  We propose a reversible data hiding (RDH) method in compressible encrypted
images called the encryption-then-compression (EtC) images. The proposed method
allows us to not only embed a payload in encrypted images but also compress the
encrypted images containing the payload. In addition, the proposed RDH method
can be applied to both plain images and encrypted ones, and the payload can be
extracted flexibly in the encrypted domain or from the decrypted images.
Various RDH methods have been studied in the encrypted domain, but they are not
considered to be two-domain data hiding, and the resultant images cannot be
compressed by using image coding standards, such as JPEG-LS and JPEG 2000. In
our experiment, the proposed method shows high performance in terms of lossless
compression efficiency by using JPEG-LS and JPEG 2000, data hiding capacity,
and marked image quality.
