In this paper, an image processing system we proposed combines the halftone method and image enhancement technique for processing halftone and improving image performance in one pass of the data. The system includes an image input module, an image enhancement module and a halftone module. The image input module sends the original image data to the image enhancement module to enhance the image by filtering. Without storing the result to memory, the halftone module immediately processes the enhanced image data by the algorithm of error diffusion. In our system, the halftone image will be obtained and get improved at the same pass of the data. The system combines two different processes into one step to simplify the hardware architecture and to decrease the access of memory.