A defocus blur metric for use in blind image quality assessment is proposed. Blind image deconvolution methods are used to determine the metric. Existing direct deconvolution methods based on the cepstrum, bicepstrum and on a spectral subtraction technique are compared across 210 images. A variation of the spectral subtraction method, based on a power spectrum surface of revolution, is proposed...

Far-field microphone speech signals cause high error rates for automatic speech recognition systems, due to room reverberation and lower signal-to-noise ratios. We have observed large increases in speech recognition word error rates when using a far-field (3-6 feet) microphone in a conference room, in comparison with recordings from close-talking microphones. In an earlier paper, we showed impr...

Most speech enhancement techniques do not perform very well in correlated or colored noise, as they assume that noise and speech are not correlated. In this paper, we propose a method, based on spectral subtraction, which takes into account possible correlation between noise and speech. Objective measures showed that the proposed method outperformed the power spectral subtraction method resulti...

The speech processing systems used to communicate or store speech are usually designed for a noise free environment. But the presence of background interference in the form of additive background and channel noise drastically degrades the performance of these systems, causing inaccurate information exchange and listener fatigue. To obtain a more intelligible speech signal, and one that is more ...

A subcarrier spectral amplitude coding optical code division multiple access system using the Khazani-Syed code with Complementary subtraction detection technique is proposed. The proposed system has been analyzed by taking into account the effects of phase-induced intensity noise, shot noise, thermal noise and intermodulation distortion noise. The performance of the system has been compared wi...

This paper proposes hands-free speech recognition using blind source separation (BSS) post-processed by two-stage spectral subtraction (2S-SS). The BSS using independent component analysis (ICA) estimates a target signal and jammer signals. The 2S-SS removes its residual crosstalk components and suppresses spatially-distributed noise not separated by BSS. In large vocabulary continuous speech r...

Far-field microphone speech signals cause high error rates for automatic speech recognition systems, due to room reverberation and lower signal-to-noise ratios. We have observed large increases in speech recognition word error rates when using a far-field (3-6 feet) microphone in a conference room, in comparison with recordings from close-talking microphones. In an earlier paper, we showed impr...

The demand for efficient optical communication systems has fuelled considerable research in developing techniques for eradicating phase-induced intensity noise (PIIN) in spectral-amplitude coding optical code-division multiple-access (SAC-OCDMA). This paper investigates the use of modified-AND subtraction detection technique to mitigate PIIN in SAC-OCDMA systems. The simulation results show tha...

We proposed a blind dereverberation method based on spectral subtraction byMulti-Channel Least Mean Square (MCLMS) algorithm for distant-talking speech recognition in our previous study [1]. In this paper, we discuss the problems of the proposed method and present some solutions. In a distant-talking environment, the length of channel impulse response is longer than the short-term spectral anal...

To reduce the effects of additive noises, spectral subtraction (SS) is often used. We discuss SS on the power spectral domain. This method has two problems to make the estimation of clean speech difficult:(1) There exists the estimation error between true power spectrum of noise and estimated one (2) The correlation between speech and noise also exists because of the phase difference. To overco...