1. An integrated circuit comprising: a pixel identifying unit that extracts a target partial image formed of a pixel of interest and adjacent pixels from input image data, determines a character of the pixel of interest based on the pixel of interest and the adjacent pixels, and generates identification information indicating a result of determination on the character; and a density converting unit that converts a density of a pixel of the image data based on a contour extraction function or an edge density reducing function on the image data by using the identification information.