| 摘要 |
An image forming apparatus capable of performing accurate gradation correction in a range of density where measurement by a toner density detection unit is- impossible. A printer unit forms a gradation pattern on an image bearing member. A density detection sensor detects density of the gradation pattern. A first correction value for correcting gradation of the image data is calculated based on density of the gradation pattern, detected by the density detection sensor, and a second correction value for correcting gradation of the image data is calculated based on the estimated condition of toner with which a toner image is formed on the image bearing member. An output gamma correction unit corrects density in a low density range of the toner image based on the first correction value, and corrects density in a high density range of the toner image based on the second correction value.
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