1. A computer implemented method of reducing a first optical distortion introduced by an optical element arranged to reflect light from an image source to a viewer of an optical display system; the method comprising: receiving, by a processing device, image data for display by the optical display system; receiving, by the processing device; an inverse distortion map corresponding to the optical element; rendering, by the processing device, the image data to an image source display buffer prior to display according to coordinates indicated by the inverse distortion map to create an image with a second optical distortion; displaying the created image with the second optical distortion read from the display buffer by the image source, wherein a viewer of the optical display system perceives an image that is substantially distortion free.