An image forming apparatus comprising: an engine ; an information processing device ; an image data acquirer ; a color information generator ; a height information generator ; a corrector ; a layer information generator ; a conveyance controller ; a moving controller ; and a builder , wherein the image data acquirer acquires image data representing a three-dimensional image; wherein the color information generator generates, from the image data representing the three-dimensional image acquired by the image data acquirer , color information indicating, on a per-pixel basis, colors of the three-dimensional image; wherein the height information generator generates, from the image data representing the three-dimensional image acquired by the image data acquirer , height information indicating, on a per-pixel basis, heights of the three-dimensional image; wherein the corrector corrects the height information so that surface of the three-dimensional image is covered with the colors indicated by the color information; wherein the layer information generator generates layer information indicating, on a per-layer basis, pixel layouts for building the three-dimensional image whose shape is corrected so that the surface of the three-dimensional image is covered with the colors indicated by the color information, based on the corrected height information and the color information; and wherein the corrector corrects the height information so that the surface of the three-dimensional image is covered with the colors indicated by the color information based on resolution of the three-dimensional image, characterized in that the corrector corrects the height information so as to make a slope angle of a side of the shape of the three-dimensional image substantially equal to an angle of tan -1 ((the height H of a layer)/(the diameter P of the build material in the plane of the layer computed from the inverse of the resolution)). an engine ; an information processing device ; an image data acquirer ; a color information generator ; a height information generator ; a corrector ; a layer information generator ; a conveyance controller ; a moving controller ; and a builder , wherein the image data acquirer acquires image data representing a three-dimensional image; wherein the color information generator generates, from the image data representing the three-dimensional image acquired by the image data acquirer , color information indicating, on a per-pixel basis, colors of the three-dimensional image; wherein the height information generator generates, from the image data representing the three-dimensional image acquired by the image data acquirer , height information indicating, on a per-pixel basis, heights of the three-dimensional image; wherein the corrector corrects the height information so that surface of the three-dimensional image is covered with the colors indicated by the color information; wherein the layer information generator generates layer information indicating, on a per-layer basis, pixel layouts for building the three-dimensional image whose shape is corrected so that the surface of the three-dimensional image is covered with the colors indicated by the color information, based on the corrected height information and the color information; and wherein the corrector corrects the height information so that the surface of the three-dimensional image is covered with the colors indicated by the color information based on resolution of the three-dimensional image, characterized in that the corrector corrects the height information so as to make a slope angle of a side of the shape of the three-dimensional image substantially equal to an angle of tan -1 ((the height H of a layer)/(the diameter P of the build material in the plane of the layer computed from the inverse of the resolution)). <EOS>