A novel road sign detection method using specific color-pair information is presented. First, the input color image is enhanced in CIE L*a*b* color space to highlight blue color areas. Then, a quaternion convolution based on specific color-pair edge extraction technique proposed in our previous works is applied to obtain useful color edge information. Next, a connected component analysis process together with a verification process is performed for filtering out noisy areas. Simulation results show our method has good accuracy and efficiency, which can provide efficient information for road sign recognition.