1. An image processing apparatus, comprising: a processor configured to control the image processing apparatus to implement: an image retrieving unit that retrieves an image including a symbol; a noise detecting unit that detects individual noise candidates of the image as a detected region; a comparative image retrieving unit that, before noise is removed from the image, retrieves a comparative image that is to be compared with the detection region detected by the noise detecting unit; and a removing unit that, in accordance with comparison results of the detection region with the comparative image, removes from the image one portion of the detection region excluding the other portion of the detection region similar to the comparative image, wherein the comparative image retrieving unit retrieves the comparative image from a comparative image storage unit storing the comparative image indicating at least part of the symbol, wherein the comparative image, when being stored, is associated with information relating to a positional relationship between a position of the detection region and a position of the symbol included in the image, and wherein the removing unit compares the detection region with the comparative image associated with the information relating to the positional relationship between the position of the detection region and the position of the symbol included in the image.