Abstract. HPDH-LZW is a reversible data hiding scheme based on Lempel-Ziv-Welch (LZW) compression codes. It could achieve better hiding capacity by increasing the number of symbols available to hide secrets and faster hiding and extracting speeds due to the lower computation requirements. HPDH-LZW scheme embeds secret data in LZW compression codes by modifying the value of the compression codes, but the modified LZW compression codes is not continuous so that its data space could not be fully used. To solve this problem, we subdivide the compression codes data space and hide different number of secret data in different subspaces. Guided by the idea we realize an improved reversible data-hiding scheme for LZW codes. Experiments show that the scheme we proposed has greater data hiding capacity without increasing the size of the compression file and computational complexity when compared with HPDH-LZW scheme.

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