## 1 Introduction
[28] used a quantum logistic map to diffuse the relationship of pixels, employed a two-dimensional logistic map to modify the values of diffused pixels, and exploited random circular shift operation to rearrange the bits of each encrypted pixel. [PERSON] et al. [29] introduced an improved permutation-diffusion architecture, which included three stages: plain pixel-related swapping confusion, diffusion, and plain pixel-related swapping confusion. However, a ciphertext or cipher image can easily be deciphered by chosen plaintext and ciphertext attacks [30; 31; 32] if the permutation operation just changes the position of the pixel in the permutation stage, and the pseudorandom sequence generated by the chaotic system is independent of the plaintext and diffusion process. To avoid attackers cracking cryptosystems by using an order from top to bottom and from left to right, a variety of image encryption algorithms using bit-level permutation have been proposed. [PERSON] et al. [33] proposed a novel bit-level image encryption algorithm via chaotic maps, such as a technique that uses piecewise linear chaotic maps (PWLCM) and bit-level permutations to achieve this goal. In [34], [PERSON] et al. proposed a bit-level permutation scheme for image encryption that is based on both Arnold's cat and logistic maps. In [35], a new bit-level encryption algorithm was developed based on spatiotemporal nonadjacent coupled map lattices that made it possible for any bit in pixels to break the limit of its bit plane without extra space in the permutation process. The permutation process at the bit level is actually able to simultaneously change the positions and gray values of pixels for high-resolution images; however, this requires more computational resources which naturally increases the iterative times of chaotic systems. On the other hand, low-dimensional chaotic maps, such as the logistic map, are easy to use and require fewer computational resources. For high security considerations, low-dimensional chaotic systems are rarely applied for ciphering confidential images with high security requirements. In addition, some general methods can decipher these images, such as phase-space reconstruction or nonlinear prediction, but it is difficult to decipher images with high-dimensional chaotic systems. High-dimensional chaotic systems, especially hyperchaotic systems, have a larger key space, better sensitivity, more complex dynamic characteristics, and randomness. Consequently, a hyperchaotic system is especially appropriate for data protection with high security considerations [36; 37; 38; 39; 40]. In 2008, [PERSON] and [PERSON] [36] proposed a hyperchaos-based image encryption algorithm using pixel-level permutation; although this algorithm has the advantage of a large key space, [PERSON] and [PERSON] [37] demonstrated that it could not resist chosen plaintext and ciphertext attacks due to the permutation process being at the pixel level. Further, hyperchaos-based image encryption algorithms with DNA encoding and genetic recombination were separately presented by [PERSON] et al. [38] in 2013, and [PERSON] and [PERSON] [39] in 2016. Similarly, complex permutation and ciphering processes demand much greater consumption of computational resource in order to satisfy high security requirements. According to research achievements and valuable experiences from the works listed in this paper, a cloud image data protection algorithm with a multilevel encryption scheme and automated-selection mechanism was developed. The proposed algorithm was designed to work with all image types regardless of their features. The automated-selection mechanism commonly used nowadays, which is a simple sliding window, improves the efficiency when the cryptosystem is used to cipher big images and other types of images not considered by other mechanisms, such as 4K and HD images.