Merge pull request #28968 from Prasadayus:Identity_function_fix_for_0D

Fixes the issue for Identity functions for 0D #28968

Closes https://github.com/opencv/opencv/issues/25763

### 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
- [x] There is accuracy test, performance test and test data in opencv_extra repository, if applicable
      Patch to opencv_extra has the same branch name.
- [x] The feature is well documented and sample code can be built with the project CMake

modules/python/src2/cv2_util.cpp

@@ -6,6 +6,25 @@
 PyObject* opencv_error = NULL;
 cv::TLSData<std::vector<std::string> > conversionErrorsTLS;
 
+int cvDepthToNumpyType(int depth)
+{
+    const int f = (int)(sizeof(size_t)/8);
+    return depth == CV_8U ? NPY_UBYTE : depth == CV_8S ? NPY_BYTE :
+           depth == CV_16U ? NPY_USHORT : depth == CV_16S ? NPY_SHORT :
+           depth == CV_32U ? NPY_UINT32 : depth == CV_32S ? NPY_INT32 : depth == CV_64S ? NPY_INT64 :
+           depth == CV_32F ? NPY_FLOAT : depth == CV_64F ? NPY_DOUBLE : depth == CV_16F ? NPY_HALF :
+           depth == CV_Bool ? NPY_BOOL : f*NPY_ULONGLONG + (f^1)*NPY_UINT;
+}
+
+int numpyTypeToCvDepth(int typenum)
+{
+    return typenum == NPY_UBYTE ? CV_8U : typenum == NPY_BYTE ? CV_8S :
+           typenum == NPY_USHORT ? CV_16U : typenum == NPY_SHORT ? CV_16S :
+           typenum == NPY_INT ? CV_32S : typenum == NPY_UINT32 ? CV_32U : typenum == NPY_INT32 ? CV_32S :
+           typenum == NPY_HALF ? CV_16F : typenum == NPY_FLOAT ? CV_32F : typenum == NPY_DOUBLE ? CV_64F :
+           typenum == NPY_BOOL ? CV_Bool : -1;
+}
+
 using namespace cv;
 
 //======================================================================================================================