Hi and welcome to the forum!
OpenCV is essentially a C/C++ library (with bindings for other programming languages like Python etc. - but C# is not officially among them) - how are you using it in C#? Do you use DllImport to address OpenCV 1 functions or are you using Emgu (www.emgu.com)? In the latter case what you’d need to do is copy the image bytes into a byte array and assign this to the Emgu.CV.Image's Bytes member. The posts in this thread will help you with that.