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Author

J. N. Ellinas

Other affiliations: Athens State University
Bio: J. N. Ellinas is an academic researcher from National and Kapodistrian University of Athens. The author has contributed to research in topics: Digital watermarking & Discrete wavelet transform. The author has an hindex of 8, co-authored 13 publications receiving 145 citations. Previous affiliations of J. N. Ellinas include Athens State University.

Papers
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Journal ArticleDOI
TL;DR: A new stereo image compression scheme that is based on the wavelet transform of both images and the disparity estimation between the stereo pair subbands and demonstrates very good performance as far as PSNR measures and visual quality are concerned and low complexity.

49 citations

Journal ArticleDOI
10 Oct 2005
TL;DR: In this paper, an improved interpolated motion and disparity estimation (EIMDE) method was proposed to encode the frames of the right image sequence by exploiting both the temporal redundancy of the same sequence and the disparity redundancy with the left image sequence.
Abstract: A new optimised technique for coding stereoscopic image sequences is presented and compared with already known methods. The proposed technique, called enhanced interpolated motion and disparity estimation (EIMDE), is based on the joint method, which encodes the frames of the right image sequence by exploiting both the temporal redundancy of the same sequence and the disparity redundancy with the left image sequence. In the proposed method, a variable block size scheme has been employed for motion and disparity estimation. The block size is controlled by quad-tree decomposition of the processed frame based on a rate-distortion splitting criterion. For the prediction of a macroblock, optimised motion and disparity vectors are jointly estimated and the participating proportion of each similarity is suitably searched. In this way, the energy of the resulted residual frame is minimised and the whole framework is optimised. Finally, the residual frame is decomposed by a discrete wavelet transform and is further compressed by morphological encoding the resulting coefficients. The proposed coder has been experimentally evaluated on real image sequences, where it produced good performance over other known methods.

20 citations

Journal Article
TL;DR: An approach for still image digital watermarking in which the watermark embedding process employs the wavelet transform and incorporates Human Visual System (HVS) characteristics.
Abstract: The efficiency of an image watermarking technique depends on the preservation of visually significant information. This is attained by embedding the watermark transparently with the maximum possible strength. The current paper presents an approach for still image digital watermarking in which the watermark embedding process employs the wavelet transform and incorporates Human Visual System (HVS) characteristics. The sensitivity of a human observer to contrast with respect to spatial frequency is described by the Contrast Sensitivity Function (CSF). The strength of the watermark within the decomposition subbands, which occupy an interval on the spatial frequencies, is adjusted according to this sensitivity. Moreover, the watermark embedding process is carried over the subband coefficients that lie on edges where distortions are less noticeable. The experimental evaluation of the proposed method shows very good results in terms of robustness and transparency.

16 citations

Journal ArticleDOI
TL;DR: A family of novel stereoscopic image coders based on morphological coding and a block-based disparity compensation algorithm that provides reconstructed images without blocking artifacts and fewer annoying ringing effects is proposed.

15 citations

Journal Article
TL;DR: A new reversible watermarking method is presented that reduces the size of a stereoscopic image sequence while keeping its content visible and hides a number of bits in intensity smooth areas and most of the data in textured areas where resulting distortions are less visible.
Abstract: In this paper, a new reversible watermarking method is presented that reduces the size of a stereoscopic image sequence while keeping its content visible The proposed technique embeds the residuals of the right frames to the corresponding frames of the left sequence, halving the total capacity The residual frames may result in after a disparity compensated procedure between the two video streams or by a joint motion and disparity compensation The residuals are usually lossy compressed before embedding because of the limited embedding capacity of the left frames The watermarked frames are visible at a high quality and at any instant the stereoscopic video may be recovered by an inverse process In fact, the left frames may be exactly recovered whereas the right ones are slightly distorted as the residuals are not embedded intact The employed embedding method reorders the left frame into an array of consecutive pixel pairs and embeds a number of bits according to their intensity difference In this way, it hides a number of bits in intensity smooth areas and most of the data in textured areas where resulting distortions are less visible The experimental evaluation demonstrates that the proposed scheme is quite effective Keywords—Stereoscopic video, Reversible watermarking, Disparity compensation, Joint compensation

13 citations


Cited by
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Journal ArticleDOI
TL;DR: This paper presents a review of the digital video watermarking techniques in which their applications, challenges, and important properties are discussed, and categorizes them based on the domain in which they embed the watermark.
Abstract: The illegal distribution of a digital movie is a common and significant threat to the film industry. With the advent of high-speed broadband Internet access, a pirated copy of a digital video can now be easily distributed to a global audience. A possible means of limiting this type of digital theft is digital video watermarking whereby additional information, called a watermark, is embedded in the host video. This watermark can be extracted at the decoder and used to determine whether the video content is watermarked. This paper presents a review of the digital video watermarking techniques in which their applications, challenges, and important properties are discussed, and categorizes them based on the domain in which they embed the watermark. It then provides an overview of a few emerging innovative solutions using watermarks. Protecting a 3D video by watermarking is an emerging area of research. The relevant 3D video watermarking techniques in the literature are classified based on the image-based representations of a 3D video in stereoscopic, depth-image-based rendering, and multi-view video watermarking. We discuss each technique, and then present a survey of the literature. Finally, we provide a summary of this paper and propose some future research directions.

