A head-up display for a vehicle, the head-up display comprising: a picture generating unit arranged to generate a picture on a light receiving surface, wherein the picture generating unit comprises: a light source arranged to emit light; a spatial light modulator arranged to receive the light from the light source and output spatially-modulated light in accordance with a computer-generated hologram represented on the spatial light modulator to form the corresponding picture on the light receiving surface; and a holographic processor arranged to output the computer-generated hologram to the spatial light modulator, wherein the head-up display further comprises: an optical system arranged to image the picture, wherein the optical system comprises: an input arranged to receive light of the picture; an output arranged to output light forming an image of the picture; a first reflective element and second reflective element arranged to guide light from the input to the output along an optical path, wherein the optical path comprises: a first optical path from the input to the second reflective element including a first transmission through a first curved surface of the first reflective element and then a second transmission through a second curved surface of the first reflective element, wherein the radius of curvature of the first surface is not equal to the radius of curvature of the second surface; and second optical path from the second reflective element to the output including a reflection off the second curved surface of the first reflective element. a picture generating unit arranged to generate a picture on a light receiving surface, wherein the picture generating unit comprises: a light source arranged to emit light; a spatial light modulator arranged to receive the light from the light source and output spatially-modulated light in accordance with a computer-generated hologram represented on the spatial light modulator to form the corresponding picture on the light receiving surface; and a holographic processor arranged to output the computer-generated hologram to the spatial light modulator, wherein the head-up display further comprises: a light source arranged to emit light; a spatial light modulator arranged to receive the light from the light source and output spatially-modulated light in accordance with a computer-generated hologram represented on the spatial light modulator to form the corresponding picture on the light receiving surface; and a holographic processor arranged to output the computer-generated hologram to the spatial light modulator, wherein the head-up display further comprises: an optical system arranged to image the picture, wherein the optical system comprises: an input arranged to receive light of the picture; an output arranged to output light forming an image of the picture; a first reflective element and second reflective element arranged to guide light from the input to the output along an optical path, wherein the optical path comprises: a first optical path from the input to the second reflective element including a first transmission through a first curved surface of the first reflective element and then a second transmission through a second curved surface of the first reflective element, wherein the radius of curvature of the first surface is not equal to the radius of curvature of the second surface; and second optical path from the second reflective element to the output including a reflection off the second curved surface of the first reflective element. an input arranged to receive light of the picture; an output arranged to output light forming an image of the picture; a first reflective element and second reflective element arranged to guide light from the input to the output along an optical path, wherein the optical path comprises: a first optical path from the input to the second reflective element including a first transmission through a first curved surface of the first reflective element and then a second transmission through a second curved surface of the first reflective element, wherein the radius of curvature of the first surface is not equal to the radius of curvature of the second surface; and second optical path from the second reflective element to the output including a reflection off the second curved surface of the first reflective element.