Patent ID: 8547597

Claim:
An image forming apparatus that forms an image by overlapping a colored first image and a transparent second image formed of transparent ink, the image forming apparatus comprising: an image forming unit that forms the image based on image data by using the colored first image and the transparent second image formed of transparent ink; a pattern creating unit that selects at least two of a plurality of half-tone processes, and that creates pattern data indicating a plurality of concentration patterns created using the selected half-tone processes, respectively; an image formation control unit that controls the image forming unit to form a first concentration pattern based on the pattern data created by the pattern creating unit using the first image, and to form a second concentration pattern, among the concentration patterns formed of the first image, created by at least one of the selected half-tone processes by overlapping the first image and the second image; a reading unit that reads the second concentration pattern formed by overlapping the first image and the second image and the first concentration pattern formed of only the first image that are formed by the image forming unit under the control of the image formation control unit; a tone correcting unit that performs tone correction based on a result of the reading unit when forming the image by the image forming unit; a predicting unit that predicts a first result when the reading unit reads a third concentration pattern formed by a first different half-tone process and formed by overlapping the first image and the second image based on the result obtained by reading the second concentration pattern formed by overlapping the first image and the second image by the reading unit, and that predicts a second result when the reading unit reads a fourth concentration pattern formed by a second different half-tone process and formed of only the first image based on the result obtained by reading the first concentration pattern of only the first image by the reading unit; and a gradation correcting unit that creates a first correction coefficient for gradation correction when the second concentration pattern is formed by overlapping the first image and the second image, and a second correction coefficient when the first concentration pattern is formed of only the first image, on the basis of one of the first result and the second result predicted by the predicting unit.