1. A method of printing a composite black text with a color image forming apparatus using cyan (C), magenta (M), yellow (Y), and black (K) channels, the method comprising: determining whether print data corresponds to a composite black text, wherein the determining comprises determining similarities between a C channel, a M channel, a Y channel, and a K channel of the print data, and determining a degree of flatness of the K channel; searching for a boundary area in the print data if the print data is determined to correspond to the composite black text; and reducing a C channel, an M channel, and a Y channel at the boundary area, and compensating for a K channel by a density of the reduced C, M, and Y channels if the print data is determined to correspond to the composite black text.