181 citations

Journal ArticleDOI
TL;DR: A full reference metric for quality assessment of stereoscopic images based on the binocular fusion process characterizing the 3D human perception is proposed and the difference of binocular energy has shown a high correlation with the human judgement for different impairments and is used to build the Binocular Energy Quality Metric (BEQM).
Abstract: Stereoscopic imaging is becoming very popular and its deployment by means of photography, television, cinema. . .is rapidly increasing. Obviously, the access to this type of images imposes the use of compression and transmission that may generate artifacts of different natures. Consequently, it is important to have appropriate tools to measure the quality of stereoscopic content. Several studies tried to extend well-known metrics, such as the PSNR or SSIM, to 3D. However, the results are not as good as for 2D images and it becomes important to have metrics dealing with 3D perception. In this work, we propose a full reference metric for quality assessment of stereoscopic images based on the binocular fusion process characterizing the 3D human perception. The main idea consists of the development of a model allowing to reproduce the binocular signal generated by simple and complex cells, and to estimate the associated binocular energy. The difference of binocular energy has shown a high correlation with the human judgement for different impairments and is used to build the Binocular Energy Quality Metric (BEQM). Extensive experiments demonstrated the performance of the BEQM with regards to literature.

131 citations

Journal ArticleDOI
TL;DR: Experimental results show that the proposed GDWM outperforms other watermarking methods and is robust to a wide range of attacks, e.g., Gaussian filtering, amplitude scaling, median filtering, sharpening, JPEG compression, Gaussian noise, salt & pepper noise, and scaling.
Abstract: We propose a robust quantization-based image watermarking scheme, called the gradient direction watermarking (GDWM), based on the uniform quantization of the direction of gradient vectors. In GDWM, the watermark bits are embedded by quantizing the angles of significant gradient vectors at multiple wavelet scales. The proposed scheme has the following advantages: 1) increased invisibility of the embedded watermark because the watermark is embedded in significant gradient vectors, 2) robustness to amplitude scaling attacks because the watermark is embedded in the angles of the gradient vectors, and 3) increased watermarking capacity as the scheme uses multiple-scale embedding. The gradient vector at a pixel is expressed in terms of the discrete wavelet transform (DWT) coefficients. To quantize the gradient direction, the DWT coefficients are modified based on the derived relationship between the changes in the coefficients and the change in the gradient direction. Experimental results show that the proposed GDWM outperforms other watermarking methods and is robust to a wide range of attacks, e.g., Gaussian filtering, amplitude scaling, median filtering, sharpening, JPEG compression, Gaussian noise, salt & pepper noise, and scaling.

123 citations

Journal ArticleDOI
TL;DR: INSLR, a system that integrates various image processing techniques and computational intelligence techniques in order to deal with sentence recognition, is developed to improve communication between hearing impaired people and normal people promising them better social prospects.
Abstract: (INSLR) that integrates various image processing techniques and computational intelligence techniques in order to deal with sentence recognition. The system is developed to improve communication between hearing impaired people and normal people promising them better social prospects. A wavelet based video segmentation technique is proposed which detects shapes of various hand signs and head movement in video based setup. Shape features of hand gestures are extracted using elliptical Fourier descriptions which to the highest degree reduces the feature vectors for an image. Principle component analysis (PCA) still minimizes the feature vector for a particular gesture video and the features are not affected by scaling or rotation of gestures within a video which makes the system more flexible. Features generated using these techniques makes the feature vector unique for a particular gesture. Recognition of gestures from the extracted features is done using a Sugeno type fuzzy inference system which uses linear output membership functions. Finally the INSLR system employs an audio system to play the recognized gestures along with text output. The system is tested using a data set of 80 words and sentences by 10 different signers. The experimental results show that our system has a recognition rate of 96%.

61 citations

Patent
06 Dec 2013
TL;DR: In this paper, a method of coding multi-layer video data is proposed, which includes determining, for a first block of video data at a first temporal location, whether one or more reference picture lists for coding the first block contain at least one reference picture at a second, different temporal location.
Abstract: In an example, a method of coding multi-layer video data includes determining, for a first block of video data at a first temporal location, whether one or more reference picture lists for coding the first block contain at least one reference picture at a second, different temporal location. The method also includes coding the first block of video data relative to at least one reference block of video data of a reference picture in the one or more reference picture lists, where coding includes disabling an inter-view residual prediction process when the one or more reference picture lists do not include at least one reference picture at the second temporal location.

47 citations