### Pull Request Readiness Checklist
See details at https://github.com/opencv/opencv/wiki/How_to_contribute#making-a-good-pull-request
- [x] I agree to contribute to the project under Apache 2 License.
- [x] To the best of my knowledge, the proposed patch is not based on a code under GPL or another license that is incompatible with OpenCV
- [x] The PR is proposed to the proper branch
- [x] There is a reference to the original bug report and related work
- [ ] There is accuracy test, performance test and test data in opencv_extra repository, if applicable
Patch to opencv_extra has the same branch name.
- [ ] The feature is well documented and sample code can be built with the project CMake
The bug has already been reported and explained on the OpenCV forum:
- [optflow-calcopticalflowsparserlof-giving-assertion-error](https://forum.opencv.org/t/cv2-optflow-calcopticalflowsparserlof-giving-assertion-error/4835)
- [calcopticalflowsparserlof-assertion-error-in-initialflow](https://forum.opencv.org/t/calcopticalflowsparserlof-assertion-error-in-initialflow/8669)
The bug is manifested only if 'UseInitialFlow' is set to true and 'ForwardBackwardThreshold' > 0 (enabled).
This change replaces references to a number of deprecated NumPy
type aliases (np.bool, np.int, np.float, np.complex, np.object,
np.str) with their recommended replacement (bool, int, float,
complex, object, str).
Those types were deprecated in 1.20 and are removed in 1.24,
cf numpy/numpy#22607.
Maksim Shabunin
Alexander Smorkalov
Rostislav Vasilikhin
Alex
Mat&I
Tomoaki Teshima
SpaceIm
cudawarped
Sergei Shutov
Giles Payne
AleksandrPanov
Vincent Rabaud
Alexander Alekhin
Suleyman TURKMEN