Deduplication on client instead of server

When a client is performing a file or image backup it seems all files are copied to the server first and then the server is doing the deduplication. Is that correct? Is it possible to perform the dedublication already on the client and transferring only those files which are not already on the server (from another client for example).

I don’t know if it is possible but that would require a lot of memory on the client side I would think.

i think hash by block does it , like for internet incremetmental