Hologram calculation method

A hologram engine for calculating a hologram of a target picture comprising a plurality of image points, the hologram engine being arranged to perform a first data processing stage comprising, for a first subset of image points:

• determining, using a point cloud method, a value for every nth pixel of a display device for displaying the hologram, wherein n is greater than 1;
• and
• determining a value for at least some of the other pixels by performing a first interpolation,
• wherein each image point of the first subset has an associated diffraction angle for use in the point cloud method, each diffraction angle being less than a maximum diffraction angle of the display device.

A method of calculating a hologram of a target picture comprising a plurality of image points, the method comprising performing a first data processing stage comprising, for a first subset of image points:

• determining, using a point cloud method, a value for every nth pixel of a display device for displaying the hologram, wherein n is greater than 1;
• and
• determining a value for at least some of the other pixels by performing a first interpolation;
• wherein each image point of the first subset has an associated diffraction angle for use in the point cloud method, each diffraction angle being less than a maximum diffraction angle of the display device.