HOLOGRAPHIC IMAGE ALIGNMENT

A method of holographic projection. The method comprises projecting at least one calibration image using a first colour holographic channel and a second colour holographic channel. Each calibration image comprises at least one light spot. The method comprises performing the following steps for each calibration image in order to determine a plurality of displacements vectors at a respective plurality of different locations on the replay plane. A first step comprises projecting the calibration image onto the replay plane using a first colour holographic channel by displaying a first hologram on a first spatial light modulator and illuminating the first spatial light modulator with light of the first colour. A second step comprises projecting the calibration image onto the replay using a second colour holographic channel by displaying a second hologram on a second spatial light modulator and illuminating the second spatial light modulator with light of the second colour. It may be said that the first and second hologram correspond to the calibration image. A third step comprises determining the displacement vector between the light spot formed by the first colour holographic channel and the light spot formed by the second colour holographic channel. A fourth step comprises pre-processing an image for projection using the second colour holographic channel in accordance with the plurality of determined displacement vectors.