A. Tawfik

A novel blind image watermarking technique for colour RGB images in the DCT domain using green channel

This paper presents a new algorithm for colour digital image watermarking. The 24 bits/pixel RGB images are used and the watermark is placed on the green channel of the RGB image. The green channel is chosen after an analytical investigation process was carried out using some popular measurement metrics. The analysis and embedding processes have been carried out using the discrete cosine transform DCT. The new watermarking method has shown to be resistant to JPEG compression, cropping, scaling, low-pass, median and removal attack. This algorithm produces more than 65 dB of average PSNR.

Mapping 3-D IIR digital filter onto systolic arrays

We present here an efficient systolic implementation for 3-D IIR digital filters. The systolic implementation is obtained by using an algebraic mapping technique. This new mapping technique gives us the choice to mix pipelined variables and broadcast variables. We also determine, through the mapping method, the buffer sizes, the direction of variables propagations and the data feeding and extracting points. The resultant systolic array implementation is a modular structure composed of 2-D filter modules connected by simple buffers. This new systolic implementation is regular, modular and amenable to VLSI Implementation.

A New Blind Image Watermarking Technique for Dual Watermarks Using Low-Frequency Band DCT Coefficients

This paper deals with a new blind robust watermarking technique for embedding two watermarks into a host image. The technique is based on embedding watermark information in sixteen low-frequency band coefficients of the DCT sub-blocks. The embedding process is based on changing the selected DCT-coefficients of the host image to odd or even values depending on the binary watermarks bit value. The proposed blind watermarking embedding has shown to be strongly robust against several attacks.

A New Blind Image Watermarking of Handwritten Signatures using Low-Frequency Band DCT Coefficients

This paper deals with a new blind technique for robust image watermarking in the DCT domain. The technique is based on embedding watermark information in eight low-frequency band coefficients of the DCT sub-blocks. Single watermark has been embedded multi-times in the host image. The embedding process is based on changing the selected DCT-coefficients of the host image to odd or even values depending on the binary watermarks bit value. The proposed blind watermarking embedding has shown to be strongly robust against several attacks.

High-speed area-efficient inner-product processor

In this paper, a novel technique for the design of a high-speed word-level twos complement fixed-point inner-product processor is described. The new scheme offers a highly regular structure ideally suited for VLSI implementation. A comparison in terms of speed and area between the proposed scheme and two other inner-product processors is presented. A reduction in the computation time ranging from 20% to 50% compared with other schemes has been achieved using the proposed processor, without a significant increase in the required area.

A modified dithered signed-error constant-modulus algorithm for blind adaptive equalizer

Adaptive blind equalization has gained widespread use in communication receivers that operate without training signals. In particular, the constant modulus algorithm (CMA) has become a favourite of practitioners due to its LMS-like complexity and desirable robustness properties. The desire for further reduction in computational complexity has motivated signed-error versions of CMA (SE-CMA) which have been found to lack the robustness properties of CMA. Alternatively a dithered signed-error of CMA (DSE-CMA) based on the judicious use of dither, has been proposed which results in algorithm with robustness properties nearly identical to those of CMA with the cost of the degradation in steady-state mean square error (MSE) performance. This paper presents a modified dithered signed-error version of CMA (MDSE-CMA) which is motivated by a reduction of the steady-state MSE of DSE-CMA without increase in its computational complexity.

A new inner-product processor for FIR filter implementation

A new fixed-point inner-product processor is presented to be used in an FIR array processor implementation. The processor enhances the speed of operation with a slight increase in area. Moreover, the new processor would improve the noise performance of the system since a double-precision word is assigned for the output without incurring extra communication overhead.

Systolic implementation of linear-phase FIR filters

A systematic method is used for mapping linear-phase FIR filter algorithms onto systolic hardware. The method is based on the z-domain characterization of the required filter and yields filter structures that are modular and pipelined. A special processor module is presented which performs an add-multiply-accumulate operation in the same time as a simple multiplier.<<ETX>>

A frequency domain adaptive watermarking algorithm for still colour images

This paper presents an adaptive algorithm for digital watermarking of still colour images. The watermark is embedded in the DCT coefficients of the green channel of the RGB colour image. The algorithm takes into account the perceptual capacity of each coefficient inside the DCT blocks before embedding the watermark information. Therefore, the first 16 low frequency coefficients (excluding the DC value) in the 8×8 DCT block was screened and the eight coefficients with the maximum magnitudes were selected for embedding. The algorithm used is blind and does not require the original image for extracting the watermark. The peak signal to noise ratios (PSNR) is around 60dB. The watermarking method is shown to be robust against JPEG compression, additive noise, cropping, scaling, low-pass and median filtering.

Efficient systolic implementation of fixed-point state-space digital filter

We present an efficient systolic implementation for N-order state-space IIR digital filters. The proposed systolic architecture provides an excellent performance in terms of area and speed. A comparison between the suggested systolic architecture and two other conventional architectures is also presented.<<ETX>>