To provide a coding method and a coding unit that can conduct coding at a high-speed with a minimum scale of a memory configuration.

A pixel of a coding object line received through an image bus is compared with a pixel included at least in one preceding line corresponding to data of one preceding line to the coding object line. When the pixels are coincident as a result of the comparison, the data of at least one preceding line corresponding to data of one preceding line are used for the data of the coding object line and the coding is applied to the data.