Table 11 The pseudocode of the embedding process of one PU partition modes group from 16 ×16-sized CUs

Input: a group containing two PU partition modes, denoted by p = (p₁, p₂), a basis vector b = (b₁, b₂), and a secret digit s in a (2^2 + 3 − 1)-ary notational system

Output: the modified group of p, denoted by p^′

1. F = p ⋅ b = p₁ × b₁ + p₂ × b₂

2. if s ≥ F

3. d = s-F

4. else if s < F

5. d = 2^2 + 3 − 1 − |s − F|

6. end if

7. p_temp = (p₁ + d₁, p₂ + d₂)

8. if (any element of p_templarger than 7 or smaller than 0)

9. for i=0:1:7

10. for j = 0:1:7

11. record all the \( {\mathbf{p}}_l=\left({p}_{l_1},{p}_{l_2}\right)=\left(i,j\right) \)that makes i × b₁ + j × b₂ =  = s, and store them in one set

12. \( \mathbf{P}=\left\{{\mathbf{p}}_l=\left({p}_{l_1},{p}_{l_2}\right),l\in \Big\{1,2,\cdots, k\Big\}\right\} \)

13. end for

14. end for

15. for l=1:1:k

16. calculate the Manhattan Distance md of each element in P from p, i.e. \( \left|{\mathbf{p}}_l-\mathbf{p}\right|=\left|{p}_{l_1}\hbox{-} {p}_1\right|+\left|{p}_{l_2}\hbox{-} {p}_2\right| \)

17. end for

18. \( {\mathbf{p}}^{\prime }=\underset{{\mathbf{p}}_l}{\arg \min}\left(\left|{p}_{l_1}-{p}_1\right|+\left|{p}_{l_2}-{p}_2\right|\right) \)

19. else if

20. p^′ = p_temp

21. end if