Due to increasing LSI pattern density, the minimum feature size on reticle is becoming less than 0.5 μm. In order to write such a fine pattern, highly accurate proximity effect correction must be carried out. However, the correction for the reticle takes much more time than correction in the case of the direct writing system, because of the larger writing area for the reticle fabrication. One of the solutions is a real-time correction hardware system, for which a hardware system for convolution is required. This paper discusses the convolution system we have developed based on the representative figure method.