The present invention performs inplane uneven density correction that suppresses a number of tone correction properties and has few correction residuals. Accordingly, a holding unit of an apparatus of the present invention holds a plurality of tone correction properties respectively corresponding to a plurality of spot diameters that divide a range of a spot diameter of a light exposed on a surface of a photoreceptor by a predetermined interval. In addition a setting unit sets a tone correction property selected from the plurality of tone correction properties based on a spot diameter on the photoreceptor for a pixel corresponding to pixel data C. A correction unit corrects the pixel data C based on the set tone correction property, to generate tone correction data Cc.