An image rendering apparatus includes a light source unit, a detecting unit, an optical scanner, a light source driving unit, and an adjusting unit. The light source driving unit is configured to control the light source unit in such a way that a rendered image is generated by the scan of the optical scanner inside a scan area scanned by the optical scanner and that a characteristic laser beam is emitted at a position and in a pattern corresponding to a rendered content of the rendered image. The rendered image includes an indicator related to a speed of a vehicle. The light source driving unit is configured to control the light source unit to emit the characteristics detecting laser beam in such a way that a scale for the indicator related to the speed of the vehicle is rendered.