Nematollah Zarmehi

Nematollah Zarmehi
Sharif University of Technology | SHARIF · Department of Electrical Engineering

Ph.D.

About

20
Publications
2,579
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64
Citations

Publications

Publications (20)
Article
In this paper, we propose a new method to reconstruct a signal corrupted by noise where both signal and noise are sparse but in different domains. The main contribution of our algorithm is its low complexity; the run-time is much lower than most other algorithms. The reconstruction quality of our algorithm both objectively (in terms of PSNR and SSI...
Article
The matrix decomposing into a sum of low-rank and sparse components has found extensive applications in many areas including video surveillance, computer vision, and medical imaging. In this paper, we propose a new algorithm for recovery of low rank and sparse components of a given matrix. We have also proved the convergence of the proposed algorit...
Article
In this paper, we propose two methods for signal denoising where both signal and noise are sparse but in different domains. First, an optimization problem is proposed which is non-convex and NP-hard due to the existence of ℓ0 norm in its cost function. Then, we propose two approaches to approximate and solve it. We also provide the proof of converg...
Article
In this paper, we propose an algorithm for recovery of sparse and low-rank components of matrices using an iterative method with adaptive thresholding. In each iteration of the algorithm, the low-rank and sparse components are obtained using a thresholding operator. The proposed algorithm is fast and can be implemented easily. We compare it with th...
Article
This paper proposes some bounds on the maximum of magnitude of a random mask in Fourier domain. The random mask is used in random sampling scheme. Having a bound on the maximum value of a random mask in Fourier domain is very useful for some iterative recovery methods that use thresholding operator. In this paper, we propose some different bounds a...
Article
This paper proposes a robust watermarking method for uncompressed video data against H.264/AVC and H.265/HEVC compression standards. We embed the watermark data in the mid-range transform coefficients of a block that is less similar to its corresponding block in the previous and next frames. This idea makes the watermark robust against the compress...
Conference Paper
This paper proposes some bounds on maximum magnitude of a random mask in Fourier domain. The random mask is used in random sampling scheme. Having a bound on the maximum value of a random mask in Fourier domain is very useful for some iterative recovery methods that use thresholding operator. In this paper, we propose some different bounds and comp...
Article
In this paper, we propose an Adaptive Singular Value Thresholding (ASVT) for low rank recovery under affine constraints. Unlike previous iterative methods that the threshold level is independent of the iteration number, in our proposed method the threshold in adaptively decreases during iterations. The simulation results reveal that we get better p...
Article
In this paper, we will provide a comparison between uniform and random sampling for speech and music signals. There are various sampling and recovery methods for audio signals. Here, we only investigate uniform and random schemes for sampling and basic low-pass filtering and iterative method with adaptive thresholding for recovery. The simulation r...
Article
In this letter, we propose an algorithm for recovery of sparse and low rank components of matrices using an iterative method with adaptive thresholding. In each iteration, the low rank and sparse components are obtained using a thresholding operator. This algorithm is fast and can be implemented easily. We compare it with one of the most common fas...
Article
This paper investigates the multiplicative spread spectrum watermarking method for the image. The information bit is spreaded into middle-frequency Discrete Cosine Transform (DCT) coeffcients of each block of an image using a generated pseudo-random sequence. Unlike the conventional signal modeling, we suppose that both signal and noise are distrib...
Article
In this study, the authors propose a steganalytic scheme for digital video spread spectrum (SS) data hiding. The proposed method estimates both the hidden message and the gain factor of the SS embedding rules. In this method, the cover frames are first estimated and are compared with the received video frames. Then, the residual matrix is computed...
Conference Paper
In this paper we propose a video steganalysis method toward multiplicative spread spectrum embedding. We use the redundancies of the video frames to estimate the cover frame and after extracting some features from the video frames and the estimated ones, the received video is classified as suspicious or not suspicious. In the case that the video de...
Thesis
Nowadays, security is a very necessary aspect of communications, even more important than communication itself. Cryptography is a method of providing security in which the sender and receiver exchange the message between themselves by an alphabet which is meaningless to the third party. On the other hand, steganography adds two security layers to s...
Conference Paper
Full-text available
In this paper, we investigate an additive video watermarking method in H.264 standard in presence of the Laplacian noise. In some applications, due to the loss of some pixels or a region of a frame, we resort to Laplacian noise rather than Gaussian one. The embedding is performed in the transform domain; while an optimum and a sub-optimum decoder a...
Thesis
همزمان با پيشرفت روز افزون ارتباطات الکترونيکي، مسائلي از قبيل تشخيص هويت، جلوگيري از کپي و تکثير غيرمجاز رسانه هاي ديجيتال، امنيت ارسال داده و ... بيشتر از قبل مورد توجه قرار گرفته اند. به عنوان مثال از دغددغه هاي اصلي توليدکنندگان محصولات رسانه ديجيتال، جلوگيري از کپي و تکثير غير مجاز محصولاتشان است. بسياري از افراد به دليل فراگير و ارزان بودن شب...

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