Conference presentation

1. Medical Image Watermarking with Tamper Detection and Recovery Jasni Mohamad Zain, PhD Universiti Malaysia Pahang

2. Motivation It is becoming easier and easier to tamper with digital image in ways that are difficult to detect. For example, Figure 1.2 shows two nearly identical images using readily available software (e.g. Adobe Photoshop). The cyst was removed from the image by using the healing brush tool. It is difficult if not impossible to tell which picture is the original and which has been tampered with. If this image were a critical piece of evidence in a legal case or police investigation, this form of tampering might pose a serious problem.

7. Example TABLE 1 MAPPING OF BLOCKS WITH K=23, 26 AND Nb=40 Note that the secret key, k, must be a prime in order to obtain a one to one mapping; otherwise, the period is less than N b and a one to many mapping may occur k B 1 2 3 4 5 6 21 22 23 24 23 24 7 30 13 36 19 4 27 10 33 26 27 13 39 25 11 37 27 13 39 25

10. Embedding Diagram Avg_A s =(I 1 +I 2 +I 3 +…+I 9 )/9 r =a 1 a 2 a 3 a 4 a 5 a 6 a 7 v, p of B Block A Block B 1 2 3 4 5 6 7 8 9 1 2 3 4 5 6 7 8 9

13. Experiment 1 Level 1 Level 2

14. Experiment 2 We used spread tampering and single block tampering ranging from 10% to 50% of the image as shown in Figure 3 with k=3739 for our second experiment to determine recovery rate of our method. Our results showed that we could recover all tampered areas for spread-tampered blocks and the result for single tampered block is shown in Figure 4. Figure 3 Figure 4

15. Results

19. Thank you [email_address]