An image processing apparatus includes a storage device to store a shading pattern in which a condition of gradation values of a target pixel and a plurality of pixels having a predetermined positional relationship with respect to the target pixel are set, a processor to acquire an multiple value image, generate a binary image from the multiple value image, detect a pixel satisfying the condition set in the shading pattern from the multiple value image as a part of a shading, a generate a shading removal pattern for removing the detected shading, based on the multiple value image, generate a shading removal image by applying the shading removal pattern to the binary image, and an output device to output the shading removal image or information generated using the shading removal image.