Review on Watermarking Techniques Aiming Authentication of Digital Image Artistic Works Minted as NFTs into Blockchains

The recent creation of Non Fungible Tokens (NFTs) has enabled a multibillionaire market for digital artistic works including images or sequence of images, videos, and animated gifs. With this new trend issues regarding fraud, stolen works, authenticity, and copyright came along. The goal of this chapter is to provide an overview of the watermarking techniques that can be employed to mitigate those issues. We will discuss transparency, robustness, and payload of watermarking techniques aiming to educate the artists, researchers, and developers about the many approaches that watermarking techniques provide and the resulting trade-offs. We focus on fragile watermarking techniques due to their high transparency for embedding into artistic works. We discuss the spread spectrum and Least Significant Bit techniques. We describe the usual process of NFT minting into a blockchain and propose a more secure certification protocol with watermarking which employs the same usual NFT minting offered by current marketplaces. The proposed certification protocol mints a checksum string into a blockchain, ensuring the validity of the watermark and the information embedded into this watermark. This proposed protocol validates the date of creation and author identification which are transparently embedded in the artistic work, thus, increasing the security and confidence of markets for artistic works transactions

SIMULTANEOUS SUPER-RESOLUTION FOR VIDEO SEQUENCES

In this work, we propose a new super-resolution algorithm to simultaneously estimate all frames of a video sequence. The new algorithm is based on the Bayesian maximum a posteriori estimation. In contrast to other multi-frame super-resolution algorithms, the proposed algorithm does not include the motion in the observation model. Instead, transformations caused by the motion are used as a prior information in order to achieve smoothness in the motion trajectory. The proposed algorithm provides lower computational complexity than the traditional super-resolution algorithms when several frames need to be restored. The new algorithm is also robust to motion errors and outliers. We provide results to illustrate the superiority of the new method. 1

Data Hiding for Printed Binary Documents Robust to Print-Scan, Photocopy and Geometric Attacks

Abstract — This paper presents a data hiding technique for printed bicolor documents. It inserts tiny dots, hardly noticeable at normal reading distance, to embed the message. For message extraction, we employ auto-correlation and tiny registration dots to rectify geometric distortions. This technique is robust to distortions resulting from print-scan operations, good quality photocopies, affine transformations and scribblings/stains on the paper. The technique can be applied to documents with large white (or black) areas and they may present characters, drawings, schematics, diagrams, cartoons, but not halftones. The technique is intended to be neither a robust watermark (because any filtering can remove the dots) nor a covert communication (because the dots are perceptible at short distance). Nevertheless, when combined with a perceptual hashing and a cryptography protocol, it can be applied as semi-fragile authentication watermarking for hardcopy two-tone documents. In some situations, the utilization of the proposed system can substitute the use of notarial authenticated photocopies. Index Terms — Data hiding, semi-fragile watermarking, geometric attacks, print-scan and photocopy robustness