Lu et al. proposed a dual-image based hiding method uses the center folding strategy and the interval scale in 2018. Their method uses the variable k value to improve the hiding amount and image quality by setting the interval scale, where k is the total number of binary bits that a pixel can be hidden. However, the interval scale in the scheme is manually set, and different types of images need to be manually determined an appropriate interval scale. However, how to find a suitable interval scale is a difficult task. This paper automatically finds the most suitable interval scale table through the preprocessing process, and finds the optimal rules for different images. The experimental results show that the proposed method can effectively increase the amount of hiding payload while maintaining a good image quality.