1. An image processing apparatus, comprising: a dividing unit that divides a tile image including a predetermined number of pixels into pieces of a size of 2×2 pixels each; an identifying unit that identifies a pattern flag indicating an arrangement pattern of color data contained in each piece by sequentially taking each piece divided by said dividing unit as a processing target and comparing the color data of each pixel in the processing target piece, and identifies first color data and color data other than the first color data in each piece, the first color data being color data corresponding to a pixel at a predefined position in each piece; a determining unit that determines whether or not all the pieces, except for a piece consisting of the same color, included in the tile image consist of same two colors; and a generating unit that generates packet data including the pattern flag, the color data on the first color in each piece, and representative colors for reference in the tile image, if said determining unit determines that all the pieces, except for a piece consisting of the same color, included in the tile image consist of same two colors, the representative colors for reference in the tile image being the same two colors.