**4. Conclusion**

In this chapter, we first propose a robust lossless data hiding via the feature-based bit embedding (FBBE) algorithm based on integer wavelet transform (IWT). Data bits can be effectively carried by the IWT blocks via the FBBE algorithm and the hidden message can be successfully identified later at the receiver. Moreover, the FBBE algorithm can completely recover the host media if the marked image remains intact, and extract (most part of) the hidden message if manipulations were intentionally (or unintentionally) altered to the marked images. In addition, we employ a smart arrangement of the IWT coefficients so as to provide a high-capacity lossless data hiding scheme. Simulations validate that the marked images generated by the proposed FBBE algorithm are robust to a variety of attacks such as JPEG2000, JPEG, cropping, noise additions, (colour) quantization, bits truncation, brightness/contrast, mean/median filtering, and inversion. Furthermore, the payload and PSNR provided by the proposed two methods outperform those provided by existing schemes.

The proposed two methods can be extended to color images by embedding data bits in the RGB system separately. In addition, to further enlarge the hiding storage of the FBBE algorithm, an extra one (or two) data bits could be hidden in each IWT coefficients block during data embedment. However, a tradeoff between PSNR and payload size may be a problem with this algorithm. These issues will be discussed in detail in future work. Furthermore, to reduce memory space and transmission delay, the decreasing of the overhead bits will be our future study.
