Efficient method for accessing image data stored in a cloud

A device transmits a request to access image data stored in a cloud and then receives an access path to the image data. If the image data are in a first data format, the device reads the image data via the access path, converts them into the second data format, and stores the converted image data in the cloud. It also modifies the access path according to a modification rule and stores the modified access path in the cloud. If the image data are in the second data format, the device either always reads the image data in the second data format via the access path or checks whether a special instruction has been defined. On the basis of the special instruction, the device either reads the image data in the second data format via the access path or remodifies the access path using the modification rule.