Reversible Data Hiding Using Two Marked Images Based on Adaptive Coefficient-Shifting Algorithm

Figure 2

Example of data extraction. (a) The stego-block 2, (b) after the adjustment of the maximum pixel value, (c) the difference block, (d) the host block restored from the stego-block 1, (e) the difference block of (d), and (f) after adjustment the maximum pixel value. The hidden digits can be extracted by subtracting the coefficients in (c) from those in (f); respectively, the extracted digits was (103 103 2)₄.

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