1. An image processing apparatus for determining a non-defective item by comparing a multivalued image obtained by picking up an image of a determination target object with a multivalued image group of non-defective items, the image processing apparatus comprising: a non-defective item image acquisition device that obtains a plurality of first multivalued images as color images of a plurality of non-defective items picked up by an image pickup device; an edge intensity calculation device that calculates edge intensities in two different directions for each pixel and each color component in the obtained first multivalued images; a mean value calculation device that calculates a mean value of the edge intensities in two different directions for each pixel and each color component in the first multivalued images, based on the calculated edge intensities; a distribution region calculation device that calculates an intercorrelation distribution region of the edge intensities in two different directions for each pixel and each color component in the first multivalued images with the calculated mean value being the center; a multivalued image acquisition device that obtains a second multivalued image as a color image of the determination target object picked up by the image pickup device; an image edge intensity calculation device that calculates edge intensities in two different directions for each pixel and each color component in the obtained second multivalued image; and a determination device that determines whether the calculated edge intensities for each pixel and each color component in the second multivalued image are included in the calculated intercorrelation distribution region of the edge intensities for each pixel and each color component in the first multivalued images or not, and wherein the edge intensity calculation device is configured to calculate the edge intensities in two directions of a row direction and a column direction in a two-dimensional image.