Rogelio Reyes-Reyes

Image Authentication Scheme Based on Self-embedding Watermarking

This paper presents a block-wise and content-based semi-fragile image watermarking authentication scheme with location and recovery capability. Firstly the image is segmented by two regions: Region of Interest (ROI) and Region of Embedding (ROE). The watermark sequence is extracted from ROI and it is embedded into the middle frequency band of DCT coefficients of ROE. In the authentication stage, two watermark sequences extracted ROI and ROE, respectively, are used. If difference between both sequences of a ROI block is smaller than the predefined threshold value, the ROI block is determined authentic, otherwise the block is considered as tampered and it is recovered by the recovery process. The proposed scheme is evaluated from several points of view: watermark imperceptibility, capability of tamper detection, image quality of recovered regions and robustness of no-intentional manipulations, such as JPEG compression. The simulation results show fairly good performance of the proposed scheme.

Visible Watermarking Technique Based on Human Visual System for Single Sensor Digital Cameras

In this paper we propose a visible watermarking algorithm, in which a visible watermark is embedded into the Bayer Colour Filter Array (CFA) domain. The Bayer CFA is the most common raw image representation for images captured by single sensor digital cameras equipped in almost all mobile devices. In proposed scheme, the captured image is watermarked before it is compressed and stored in the storage system. Then this method enforces the rightful ownership of the watermarked image, since there is no other version of the image rather than the watermarked one. We also take into consideration the Human Visual System (HVS) so that the proposed technique provides desired characteristics of a visible watermarking scheme, such that the embedded watermark is sufficiently perceptible and at same time not obtrusive in colour and grey-scale images. Unlike other Bayer CFA domain visible watermarking algorithms, in which only binary watermark pattern is supported, proposed watermarking algorithm allows grey-scale and colour images as watermark patterns. It is suitable for advertisement purpose, such as digital library and e-commerce, besides copyright protection.

Satellite image Super-Resolution using overlapping blocks via sparse representation

In image processing the Super-Resolution (SR) has played an important role by acquiring High-Resolution (HR) images from the corresponding Low-Resolution (LR) images. In this paper, a Super-Resolution technique for satellite images is proposed but it can be used on images of different nature. In the current proposal to achieve a HR image, it is necessary an intermediate step, which consists in performing an initial interpolation, then features are extracted from this initial image, here, it is necessary to reduce the information obtained by the features extraction via principal component analysis (PCA). Patches are extracted from the initial image and the reduction via PCA. For each patch, the sparse representation is obtained and then, it is used to recover the HR image. By using the quality objective criteria PSNR and SSIM, the proposed technique is evaluated and shows a superiority in comparison against other existing proposals.

Visible watermarking technique in compressed domain based on JND

A distortion on an image can be invisible by the Human Visual System (HVS), if the distortion is under a threshold called Just Noticeable Distortion (JND), which is determined by several sensibility factors of the HVS, such as luminance and frequency sensibility. Until now, the JND is widely used for invisible watermarking schemes; however, in visible watermarking schemes this concept is not explored sufficiently. In this paper, a novel compressed domain visible watermarking method based on the JND profile is presented. The JND is estimated by texture and intensity of each 8×8 block of the Discrete Cosine Transform (DCT). Considering that the JPEG is the most widely used digital image format and almost all photographs captured by digital camera are stored in this format; the visible watermarking scheme in compressed domain without inverse DCT operation to obtain spatial image provides important advantage from security and complexity points of view.

Adaptive removable visible watermarking technique using dual watermarking for digital color images

This paper proposes a removable visible watermarking system based on a dual watermark technique and blind removal. A visible watermark pattern is embedded in the cosine discrete transform (DCT) domain, taking into consideration the texture and luminance features of the watermark and host images to create a visible watermarked image. To prevent illegal visible watermark removal, the original watermark is embedded in an invisible manner in the visible watermarked image by employing the Quantization Index Modulation-Dither Modulation (QIM-DM) technique, thus ensuring that the original watermark cannot be obtained by malicious attacks. The visible watermark removal process is carried out using only the correct user’s keys, without the need for additional information, such as the original watermark or the original host image, which allows a high-quality image to be obtained; however, if the user’s keys used in the removal process are wrong, the visible watermarked image suffers higher distortion in its content, even in non-visible watermarked regions. The experimental results show that the proposed system outperforms previous related works in terms of blind removal, preservation of the quality of the unmarked recovered image, and higher visual degradation of the content in the recovered image if an illegal removal attempt is performed.

