1. An apparatus for outputting an image using a plurality of chroma-key colors, the apparatus comprising: a chroma-key-color-storage unit that stores the chroma-key colors; a microprocessor unit (MPU) that sets a block where one of the chroma-key colors is applied using a pixel address of a foreground image; and a video controller that generates a composed image comprising a background image and the foreground image using the block set by the MPU, and outputs the composed image.