In order to reduce the transfer time of medical data, an apparatus for transferring medical data from a clinical-data infrastructure to a cloud-service provider. The apparatus comprises an input unit, a processing unit, and an output unit. The input unit is configured to receive, at the clinical-data infrastructure, medical data to be sent to the cloud-service provider with at least one available cloud service for analyzing the medical data. The processing unit is configured to select a data reduction algorithm from one or more data reduction algorithms based on a data reduction requirement of the at least one available cloud service, and to apply the selected data reduction algorithm to the medical data to generate reduced medical data. The output unit is configured to transmit the reduced medical data to the cloud-service provider.