1 Reversible visible watermarking and lossless recovery of original images Source: IEEE transactions on circuits and systems for video technology, vol. 16, no. 11, November 2006 Authors: Yongjian Hu and Byeungwoo Jeon Speaker: Chia-Chun Wu ( 吳佳駿 ) Date: 2007/05/02

2 Outline Introduction Reversible visible watermarking Proposed method Embedding Lossless Recovery Experimental results Conclusions Our proposed method

3 Introduction (1/2) Generally, a visible watermark is translucently laid on the host image and designed to be irreversible so as to resist unintentional modifications or malicious attacks.

4 Introduction (2/2) However, in some potential applications, a visible watermark is first used as a tag or ownership identifier and then needs to be removable. Example: 1. patient’s images 2. remote sensing 3. military imagery

5 Reversible visible watermarking Embedding algorithm Host image Marked-image Extraction algorithm Host imageMarked-image recover SKKU User key (80 bits)

6 The Proposed method − Embedding (1/5) User key (80 bits) = Watermark size (8 bits+8 bits) + Origin position of R (16 bits+16 bits) + D c size (16 bits) + key bit plane level (3 bits) … H=S c ∪ D c W =Binary watermark S =Pixel sequence composed of one-bit pixels on I k Fig. 1. Framework of visible watermark embedding and data hiding.

7 The Proposed method − Embedding (2/5) R I-R Host Image I Watermark W

8 The Proposed method − Embedding (3/5) R W R’ D D c = 010 Hiding Compression

9 The Proposed method − Embedding (4/5) To find S which satisfy |D c |=|S|-|S c | D c = 010, |D c | = R’ LSB of I-R 0 S=0,|S|=1, |S c |=1 X 0 S=00, |S|=2, |S c |=2 X 0 S=000, |S|=3, |S c |=2 X S= S c = |S|=12, |S c |=9 O Payload: H=S c ∪ D c H=

10 The Proposed method − Embedding (5/5) RmRm (I-R) m Watermarked images I m

11 The Proposed method − Lossless Recovery (1/2) To find S c which satisfy |D c |=|S|-|S c | |D c | = R’ LSB of (I-R) m S c = S= |S c |=9, |S|=12 O D c =

12 The Proposed method − Lossless Recovery (2/2) R W D D c = 010 Extraction Decompression R’

13 Experimental results (1/2) Fig. 2. Visibly watermarked images with the MSB plane of R as R D (upper row) and the second MSB plane of R as R D (lower row), respectively.

14 Experimental results (2/2) TABLE I: Performance evaluation. The unit of |D|; |D c |; and |S| is Bytes. N R D and N kb denote the bit plane level of R D and the key bit plane, respectively. The PSNR is calculated without R. (Unit: DB)

15 Conclusions Design for binary watermarks The first work that implements a reversible visible watermarking system.

16 Our proposed method- embedding (1/2) Host Image I Histogram peakzero a=3 b= Watermark W R I-R I’ D

Our proposed method- embedding (2/2) D= 1001 Watermarked images I m I’ a=3 b=6