1. An imaging device that combines plural pieces of image data so as to generate image collage data, the imaging device comprising: an imaging unit that images a subject so as to repeatedly obtain first image data; an image processing unit that performs image processing on the first image data so as to obtain second image data; a first storage unit in which the first image data and the second image data are stored; an image analysis detector that analyzes a feature of the first or second image data stored in the first storage unit and that outputs an analysis result that includes information on the subject and a composition; a scenario generation processor that generates scenario data on the basis of an analysis result of the image analysis detector; a scenario changing processor that performs setting so as to change the scenario data generated by the scenario generation processor; and an image collage processing unit that determines arrangement of images on the basis of the scenario data and that combines a plurality of pieces of first or second image data stored in the first image storage unit that has undergone color conversion processing or luminance conversion processing, so as to generate one piece of image collage data placed at a prescribed position in accordance with the determined arrangement of images, wherein after the scenario generation processor has generated the scenario data on the basis of the analysis result of the image analysis detector, when the scenario changing processor performs setting so as to change the scenario data, the scenario data is prioritized, and when the scenario changing processor does not perform setting so as to change the scenario data, the scenario data is updated on the basis of the analysis result of the image analysis detector, in synchronization with a change in the image data stored in the first storage unit.