Algorithm 2: Extraction and recovery pseudocode

$foreach block {b^{\prime }}_{i }in T^{\prime } do$   $if H_m-L_m \le 4 then$   /* non-embeddable block */     $\mathrm{Do} \mathrm{nothing};$   $else if b_i is first embeddable block then$     $\mathrm{get} \mathrm{the} \mathrm{dictionary} D \mathrm{number};$   $else$     $foreach pixel x\prime {\prime }_i in b{\prime }_i do$       $\mathrm{get} \mathrm{the} \mathrm{first} H_m and L_m$;       $if {x^{″}}_i=H_m then$        $P_v=x\prime {\prime }_i-H_m;$       $else$        $P_v=x\prime {\prime }_i-L_m;$       $end$       $\mathrm{find} \mathrm{the} \mathrm{symbol} S_p in D;$       $S=S+S_p;$     $end$   $end$ $end$