Khaly Tall

Adaptive steganography scheme based on LDPC codes

Steganography is the art of secret communication. Since the advent of modern steganography, in the 2000s, many approaches based on the error correcting codes (Hamming, BCH, RS, STC ...) have been proposed to reduce the number of changes of the cover medium while inserting the maximum bits. The works of LDiop and al [1], inspired by those of T. Filler [2] have shown that the LDPC codes are good candidates in minimizing the impact of insertion. This work is a continuation of the use of LDPC codes in steganography. We propose in this paper a steganography scheme based on these codes inspired by the adaptive approach to the calculation of the map detectability. We evaluated the performance of our method by applying an algorithm for steganalysis.

Soft output detection for MIMO systems using binary polar codes

Polar codes are proven capacity-achieving and are shown to have equivalent or even better finite length performance than turbo/LDPC codes under some improved decoding algorithm over the Additive White Gaussian Noise (AWGN) channels. Polar coding is based on the so-called channel polarization phenomenon induced by a transform over the underlying binary-input channel. The channel polarization is found to be universal in many signal processing problems and is applied to the coded modulation schemes. In this paper, a small length polar, encoded for a MIMO (Multiple-Input Multiple-Output) systems with soft output MMSE-SIC (Minimum Mean Square Error-Successive Cancellation) detection, is applied to improve the coded performance while reducing the complexity. In order to prove this theory, we compare the proposed MMSE-SIC BER to Zero Forcing (ZF) and Maximum Likelihood (ML) by using 2*2 MIMO systems into Rayleigh channel with BPSK (Binary Phase-Shift Keying) modulation. Simulation results show that MMSE-SIC complexity is lower than the two others detections. We show that the performance of the proposed approach using polar code (128, 64) at 10−2 BER (Bit Error Rate) is around 3dB i.e. 0,66% compared to the optimal ML, while ZF performance is the worst.

Study of polar codes MIMO channels polarization using MIMO system

Polar codes are known as the first provable code construction to achieve Shannon capacity for arbitrary symmetric binary input channels. Several schemes to provides both detection/decoding of the transmitted and the transmit antenna index in Multiple-Input Multiple-Output (MIMO) antenna systems were proposed in the literature for polar codes. In this paper we have critically analyzed various MIMO channel polarization using polar codes extended to the multiple antenna transmission, and also have covered free polar set and frozen polar set for respectively mapping transmitted information and transmit antenna index.

Adaptive linear programming of polar codes to minimize additive distortion in steganography

A new practical syndrome coding method is proposed in this paper to minimize a suitably defined additive distortion function using Adaptive Linear Programming of Polar Codes (ALP-PC). We propose modifications of the ALP-PC based on a new reduced factor graph for steganographic purposes which we denote by ALP-PCS. The implementation of wet paper codes in practice is possible using ALP-PCS. Simulation results show that this method minimizes additive distortion in steganography and gives good embedding efficiency performance.

Small Polar Codes Concatenating to STBC Applied to MIMO Systems

This paper uses a concatenation of small Polar Codes length (N=32) and Space Time Block Code, this Polar-STBC is applied to no diversity (SISO), SIMO, MISO and MIMO systems. Minimum Mean Square Error using Successive Interference Cancellation (MMSE-SIC) is a soft output used to the receiver in order to improve Bit Error Rate (BER) and finally Successive Cancellation Decoder (SCD) is placed to the decoder in order to improve the BER and Frame Error Rate (FER). Comparison between several STBC without concatenation schemes and this small Polar-STBC shown that the proposed allows minimizing the BER and FER performances.

