Methods of Integrity Checking Digitally Displayed Data And Display System

In a display system 22, a display 24 comprises a pixel array. Graphical information is drawn to the pixel array and the drawn information is compared by a GIM (Graphics Integrity Monitor) engine 50 to a corresponding signature reference for the graphical information. The integrity of the drawn information is determined based on the comparison. In an embodiment, the pixel array has a viewable area to which the graphical information is drawn. In another embodiment, the pixel array has a viewable area 40 and a non-viewable area 42, the graphical information is predetermined typically at least one non-application specific graphical primitive and is drawn to the non-viewable area. In an embodiment, the signature reference is a pre-calculated value supplied by software to the GIM engine, possibly in conjunction with or separate from the graphical information, e.g. a CRC (Cyclic Redundancy Check) value. In an embodiment, the drawing, comparing, and determining are performed by a GIM implemented in a processor. The arrangement finds typical application in aircraft systems, e.g. display 24 is a flight display (see figure 1).