A processor system processes image data for rendering a virtual environment for a user present in a real environment. The system receives head tracking data indicative of the orientation of the head of the user. An image processor generates image data for rendering a viewport of the virtual environment on a display system based on the head tracking data. A real-view area is defined in the virtual environment, having at least one boundary. The boundary corresponds to predetermined coordinates in the virtual environment. Thereby a corresponding part of the real environment is made visible in the real-view area, the part showing the real environment as perceived from the user head pose. Effectively the virtual environment is augmented by integrating part of the real environment via the real-view area.