原始观点

Format-Preserving Encryption

4 The Rank-then-Encipher Approach

引用1

Hybrid diffusion-based visual image encryption for secure cloud storage
2.2 Sum-preserving encryption
Bellare introduced the concept of format-preserving encryption (FPE), a technique that assures the consistency of data formats throughout the encryption process [49]. Subsequently, Tajik further refined the concept by developing sum-preserving encryption (SPE), a method that guarantees the invariance of pixel sums before and after the encryption process [30]. The specific steps of SPE are outlined as follows:

可以看到引用时的表达更加通俗易懂了。
原始观点中，形式化的内容偏多，理解上相对引用1要费力一些。

引用2

HF-TPE: High-Fidelity Thumbnail- Preserving Encryption
算法1

这里的算法描述略显抽象，但是，除此之外还有对应的文字描述，二者配合起来，就显得容易多了。

和保持的基本理解：

引用3

Balancing Image Privacy and Usability with Thumbnail-Preserving Encryption
直接进入简单易懂的模式