A novel method for100Gbpsall-optical OFDM using Discrete Cosine Transform in a Radio-Over-Fiber link is proposed. The system is designed simply using both symmetric and asymmetric passive optical couplers. DCT is achieved all-optically by adjusting the length and splitting ratio of the couplers. The performance of the system is compared with all-optical OFDM based on Discrete Fourier, Discrete ...

A novel oblivious and highly robust watermarking scheme using Multiple Descriptions (MD) and Quantization Index Modulation (QIM) of the host image is presented in this paper. The watermark is embedded in the Discrete Contourlet Transform domain (CT). Discrete Countourlet Transform (CT) is able to capture the directional edges and contours superior to Discrete Wavelet Transform (DWT). Watermark ...

In modern communication technologies, the demand of image data compression increasing rapidly. This paper presents different methods for image compression like DCT, Walsh, Hadamard and Walsh Hadamard. Main objective of this paper is to achieve the higher compression ratio and lower the Mean square error. Different test images over different orthogonal transform are used to achieve the performan...

The images usually bring different kinds of noise in the process of receiving, coding and transmission. In this paper the Curvelet transform is used for de-noising of image. Two digital implementations of the Curvelet transform (a multiscale transform) viz the Unequally Spaced Fast Fourier Transform (USFFT) and the Wrapping Algorithm are used to de-noise images degraded by different types of no...

An example of application of the wavelet transform to electrocardiography is described in the paper. The transform is exploited as a first stage of an ECG signal compression algorithm. The signal is decomposed into particular time-frequency components. Some of the components are removed because of their low influence to signal shape due to nonstationary character of ECG. Resulted components are...

A discrete auditory transform (DAT) from sound signal to spectrum is presented and shown to be invertible in closed form. The transform preserves energy, and its spectrum is smoother than that of the discrete Fourier transform (DFT) consistent with human audition. DAT and DFT are compared in signal denoising tests with spectral thresholding method. The signals are noisy speech segments. It is f...

It is known that in an OFDM system using Hadamard transform or phase alteration before the IDFT operation can reduce the Peak-to-Average Power Ratio (PAPR). Both these techniques can be viewed as constellation precoding for PAPR reduction. In general, using non-diagonal transforms, like Hadamard transform, increases the ML decoding complexity. In this paper we propose the use of block-IDFT matr...

As to the hybrid noise characteristic, a mixed de-noising method is hereby proposed in combination with the median filter and the wavelet transform. Firstly, conduct the median filter to the pending image; then apply an improved threshold function to the wavelet transform (WT) to eliminate noise; finally, adopt Signal Noise Ratio (SNR) to evaluate the image de-noising effect. The experiment res...

This paper proposes novel lossy image compression technique using hybrid wavelet transform and vector quantization. First hybrid wavelet transform consisting of two different component transforms is generated and applied on color images. Discrete Kekre transform (DKT) and Discrete Cosine transform (DCT) play role of base and local transform respectively in hybrid wavelet transform. In transform...

—A concept for variable block-size transform coding is presented. It is called adaptive block-size transforms (ABT) and was proposed for coding of high resolution and interlaced video in the emerging video coding standard H.264/AVC. The basic idea of inter ABT is to align the block size used for transform coding of the prediction error to the block size used for motion compensation. Intra ABT e...