To provide an image processing unit that can provide more detailed gradation reproducibility and attain recording with high image quality.

The image processing unit 11 consists of an image input section 13, an image processing section 14, and an image output section 15 or the like. The image processing section 14 consists of an analog/digital conversion section 21, a shading correction section 22, an input gradation correction section 23, a color correction section 24, an image area separation processing section 25, a black generation under color reduction section 26, a spatial filter processing section 27, and a medium tone output gradation processing section 28 or the like that conducts gradation correction processing and error spread processing. The gradation correction processing corrects input 8-bit image data into output 12-bit image data, and the multi-value error spread processing applies 4-bit 16-value error spread processing to the 12-bit image data by each color component.