When you are viewing the remote desktop at the reduced size, Remotix shows you the scaled image. In common case Remotix gets the full-resolution image over the Internet and then reduces it to the smaller size. With server scaling enabled, OS X Screen Sharing server will reduce the image before sending it to you, thus reducing the network traffic.
The server scaling is enabled by default on all Mac-based connections.
To disable server scaling:
See Control or observe a single server for detailed information.