Hadamard transform

About: Hadamard transform is a research topic. Over the lifetime, 7262 publications have been published within this topic receiving 94328 citations.

Topographic feature extraction using sensor array system

Abstract: A method and apparatus for topographic feature extraction by masking a video signal representation of an optical image using a two-dimension Walsh function is disclosed. The optical energy of an image is converted into a video signal. A Walsh function signal in accordance with a two-dimension Walsh is generated. The video signal is multiplied with the Walsh function signal to produce a Walsh transform coefficients signal indicative of the decomposed spectral components of the image. The method and apparatus can further include providing selected topographical feature signals in accordance with the Walsh transform coefficients of selected topographic features. A selected topographical feature can be detected by comparing the Walsh transform coefficients signal with the selected topographical feature signals. The Walsh transform coefficients signal is unique to the selected topographical feature being detected.

Method and system for digital watermarking of multimedia signals

Abstract: Disclosed is a method and system for digital watermarking of multimedia signals. The input multimedia signal is represented using an inverse difference pyramid decomposition. Spectrum coefficients may be calculated for each level of the pyramid using a new kind of complex Hadamard transform, the matrix of which is distinguished from the known ones by the fact that only one-fourth of its coefficients are complex numbers. The phases of a previously selected part of the low-frequency coefficients are modified with the watermark data, limiting the angles of the phase changes in a gap of several degrees only. After an inverse complex Hadamard Transform, the values of the coefficients from all pyramid levels are summed up and the result is the watermarked signal. The watermark can contain multiple independent levels for each level of the pyramid.

Analytic Continuation by the Fast Fourier Transform

Abstract: The ill-posed problem of analytic continuation is regularized by a prescribed bound. A simple computer algorithm is given that is based on the fast Fourier transform. The algorithm computes m complex values and a positive error bound with time complexity $O(m\log m)$. As a function of the data errors and the prescribed bound, the numerical error is shown to be consistent with that prescribed by the three-circles principle of Hadamard.

Red-cyan anaglyph image watermarking using DWT, Hadamard transform and singular value decomposition for copyright protection

Abstract: This paper proposes a unique Red-Cyan Anaglyph image watermarking using DWT, Fast Walsh Hadamard transform and SVD. Watermarking of this particular image is not done extensively so far. Thus, this study focuses on the watermarking of red-cyan anaglyph image for copyright protection. With the help of DWT, Hadamard transform and SVD, the system tries to extract a robust feature to embed the watermark. The watermarking is carried out as. The cover image is transformed using Discrete Wavelet Transform and the watermark image of size 32 × 32 is scrambled using Arnold transform and it is hidden into the hadamard transformed blocks of the Anaglyph image exploiting singular values obtained by applying Singular Value Decomposition. The performance of this proposed system is checked for its robust nature and its imperceptibility on Middlebury Stereo database against usual image processing attacks such as Gaussian noise, filtering, etc. From the simulation results, it is clearly known that it has achieved better outcomes in terms of robustness and imperceptibility than the former existing papers.