Image data processing apparatus and method using error diffusion

An apparatus and method are provided for processing image data using error diffusion. The apparatus and method decode image data compressed in a joint photographic experts group (JPEG) format, convert the image data into color coordinates without storing the image data in a memory, and perform a binarization by calculating error values in accordance with the image data in the unit of block to generate a final output data which is 1 bit long. Since the apparatus and method for processing image data using error diffusion do not require an operation of transmitting and storing the image data to a system memory through a DMA controller, the performance of a system is improved. Also, since the memory does not require a large storage space to store the decoded image data, its utility is improved.