Thank you avra and domasz!
I known the various project to access the old Opencv C API, but it's no more officially supported from 2.4 version onward.
The GoCv project cover a subset of Opencv, I think it's completely hand-written code.
Anyway I will see the links.
In meantime, I have posted on github the 64 bit DLL binaries, and more Lazarus examples.