An image forming device for forming an image on an image carrier using a different grayscale reproduction method for each of two or more different attributes contained in portions of the image. The image forming device forms a different standard pattern in one-to-one correspondence with each different attribute contained in the image portions, using a grayscale reproduction method used for reproducing image portions containing the attribute, detects density of each standard pattern formed by the standard pattern forming unit, sets, for each different attribute, a condition for correcting grayscale of the image portions containing the attribute, in accordance with the detected density, and corrects grayscale of the image portions in accordance with each condition set by the correction condition setting unit.