There is provided an encoder that enables an image of a field-of-view range of a user to be displayed immediately. The encoder encodes, for a pair of opposite surfaces among a plurality of surfaces of a model for an omnidirectional image, a first composite image obtained by combining an omnidirectional image of a first surface of a high resolution and an omnidirectional image of a second surface of a resolution lower than the high resolution and a second composite image obtained by combining an omnidirectional image of the second surface of the high resolution and an omnidirectional image of the first surface of a low resolution. For example, the present disclosure can be applied to an image display system or the like.