This paper introduces a PC-based image data processing unit that is composed of preprocessor board and main processor board; The preprocessor contains Inmos A110 processor and efficient H/W architecture for fast mask/logic operations at the speed of video signal rate. It is controlled by the main processor which communicates with the host PC. The main processor board contains TI TMS320C31 digital signal processor, and can access the frame memory of the processor for extra S/W tasks. We test 3*3, 5*5 masks and logic operations on 386/486/DSP and compare the result with that of the proposed unit. The result shows ours are extremely faster than conventional CPU based approach, that is, over several hundred times faster than even DSP.