DH-LZW: LOSSLESS DATA HIDING IN LZW COMPRESSION (TP-P5)

Author(s) : Hiuk Jae Shim (Sungkyunkwan University, Korea) Jinhaeng Ahn (Sungkyunkwan University, Korea) Byeungwoo Jeon (Sungkyunkwan University, Korea)

Abstract : LZW is one of the well-known lossless compression methods. Since it has several remarkable features such that coding is simple, prior analysis on source is unnecessary, and the whole code table is not sent to its decoder, LZW is widely used in many applications. GIF, TIFF, and PDF (compressing images) are good examples of them. In spite of its reputation on compression, however, few data hiding methods are directly applied to LZW itself. This may be due to few redundancies remained in losslessly compressed data: therefore there is not enough room available for data hiding. Most of existing data-hiding methods are lossy, however, lossless approach is preferred to the lossy one. In this paper, we propose the DH-LZW method that embeds message in a lossless manner. Through this paper, modifiable elements of LZW for data hiding are introduced and a way to handle them is proposed. Experiments show very promising results.

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