Lu et al. proposed a dual-image-based reversible data hiding method using center folding strategy in 2015. The method used a fixed value to decide the hiding capacity. The secret data transformed by decimal system and folded by using center folding strategy. The folded secret data then hidden into two stego-images. The hiding capacity of Lu et al.'s scheme is fixed that is non-flexibility. Thus, this paper applies an interval scale strategy to dynamically change the hiding payload. The proposed scheme divides the original image into several non-overlap blocks sized 1×2. Then, the scheme calculates the difference between two pixels in the block. The interval scale table is used to determine the hiding bits of the block to control the image quality and to obtain higher hiding capacity. The experimental results show that the proposed scheme can get higher capacity.