1,721,080 research outputs found
A New Psychovisual Threshold Technique in Image Processing Applications
Get PDFA psychovisual threshold is developed based on the psychoacoustic quite threshold. Psychovisual threshold is obtained from quantitative experiments by evaluating the just noticeable difference (JND) at various frequency orders. Psychovisual threshold is suitable to be implemented in image compression and image watermarking applications. In image compression, the experimental results produced largely free artifacts in the visual output image and better image quality at the higher compression rate than JPEG image compression. This technique is suitable to be used in image watermarking, the experimental results indicated that the proposed scheme can achieve high imperceptibility and robustness
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Semi-fragile image watermarking using quantization-based DCT for tamper localization
Get PDFThis paper proposes a tamper detection technique for semi-fragile watermarking using Quantization-based Discrete Cosine Transform (DCT) for tamper localization. In this study, the proposed embedding strategy is investigated by experimental tests over the diagonal order of the DCT coefficients. The cover image is divided into non-overlapping blocks of size 8 × 8 pixels. The DCT is applied to each block, and the coefficients are arranged using a zig-zag pattern within the block. In this study, the low-frequency coefficients are selected to examine the impact of the imperceptibility score and tamper detection accuracy. High accuracy of tamper detection can be achieved by checking the surrounding blocks to determine whether the corresponding block has been tampered with. The proposed tamper detection is tested under various malicious, incidental, and hybrid attacks (both incidental and malicious attacks). The experimental results demonstrate that the proposed technique achieves a Peak-Signal-to-Noise Ratio (PSNR) value of 41.2318 dB, an average Structural Similarity Index Measure (SSIM) value of 0.9768. The proposed scheme is also evaluated against malicious attacks such as copy-move, object deletion, object manipulation, and collage attacks. The proposed scheme can detect the malicious attack localization under various tampering rates. In addition, the proposed scheme can still detect tampered pixels under a hybrid attack, such as a combination of malicious and incidental attacks, with an average accuracy of 96.44%
Multiple watermarking technique using optimal threshold
Get PDFThe multiple watermarking technique has drawn more attention due to high demand for embedding more than one copyright. This paper proposes a multiple watermarking scheme using DWT-SVD by utilizing HVS characteristics. Our scheme embeds multiple watermarks in red and blue colors. The proposed scheme examines the coefficients of U orthogonal matrix for embedding and extracting watermarks. Watermarks are scrambled by Arnold transform before embedded in the host image in order provide additional security. The optimal thresholds for red and blue colors are revealed by finding a trade-off between normalized-cross correlation and imperceptibility from quantization steps. The experimental results demonstrate that our scheme achieves high resistant under JPEG and JPEG2000 compression for both inserted watermarks
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
An improved hiding information by modifying selected DWT coefficients in video steganography
Get PDFThe rapid expansion of information technology enables users to transfer data or files via the internet in a short time. Steganography is the art of embedding secret information or messages in multimedia data. Video is the most popular medium in steganography to transmit data from sender to receiver. Video has a larger hiding capacity and it provides large redundancy space in video frame sequences. The objective of this research is to embed into the selected video frames based on a new hiding technique with the discrete wavelet transform (DWT). The selected video frames based on scene change detection were chosen for hiding data to minimise the visibility effect on the stego-video. DWT was computed to decompose the selected video frame into sub-bands, the approximation coefficient matrix of two-level DWT was selected to embed the data. The proposed scheme was compared to the existing schemes in terms of imperceptibility. The experimental results showed that the proposed technique achieved high SSIM and PSNR values. The proposed scheme achieved an SSIM value of 0.990 and a PSNR value of 46.09 dB. In addition, the proposed steganography scheme produced good robustness against MPEG-4 compression whereby the message can be fully recognized
Tchebichef image watermarking along the edge using YCoCg-R color space for copyright protection
Get PDFEasy creation and manipulation of digital images present the potential danger of counterfeiting and forgery. Watermarking technique which embeds a watermark into the images can be used to overcome these problems and to provide copyright protection. Digital image watermarking should meet requirements, e.g. maintain image quality, difficult to remove the watermark, quality of watermark extraction, and applicable. This research proposes Tchebichef watermarking along the edge based on YCoCg-R color space. The embedding region is selected by considering the human visual characteristics (HVC) entropy. The selected blocks with minimum of HVC entropy values are transformed by Tchebichef moments. The locations of C(0,1), C(1,0), C(0,2) and C(2,0) of the matrix moment are randomly embedded for each watermark bit. The proposed watermarking scheme produces a good imperceptibility by average SSIM value around 0.98. The watermark recovery has greater resistant after several types of attack than other schemes. © 2019 Institute of Advanced Engineering and Science. All rights reserved
An efficient adaptive scaling factor for 4×4 DCT image watermarking
Get PDFThe imperceptibility and robustness properties of the watermarked image are the major requirements for maintaining the watermarked image similar to the original image and keeping the inserted watermark resistant under various attacks. In order to optimize the scaling factor for balancing between imperceptibility and robustness, this paper proposed a technique to generate scaling factors by considering the image content. The scaling factor is generated based on selected DCT coefficients of 4 × 4 DCT. The proposed watermarking can generate dynamic scaling factors for different DCT coefficients. The embedding regions are determined by using variance pixels, whereby the highest variance pixel was prioritised for the first embedding watermark. The watermark image pixels were scrambled by using an Arnold cat map before the watermark was embedded. This research uses 10 images from USC-SIPI image database to evaluate the effectiveness of the proposed watermarking. The experimental results showed that the proposed method improved the invisibility of the watermarked image with PSNR value of 45.38 dB rather than other watermarking schemes. The proposed watermarking showed superior performance against different types of attack
Adaptive scaling factors based on the impact of selected DCT coefficients for image watermarking
Get PDFImage watermarking technique aims at high imperceptibility of the embedded watermark with minimal distortion in the watermarked images. In frequency-domain, block-based Discrete Cosine Transform (DCT) is a popular method which can be improved by different scaling factors. This paper presents an adaptive scaling factor for selected DCT coefficients in image watermarking. The image blocks that have lowest pixel variances are chosen as the embedding locations. The optimal scaling factors for selected DCT coefficients on the middle frequencies are obtained by finding the best quality of images. The embedding process is performed using the obtained scaling factors. The proposed technique was investigated to verify the robustness and imperceptibility against various image-processing attacks. It is proved that our technique achieves higher robustness against noise addition, filter and compression than the existing schemes in most cases. Our technique produces greater imperceptibility than the existing schemes
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