Image super-resolution via two coupled dictionaries and sparse representation

In image processing, the super-resolution (SR) technique has played an important role to perform high-resolution (HR) images from the acquired low-resolution (LR) images. In this paper, a novel technique is proposed that can generate a SR image from a single LR input image. Designed framework can be used in images of different kinds. To reconstruct a HR image, it is necessary to perform an intermediate step, which consists of an initial interpolation; next, the features are extracted from this initial image via convolution operation. Then, the principal component analysis (PCA) is used to reduce information redundancy after features extraction step. Non-overlapping blocks are extracted, and for each block, the sparse representation is performed, which it is later used to recover the HR image. Using the quality objective criteria and subjective visual perception, the proposed technique has been evaluated demonstrating their competitive performance in comparison with state-of-the-art methods.

LSB-steganography framework for stereoscopic images based on BJND

Nowadays, stereoscopic images are commonly used for 3D image generation, these are composed by a pair of images viewed independently by each eye, which creates a feeling of immersion and in depth perception. 3D vision technologies have multiple applications in many different areas such as medicine, entertainment, computer vision, etc.; being accessible to a wider group of people. However, there is so few researches that seek to hide information in this type of 3D content. This paper proposes a new method to hide information into stereoscopic images using a LSB-Steganography technique and a Binocular Just Noticeable Difference model (BJND) embedding the maximum payload capacity avoiding visual artifacts and inaccurate 3D generation. Results demonstrate that it is possible to embed up to 1.87 Mb into the stereoscopic images keeping high imperceptibility, obtaining average values for PSNR and SSIM between the original stereoscopic pair and the modified of 31.12dB and 0.9693, respectively. Quantity Bad Pixels (QBP, δd= 0. 5) and SSIM are calculated for evaluating accurate 3D generation, obtaining average values of 41.26% and of 0.7721 between the ground-truth and the disparity map of the modified stereoscopic pair.

Parallel steganography framework for hiding a color image inside stereo images

In this work, a robust steganography framework to hide a color image into a stereo images is proposed. The embedding algorithm is performed via Discrete Cosine Transform (DCT) and Quantization Index Modulation-Dither Modulation (QIM-DM) hiding the secret data. Additionally, the Arnold’s Cat Map Transform is applied in order to scramble the secret color image, guaranteeing better security and robustness of the proposed system. Novel framework has demonstrated better performance against JPEG compression attacks among other existing approaches. Besides, the proposed algorithm is developed taking into account the parallel paradigm in order to be implemented in multi-core CPU increasing the processing speed. The results obtained by the proposed framework show high values of PSNR and SSIM, which demonstrate imperceptibility and sufficient robustness against JPEG compression attacks.

Parallel halftoning technique using dot diffusion optimization

In this paper, a novel approach for halftone images is proposed and implemented for images that are obtained by the Dot Diffusion (DD) method. Designed technique is based on an optimization of the so-called class matrix used in DD algorithm and it consists of generation new versions of class matrix, which has no baron and near-baron in order to minimize inconsistencies during the distribution of the error. Proposed class matrix has different properties and each is designed for two different applications: applications where the inverse-halftoning is necessary, and applications where this method is not required. The proposed method has been implemented in GPU (NVIDIA GeForce GTX 750 Ti), multicore processors (AMD FX(tm)-6300 Six-Core Processor and in Intel core i5-4200U), using CUDA and OpenCV over a PC with linux. Experimental results have shown that novel framework generates a good quality of the halftone images and the inverse halftone images obtained. The simulation results using parallel architectures have demonstrated the efficiency of the novel technique when it is implemented in real-time processing.

An automatic visible watermark detection method using total variation

Visible watermarking has been an important research area, widely studied and used for copyright protection over the years. However, new visible watermark removal-oriented attacks and techniques have emerged. Although these methods provide high quality resultant images, the main part of the attack consists of manual detection of the watermark pattern. Considering that visible watermark pattern can be different in each watermarked image, time-consuming human intervention is required, making these attacks inefficient in practice. In this paper, we propose an automatic detection method of visible watermark pattern, which can combine with conventional watermark removal attacks to make them more efficient. To accomplish it, the visible watermarked image is decomposed into structure image and texture image using Total Variation L1 (TV-L1) method. In the structure image, the watermark edge is discriminated from the edges present in the host image to automatically detect the visible watermark pattern.