Image processing apparatus

In an image processing apparatus, a specific local gradation pattern detecting unit detects a specific local gradation pattern in a density distribution of a pixel array in a secondary scanning direction at each one of plural sampling positions along a primary scanning direction in a document image. A crease detecting unit detects a crease on the basis of positions in the primary scanning direction and positions in the secondary scanning direction of plural specific local gradation patterns detected for the plural sampling positions along the primary scanning direction. A crease removing unit removes the detected crease. The specific local gradation pattern has a density distribution that monotonically increases from a background density to a local peak density and monotonically decreases from the local peak density to the background density in the secondary scanning direction.