To suppress the quality deterioration of a read image by correcting the fluctuation of an image signal level caused by a cross-talk phenomenon through image processing.

An image processing apparatus 100 employing an image element reading image data and including an image signal transfer function for a plurality of pixel columns comprises an A/D converting unit 103 for converting the image data into digital data; a shading processing unit 107 for performing shading processing upon the converted image data; and an image signal correcting unit 106, provided before the shading processing unit 107, for classifying the image data into prescribed patterns based on a pixel value of an adjacent pixel of the same pixel column as a concerned pixel of the image data and performing different correction processing, regarding an image signal value of the concerned pixel, for each of the classified patterns.