1. An image forming apparatus which performs image formation of a target image with the use of a first color gamut as a standard color gamut for image formation, comprising: a storage section configured to store a color expansion table indicating a second color gamut wider than the first color gamut; a color conversion section configured to convert, when a color in the target image is present outside the first color gamut, a color value of the color in the target image to a color value of a coloring material used for image formation on the basis of the color expansion table; and an image forming section configured to perform image formation of the target image on the basis of the color value of the coloring material.