An image processing apparatus successively counts numbers of continuous blocks starting from a left end in view of a number of color(s) forming each block and the color of a preceding block. In this counting, when a first block formed of two colors is input, then second block formed of one of the two colors of the first block is input and then blocks formed of the same one color as the second block are continuously input (second to fourth), the image processing apparatus handles the second to fourth blocks as one-color blocks continuing after the two-color block, and encodes the first to fourth blocks into a code indicating identification information to the effect, a continuation number of the two-color block, color information of each color, information specifying the color of the one-color block being one of the two colors, and the continuation number of the one-color blocks.