A fast resist image estimation methodology using light intensity distribution is proposed. Recently, some optical proximity effect correction (OPC) methods have been developed. Conventionally, to apply light intensity simulation of OPC, resist image has been simply estimated as a contour at which light intensity distribution is sliced. However, it is difficult to obtain a real resist image with this conventional method because of no consideration of actual resist process. Now, we have developed a new method which can estimate resist image with simple approximate calculation of light intensity distribution. In this method, resist image can be calculated from light intensity distribution using convolution. Using this method, calculation accuracy can be improved twice compared to that with a conventional light intensity slicing method. In this paper, the method is described in detail, then its feasibility to be applied to OPC will be demonstrated.