QR Code Approach for Examination Process

Using the QR codes is one of the most intriguing ways of digitally connecting consumers to the internet via mobile phones since the mobile phones have become a basic necessity thing of everyone The detection of QR codes, a type of 2D barcode, as described in the literature consists merely in the determination of the boundaries of the symbol region in images obtained with the specific intent of highlighting the symbol .In order to improve the practical application property of the two-dimensional barcode Quick Response (QR) code, we investigate the coding and decoding process of the QR code image. The barcode is a real mechanism for data reads. Data can be stored, embedded and through the scanning device to show. The store of data which being read. In this paper, we present a methodology for creating QR code approach for virtual word examination process by using different techniques like SHA256, encoding, decoding, and Error correction. DOI: 10.17762/ijritcc2321-8169.15024

DWT-Based Watermarking Using QR Code

Increased commercial activity on the Internet and media industries demandsprotection of multimedia contents. In this paper, we introduce a novel watermarkingmethod to embed QR codes in digital images. The method is based on discrete wavelettransform (DWT). The original image is divided into blocks, and QR codes are added toparticular bits of LL2 level coefficients of the selected block according to the visual maskingeffect of the human visual system. It has been shown that this method is robust for JPEGcompression and has good transparency. The embedded information can be extractedcorrectly even if the images are compressed to 11% of the original according to the contentsof the images

Fragile Watermarking using Chaotic Sequences *

Abstract I

Implementation and performance study of image data hiding/watermarking schemes

Two data hiding / watermarking techniques for grayscale and color images are presented. One of them is DCT based, another uses DFT to embed data. Both methods were implemented in software utilizing C/C++. The complete listings of these programs are included. A comprehensive reliability analysis was performed on both schemes, subjecting watermarked images to JPEG, SPIRT and MPEG-2 compressions. In addition, the pictures were examined by exposing them to common signal processing operations such as image resizing, rotation, histogram equalization and stretching, random, uniform and Gaussian noise addition, brightness and contrast variations, gamma correction, image sharpening and softening, edge enhancement, manipulation of a channel bit number and others. Methods were compared to each other. It has been shown that the DCT method is more robust and, hence, suitable for watermarking purposes. The DFT scheme exhibits less robustness, but due to its higher capacity is perfect for data hiding purposes

Robust watermarking of point-sampled geometry

We present a new scheme for digital watermarking of point-sampled geometry based on spectral analysis. By extending existing algorithms designed for polygonal data to unstructured point clouds, our method is particularly suited for scanned models, where the watermark can be directly embedded in the raw data obtained from the 3D acquisition device. To handle large data sets efficiently, we apply a fast hierarchical clustering algorithm that partitions the model into a set of patches. Each patch is mapped into the space of eigenfunctions of an approximate Laplacian operator to obtain a decomposition of the patch surface into discrete frequency bands. The watermark is then embedded into the low frequency components to minimize visual artifacts in the model geometry. During extraction, the target model is resampled at optimal resolution using an MLS projection. After extracting a watermark from this model, the corresponding bit stream is analyzed using statistical methods based on correlation. We have applied our method to a number of point-sampled models of different geometric and topological complexity. These experiments show that our watermarking scheme is robust against numerous attacks, including low-pass filtering, resampling, affine transformations, cropping, additive random noise, and combinations of the above

Adaptive and perceptual watermarking of still images

This paper presents a new adaptive and perceptual watermarking algorithm. This algorithm is called perceptual as it uses a model of the human visual system (HVS) to determine the auspicious sites for watermarking. The HVS modelisation considered here is consistent with a decomposition that uses a non directional low pass channel and a set of three band pass radial frequency channels each being decomposed into angular sectors. The watermarking is also called adaptive as it exploits an error visibility model to compute for each image and for each selected site the maximum watermark strength to be applied without inducing visible degradations. The algorithm performances have been evaluated in terms of watermark invisibility and robustness to different attacks. In the first case, subjective tests, based on CCIR recommandation, have been conducted to assess visual quality of images watermarked with different strengths. In the second case, the correlation coefficient is used to determine the original watermark detection efficiency to attacks such as filtering, noise addition, JPEG compression, pseudo-cropping and limited geométric distorsions.Cet article présente un nouvel algorithme de tatouage perceptuel et adaptatif. Il est perceptuel parce qu'il exploite une modélisation du comportement du système visuel humain pour déterminer les sites propices au tatouage. La modélisation considérée ici, décompose l'espace de représentation en 17 canaux visuels. Ces derniers se répartissent en un canal basses fréquences non directionnel et trois bandes de fréquences radiales, elles mêmes décomposées en canaux angulaires dont le nombre dépend de la bande radiale considérée. Le tatouage est dit également adaptatif parce qu'il utilise un modèle de perception des erreurs pour calculer la force maximale à appliquer pour que l'intégration du filigrane n'engendre pas de dégradations visibles. Les performances de cette approche ont été évaluées en termes de transparence du filigrane et de sa robustesse à différentes attaques. Dans le premier cas, des tests d'évaluation menés selon la recommandation 500 du CCIR ont permis de juger en fonction de la force du filigrane, la qualité visuelle des images tatouées par rapport à celle des images originales. Dans le deuxième cas, le calcul du coefficient de corrélation a permis d'analyser l'efficacité du recouvrement du filigrane original face à des attaques comme le filtrage passe-bas, le filtrage median, l'ajout de bruit, la compression JPEG à différents taux, le pseudo-cropping et les attaques géométriques limitées

Integration and optimization of collusion secure fingerprinting in image watermarking

Estágio realizado na Fraunhofer SIT - e orientado pelo Dr. Huajian Liu e pelo Dr. Marcel SchäferTese de mestrado integrado. Engenharia Electrotécnica e de Computadores. Faculdade de Engenharia. Universidade do Porto. 201