1. Visible Watermarking of An Image Using DCT Technique
Presented by Shravan Kumar Reddy EC 84222
M.Tech ACS III sem

2. INTRODUCTION What is Watermarking? Watermarking issues a) Capacity
The optimum amount of data that can be embedded in a
given signal
b) Transparency
Embed data such that it does not perceptually degrade
the underlying content
c) Security
Information embedded has not been tampered, forged
or even removed

3. Classification

4. Why DCT, not DFT or FFT
The DCT concentrates energy into lower order coefficients better than does the DFT for image data.
The DCT is purely real, the DFT is complex (magnitude and phase).
An N-point DCT has the same frequency resolution as closely related to a 2N-point DFT.
Assuming a periodic input, the magnitude of the DFT coefficients is spatially invariant (phase of the input does not matter). This is not true for the DCT.

5. DCT is similar to the Fast Fourier Transform (FFT),
but can approximate lines well with fewer coefficients.

6. 1) ONE DIMENSIONAL DCT :-
For u = 0,1 2,3,……..N-1
Inverse 1D DCT transform
For x = 0,1,2,3,……..N-1.

7. 2-DIMENSIONAL DCT :- Inverse 2-D DCT transform
For u ,v = 0,1,2,3,……,N-1.
Inverse 2-D DCT transform
For x ,y = 0,1,2,3,…….,N-1.

8. SYSTEM IMPLEMENTATION
Application of DCT to host image

9. Application of DCT to watermark image

10. Basic process of addition of watermark

11. Recovery of watermarked image

14. Block-wise addition of watermark

15. Results
Host image
Watermark image

16. Watermarked image

17. Results
Host image
Watermark image

18. Watermarked image

19. Results
Host image
Watermark image

20. Watermarked image

21. Matlab simulation results: Original image Watermark image

22. Matlab simulation results: DCT of original image DCT of watermark image

23. Matlab simulation results:
Addition of two DCT images Watermarked image

24. Visible Watermark Removal

25. Divide watermarked image into non-overlapping 8×8-pixel blocks, and transform these blocks into DCT domain.
Watermarked image block
Watermark image block

26. Applications Copyright protection Photo development labs
Identity cards and passports
Official documents

27. Conclusions
Added watermark do not produce any distortions to the original image.
Added watermark is robust to attacks.

28. References
[1]. “A DCT Domain Visible Watermarking Technique for Images” by JU P. MOHANTY, K. RAMA KRISHNAN, MOHAN KANKANHALLI.
[2]. “A VLSI Architecture for Visible Watermarking in a Secure Still Digital camera (S2DC) Design” by SARAJU P. MOHANTY, NAGARAJAN RANGANATHAN, and RAVI K. NAMBALLA.
[3]. “An Adaptive DCT Domain Visible Watermarking Technique for Protection of Publicly Available Images” by SARAJU MOHANTY, K.R.RAMAKRISHNAN, MOHAN KANKANHALLI
[4]Digital Image Processing Gonzalez

29. Thank You