1. An image generating apparatus comprising: a memory in which one or more programs are stored; and a processor, wherein the one or more computer programs cause the processor to perform operations to: select an image as a reference image from a plurality of images; select a most recent layout selected for a composite image generated most recently as a layout for a new composite image; extract at least one related image from the plurality of images, which is related to the reference image selected from the plurality of images, by selecting the at least one related image from the plurality of images; and generate the new composite image different according to the selected reference image, by using the selected reference image and the extracted at least one related image based on a layout, the layout comprising a definition of at least one kind of information of a background image, the number of images to be used to generate the composite image, a size of each image to be used to generate the composite image, and positional relation among images to be used to generate the composite image.