Davide Cavagnino

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In this paper, a block-based watermarking scheme based on the Singular Value Decomposition (SVD) is proposed. Our watermark, a pseudo-random Gaussian sequence, is embedded by modifying the angles formed by the right singular vectors of each block of the original image. The orthogonality property of the right singular vector matrix is preserved during the(More)
Automatic recognition of complex images is a hard and computationally expensive task, mainly because it is extremely difficult to capture in an automatic way and with a few features the necessary discriminant information. If such features were available, a proper learning system could be trained to distinguish images of different kinds of objects, starting(More)
This paper presents a method that allows for securely saving a temporal sequence of data (log lines) in a file. Log lines are signed by an authority, and are thus unalterable without detection. Data is also encrypted in the file, and may be accessed with the granularity of a single log line with the possession of a decryption key. Also, it is possible that(More)
Fragile watermarking has attracted a lot of attention in the last decade. An interesting approach, presented in 2011 by Lin et al., results in very high quality of the watermarked images. However, after a thorough examination of the paper, a few improvements are proposed in our revised version of the algorithm in order to overcome some shortcomings. In(More)