1. An image processing apparatus that converts a first image having a plurality of pixels and expressed in a first calorimetric system constituted of a plurality of color components with each of the pixels corresponding to one of the color components to a second image expressed in a second calorimetric system constituted of a plurality of color components which are different from the first calorimetric system, comprising: a similarity decision-making device that determines levels of similarity manifesting at a processing object pixel in the first image along a plurality of directions; and a new component generating device that generates color information representing at least one of the color components constituting the second calorimetric system at a pixel in the second image corresponding to the processing object pixel through a weighted addition executed by using predetermined coefficients to add together a plurality of sets of color information selected from color information present at the processing object pixel and color information present at pixels near the processing object pixel, based upon results of a decision made with regard to the levels of similarity by the similarity decision-making device.