We describe a method of displaying an image holographically using a spatial light modulator (SLM), the SLM having a plurality of pixels, the method including: displaying a diffraction pattern on the pixels of the SLM; and illuminating the pixels such that light diffracted by said diffraction pattern on the SLM pixels includes a content of said displayed image. A variation in brightness of said displayed image across the displayed image is modulated by an intensity envelope determined by the diffraction pattern of an individual said pixel, for example a sinc envelope. The method further includes moving a peak or centre of gravity of the intensity envelope away from a zero order spot and towards a centre of the displayed image by imposing a pattern of phase delay across the SLM pixels, the pattern of phase delay repeating at a spatial interval corresponding to a pixel interval of the SLM.