1. An image processing apparatus comprising: a processor; and a memory storing instructions, the instructions, when executed by the processor, causing the image processing apparatus to perform: receiving target image data representing a target image, which is a processing target of image processing, wherein the target image comprises a reference area arranged at a predetermined position in the target image, the reference area having the same or similar color as or to a specific area in the target image; interpreting the reference area; determining, from a plurality of pixels in the target image, a plurality of first-type pixels having a color value within a specific range, the specific range having a color value that indicates a color of a conversion target; calculating, for each of the plurality of first-type pixels, non-uniformity of color values of a plurality of pixels in a specific surrounding area that includes the first-type pixels; determining, from the plurality of first-type pixels, a second-type pixel of which non-uniformity is a reference value or less, wherein at least one of the first-type pixel and the second-type pixel is determined using an interpretation result of the reference area; and converting a color value of the second-type pixel into a specific color value.