2298--2304},
 +  year={2016},
 +  publisher={IEEE}
 +}
 +@inproceedings{zhou2017east,
 +  title={East: an efficient and accurate scene text detector},
 +  author={Zhou, Xinyu and Yao, Cong and Wen, He and Wang, Yuzhi and Zhou, Shuchang and He, Weiran and Liang, Jiajun},
 +  booktitle={Proceedings of the IEEE conference on Computer Vision and Pattern Recognition},
 +  pages={5551--5560},
 +  year={2017}
 +}
 +@article{umeyama1991least,
 +  title={Least-squares estimation of transformation parameters between two point patterns},
 +  author={Umeyama, Shinji},
 +  journal={IEEE Computer Architecture Letters},
 +  volume={13},
 +  number={04},
 +  pages={376--380},
 +  year={1991},
 +  publisher={IEEE Computer Society}
 +}

diff --cc modules/dnn/src/layers/flatten_layer.cpp
Simple merge

diff --cc modules/dnn/src/onnx/onnx_importer.cpp
Simple merge

diff --cc modules/dnn/test/test_onnx_conformance_layer_filter__halide_denylist.inl.hpp
index 344e560,08938c9..72900a8
--- 1/modules/dnn/test/test_onnx_conformance_layer_filter__halide_denylist.inl.hpp
--- 2/modules/dnn/test/test_onnx_conformance_layer_filter__halide_denylist.inl.hpp
+++ b/modules/dnn/test/test_onnx_conformance_layer_filter__halide_denylist.inl.hpp
@@@ -53,16 -17,8 +53,10 @@@
  "test_elu",
  "test_elu_default",
  "test_exp",
- "test_flatten_axis0",
- "test_flatten_axis2",
- "test_flatten_axis3",
- "test_flatten_negative_axis1",
- "test_flatten_negative_axis2",
- "test_flatten_negative_axis4",
 +"test_floor",
  "test_leakyrelu",
  "test_leakyrelu_default",
 +"test_log",
  "test_logsoftmax_axis_1",
  "test_logsoftmax_axis_1_expanded",
  "test_logsoftmax_default_axis",

diff --cc modules/dnn/test/test_onnx_conformance_layer_filter__openvino.inl.hpp
Simple merge

diff --cc modules/dnn/test/test_onnx_conformance_layer_filter_opencv_all_denylist.inl.hpp
index 9e4253a,c9966f1..dd09659
--- 1/modules/dnn/test/test_onnx_conformance_layer_filter_opencv_all_denylist.inl.hpp
--- 2/modules/dnn/test/test_onnx_conformance_layer_filter_opencv_all_denylist.inl.hpp
+++ b/modules/dnn/test/test_onnx_conformance_layer_filter_opencv_all_denylist.inl.hpp
@@@ -42,13 -7,6 +42,7 @@@
  "test_castlike_FLOAT_to_STRING_expanded",
  "test_castlike_STRING_to_FLOAT_expanded",
  "test_concat_1d_axis_negative_1",
- "test_flatten_axis0",
- "test_flatten_axis2",
- "test_flatten_axis3",
- "test_flatten_negative_axis1",
- "test_flatten_negative_axis2",
- "test_flatten_negative_axis4",
 +"test_div_uint8",  // output type mismatch
  "test_logsoftmax_default_axis",
  "test_maxpool_2d_dilations",
  "test_maxpool_2d_same_lower",

diff --cc modules/imgproc/include/opencv2/imgproc.hpp
Simple merge

diff --cc modules/imgproc/src/thresh.cpp
Simple merge

diff --cc modules/imgproc/test/test_color.cpp
Simple merge

diff --cc modules/imgproc/test/test_thresh.cpp
Simple merge