High Capacity Lossless Data Hiding in JPEG Bitstream Based on General VLC Mapping
This addresses the need for efficient and distortion-free data hiding in widely used JPEG images, though it appears incremental as it builds on existing reversible data hiding techniques with a new mapping strategy.
The paper tackles the problem of reversible data hiding in JPEG images, which often causes distortions and file size increases, by proposing a novel lossless data hiding scheme that uses variable length code mapping to embed secret data without visual degradation, achieving high embedding capacity and smaller file size increments compared to previous schemes.
JPEG is the most popular image format, which is widely used in our daily life. Therefore, reversible data hiding (RDH) for JPEG images is important. Most of the RDH schemes for JPEG images will cause significant distortions and large file size increments in the marked JPEG image. As a special case of RDH, the lossless data hiding (LDH) technique can keep the visual quality of the marked images no degradation. In this paper, a novel high capacity LDH scheme is proposed. In the JPEG bitstream, not all the variable length codes (VLC) are used to encode image data. By constructing the mapping between the used and unused VLCs, the secret data can be embedded by replacing the used VLC with the unused VLC. Different from the previous schemes, our mapping strategy allows the lengths of unused and used VLCs in a mapping set to be unequal. We present some basic insights into the construction of the mapping relationship. Experimental results show that most of the JPEG images using the proposed scheme obtain smaller file size increments than previous RDH schemes. Furthermore, the proposed scheme can obtain high embedding capacity while keeping the marked JPEG image with no distortion.