Modifying data from a surgical robotic system

A data volume modification system for a surgical robotic system for controlling a data modifier to reduce overall a data volume of a data stream in the surgical robotic system, the surgical robotic system comprising a robot having a base and an arm extending from the base to an attachment for an instrument, the arm comprising a plurality of joints whereby the configuration of the arm can be altered, the system comprising:

• a receiver configured to receive a data stream captured by the surgical robotic system, the data stream comprising data relating to a surgical procedure and having a first data volume;
• a feature detector configured to identify a feature in the received data stream indicative of an event in the surgical procedure;
• a data modifier configured to selectively modify the received data stream to generate a modified data stream;
• and
• an output configured to output the modified data stream;
• wherein the system is configured to, in dependence on the identified feature, determine selected data within the received data stream for which data fidelity is to be retained and, in dependence on the determined selected data, to control the data modifier to move between:
• an active state in which the data modifier is arranged to modify the received data stream to generate the modified data stream, where the modified data stream has a second data volume that is smaller than the first data volume whilst retaining the data fidelity of the determined data, and
• an inactive state in which the data modifier is arranged not to modify the received data stream, thereby leaving the received data stream unmodified.