A data storage system that is adapted for storing image data in digital cameras comprises a temporary data storage circuit coupled, in use, to receive image data from the camera, and a permanent data storage circuit coupled, in use, to receive image data from the temporary data storage circuit. A control circuit is coupled to the temporary data storage circuit and the permanent data storage circuit to effect transfer of image data from the temporary data storage circuit to the permanent data storage circuit upon occurrence of a predetermined event. The permanent data storage circuit may be in the form of a write-once non-volatile memory module, which is replaceable in the storage system. The temporary data storage circuit can be a RAM or Flash memory that temporarily stores a image data from the camera when a picture is taken. Then, the user may review the picture before it is permanently stored upon the occurrence of the predetermined event. The predetermined event may comprise, for example, another picture being taken, removal of power (e.g. turning the camera off), or expiration of a preset time period.