1. An image providing device for providing a mosaic image of an original image divided into a plurality of regions, the image providing device comprising: a specifying unit that calculates an edge degree indicating a degree of an edge included in an image of the region and specifies the region whose edge degree is greater than or equal to a predetermined value to be a region including an edge of an image from the plurality of regions; a dividing unit that further divides the specified region into a plurality of regions so that the higher the calculated edge degree of the region, the greater the number of division; an acquisition unit that acquires an image specified by a user; a determination unit that determines a region to which the acquired image is assigned from regions not divided by the dividing unit among the plurality of regions and from the regions formed by being divided by the dividing unit; and a presentation unit that, on the basis of assignment determined by the determination unit, causes a mosaic image in which the acquired image is arranged to be presented.