OpenCV is a library for processing image data.
The cloud in this case is anything that's on the Internet.
So is that just the same as saying how can I put some kind of data on the Internet?
If so then you could either make your Pi accessible from the Internet (port forwarding on your local router and provide some kind of service to make the data available), or upload to a web based service.
If you wanted a true cloud provider then perhaps something like AWS (Amazon Web Services).
I haven't used AWS, but they do provide an IoT guide at: https://docs.aws.amazon.com/iot/latest/ ... setup.html