• Publications
  • Influence
Context-based, adaptive, lossless image coding
The CALIC obtains higher lossless compression of continuous-tone images than other lossless image coding techniques in the literature and can afford a large number of modeling contexts without suffering from the context dilution problem of insufficient counting statistics as in the latter approach. Expand
PassPoints: Design and longitudinal evaluation of a graphical password system
PassPoints is described, a new and more secure graphical password system, and an empirical study comparing the use of PassPoints to alphanumeric passwords is reported, which shows that the graphical password users created a valid password with fewer difficulties than the alphan numeric users. Expand
A buyer-seller watermarking protocol
  • N. Memon, P. Wong
  • Computer Science
  • IEEE Second Workshop on Multimedia Signal…
  • 7 December 1998
This paper proposes an interactive buyer-seller protocol for invisible watermarking in which the seller does not get to know the exact watermarked copy that the buyer receives and the seller cannot create copies of the original content containing the buyers watermark. Expand
Counterfeiting attacks on oblivious block-wise independent invisible watermarking schemes
It is shown that oblivious watermarking techniques that embed information into a host image in a block-wise independent fashion are vulnerable to a counterfeiting attack. Expand
Authentication using graphical passwords: effects of tolerance and image choice
Results show that accurate memory for the password is strongly reduced when using a small tolerance around the user's password points, which suggests that many images may support memorability in graphical password systems. Expand
Spatio–Temporal Transform Based Video Hashing
It is found that these hash functions are resistant to signal processing and transmission impairments, and therefore can be instrumental in building database search, broadcast monitoring and watermarking applications for video. Expand
An efficient and robust method for detecting copy-move forgery
The proposed features can detect duplicated region in the images very accurately, even when the copied region was undergone severe image manipulations and use of counting bloom filters offers a considerable improvement in time efficiency at the expense of a slight reduction in the robustness. Expand
Steganalysis using image quality metrics
Simulation results with the chosen feature set and well-known watermarking and steganographic techniques indicate that the proposed approach is able with reasonable accuracy to distinguish between cover and stego images. Expand
CALIC-a context based adaptive lossless image codec
  • Xiaolin Wu, N. Memon
  • Computer Science
  • IEEE International Conference on Acoustics…
  • 7 May 1996
This work proposes a context-based, adaptive, lossless image codec (CALIC), which obtains higher lossless compression of continuous-tone images than other techniques reported in the literature and has relatively low time and space complexities. Expand
Secret and public key image watermarking schemes for image authentication and ownership verification
  • P. Wong, N. Memon
  • Computer Science, Medicine
  • IEEE Trans. Image Process.
  • 1 October 2001
A watermarking scheme for ownership verification and authentication that requires a user key during both the insertion and the extraction procedures, and which can detect any modification made to the image and indicate the specific locations that have been modified. Expand