A system of transferring of three dimensional (3D) image data is described. A 3D source device (10) provides 3D display signal (56) for a display (13) via a high speed digital interface like HDMI. The 3D display signal has frames constituting the 3D image data according to a 3D video transfer format, in which format the frames comprise at least two different frame types. Each frame has a data structure for representing a sequence of digital image pixel data, and represents a partial 3D data structure. The 3D source device includes frame type synchronization indicators in the 3D display signal. The display detects the frame type synchronization indicators and frame types, and generates the display control signals based on synchronizing the partial 3D data structures in dependence of the frame type synchronization indicators.