Increase MIMO Systems Performances by Concatenating Short Polar Codes to Spatial Time Block Codes

Polar codes, proposed by Erdal Arikan, have attracted a lot of interest in the field of channel coding for their capacity-achieving trait as well as their low encoding and decoding complexity in order O (NlogN) under successive cancellation (SC) decoder. However, there remains one significant drawback, that is, the error correction performance of short and moderate length polar codes is unsatisfactory, especially when compared with low-density parity check (LDPC) codes and turbo codes. In this paper, we propose a concatenation scheme performance, which employs a short polar encoder following to Spatial Time Block Codes (STBC), and we develop an efficient detector for Multiple Input Multiple Output (MIMO) antennas, which adaptively combines Minimum Mean Square Error Successive Interference Canceller together (MMSE-SIC). We also compared to Maximum Likelihood in the literature and finally present a simulation results in binary input Additive White Gaussian Noise (BI-AWGN) with binary phase shift keying (BPSK) modulation, and we observe that, our proposed concatenation scheme significantly outperforms the Maximum Likelihood performance in the high Signal-to-Noise-Ratio (SNR).

Polar Coding Steganographic Embedding Using Successive Cancellation

In this paper, we propose a practical adaptive embedding methodology based on Successive Cancellation (SC) polar coding. The new proposed SC-based Polar Coding Steganography (SC-PCS) defines message bits as frozen bits of the SC decoder and computes path metrics according to embedding costs of pixels of the cover image. Simulation results demonstrate that SC-PCS minimizes an arbitrary embedding distortion while embedding covert message.

Classification Model of Spikes Morphology Using Principal Components Analysis in Drug-Resistant Epilepsy

Epilepsy is one of the diseases that are more subject to consultation in neurological clinics. To help neurologists to accurately diagnose this disease, several technological tools have been developed. Electroencephalography (EEG) of scalp or deep is a signal acquisition tool from electrical discharges of the brain areas. These signals are often accompanied by transient events commonly called interictal paroxystic events (IPE) or spikes of short durations. Analysis of these IPE could help with the diagnosis of drug-resistant epilepsy. With this intention, we will first of all seek to detect IPE, by separating them from the basic activity of signal EEG. In this paper, we propose spike detection method based on Smoothed Nonlinear Energy Operator (SNEO) using adaptive threshold. Then we will implement a new approach using principal components analysis (PCA) before classification to separate the events detected according to their morphologies. The objective in the long term is to characterize their space-time distribution over all the duration of the EEG signal.

JPEG2000 compression for scintigraphic images of metastasis of the prostatic cancer

A remote DICOM (Digital Imaging Communication in Medicine) server needs an important storage and a high-speed network of, at least, 100 Mbps. This is a limitation for the storage and for remote access to images and image processing softwares. Objective: We set up, in this study, a secondary server that saves medical images of prostatic cancer patients compressed by JPEG 2000, the new standard of image compression. This first study has to set up an intranet and a remote server. Method: We compress to JPEG2000 the images picked up in PNG and Bitmap formats from the DICOM server using the scientific software MATLAB. Results: JPEG 2000 compression save the contrast of bone scintigraphic images. For the lossless compression the results are, respectively, 1.66 and 9.86 for the PNG format and Bitmap format. The lossy compression gives a compression ratio of, respectively, 6.48 and 40.3 for the two formats. The minimum and maximum for images compressed in PNG are 2.0 and 10.5 corresponding to a Peak Signal-to-Noise Ratio (PSNR) of, respectively, 62.9 dB and 37.8 dB. That lossy compression reduces all the images at the weight of 58 Kibi-octet (Kio). Conclusion: These compression ratios work with a good interpretation of the whole body bone scintigraphic images we used. That is proved by the visual metric as well as the PSNR. It also permits the image transmission through a low speed network. This makes easy the access on patient data in the hospital and eventually from a remote location.

Performances of the estimation and motion compensation for the reconstruction of motion areas in a sequence video Motion JPEG 2000

In a very noisy environment, the transmission of video sequences Motion JPEG 2000 is not entirely reliable since attending packet loss in the codestream the movie Motion JPEG 2000. For a reconstruction of the lost packets, the method of conditional replenishment has been proposed. However, with this method, the effects of blocks appear in motion areas making the quality of the video poor in these areas. In this paper, we propose the method of estimation and motion compensation for optimal recovery of lost packets in motion areas. Thus, the application implementation in Matlab can see firsthand the disappearance of the effects of blocks in the transmission of video sequence Motion JPEG 2000 in a very noisy environment.