1. An image forming apparatus comprising: a photosensitive member; an exposure device which is configured to expose the photosensitive member based on image data to form a latent image on the photosensitive member; a conveyance member which is configured to convey a recording medium; an image forming unit which is configured to develop the latent image by developer to form an image on the recording medium and to form a plurality of density detection images on the conveyance member by developer, wherein the density detection images include: a first density detection image corresponding to first image data which includes at least one of image data of a thin line and image data of an isolated pixel; and a second density detection image corresponding to second image data which includes image data different from the image data of the thin line and different from the image data of the isolated pixel and has a pixel density higher than that of the first image data; a density detection unit which is configured to detect densities of the first density detection image and the second density detection image; and an exposure setting unit which is configured to: compare a first detected image density of the first density detection image and a first reference density corresponding to the first density detection image, and compare a second detected image density of the second density detection image and a second reference density corresponding to the second density detection image; and set, as an exposure amount of the exposure device for each of the image data of the thin line, the image data of the isolated pixel and the second image data, an exposure amount which is increased or decreased by an amount from a reference exposure amount for corresponding one of the image data of the thin line, the image data of the isolated pixel and the second image data, according to a condition based on a combination of respective comparison results between the first detected image density and the first reference density and between the second detected image density and the second reference density.