1. An image processing apparatus comprising: a level-value-limit smoothed-image creating unit that creates a plurality of first smoothed images corresponding to a target region of a first image including a plurality of pixels from first image information created from the first image, by applying low-pass filters to which different level value ranges are set respectively, to the target region and calculating an average value of level values which are of a plurality of pixels included in the target region and are for each of the level value ranges; a level-value combining unit that selects a part out of the first smoothed images based on a level value of a target pixel included in the target region and combines the selected part on level values corresponding to the target pixel to create a level value combined image; and a smoothed-image creating unit that smoothed image by combining the first image and the level-value combined image using a combining ratio determined on a basis of second image information which is created from the first image and different from the first image information.