Visual cryptography (VC) is an image-based secret protection mechanism. A new VC approach by random grids, based on Kafri and Keren (1987), has drawn attention recently. With almost all advantages of VC-based image sharing, RG-based image sharing benefits more from no pixel expansion and without the need of predefined code book. In this paper, an RG-based image sharing approach aiming at providing a fast-encoding version is presented. The experimental results show that the proposed approach performs faster than the previous work.