to investigate the effect of preprocessing techniques including contrast enhancement and illumination correction on retinal imagequality, a comparative study was carried out. we studied and implemented a few illumination correction and contrast enhancementtechniques on color retinal images to find out the best technique for optimum image enhancement. to compare and choose thebest illumination c...

With progress in radar systems, a number of methods have been developed for signal processing and detection in radars. A number of modern radar signal processing methods use time-frequency transforms, especially the wavelet transform (WT) which is a well-known linear transform. The interference canceling is one of the most important applications of the wavelet transform. In Ad-hoc detection met...

All-pass filters are useful devices that allow phase correction or equalization of signal without introducing any amplitude distortion. We present a new design scheme in which a grating is introduced in the interaction region of the two adjacent microrings in a cascaded multiring structure. The analysis accounts for the counter-directional coupling between the two waveguides. Theoretical analys...

* This work was supported in part by NATO under grant 0103/88. Dr. Kleihorst is currently with Philips Research Laboratories, Eindhoven, the Netherlands. ABSTRACT Even original video sequences are often corrupted by a certain amount of noise. As a result of the gammacorrection in camera's, the observation noise is signaldependent. In this paper we present a spatio-temporal order statistic (OS) ...

using a new numerical model, the pump-to-signal relative intensity noise (rin) transfer in singlepumpfiber optical parametric amplifiers for low modulation frequencies is investigated. the model includesfiber loss, pump depletion, as well as the gain saturation, and therefore, it can describe the practicalcircumstances associated with various applications of fiber optical parametric amplifiers....

Methods Rest and adenosine stress perfusion imaging was performed on 17 normal volunteers. A saturation recovery SSFP dual-sequence technique was used to acquire three myocardial slices and an arterial input function (AIF) image series. A proton-density weighted image was acquired at the beginning of each series. Fully quantitative perfusion pixel maps were generated by an automated processing ...

In this paper, a real-time denoising filter based on modelling of stable hybrid models is presented. Thehybrid models are composed of the shearlet filter and the adaptive Wiener filter in different forms.The optimization of various models is accomplished by the genetic algorithm. Next, regarding thesignificant relationship between Optimal models and input images, changing the structure of Optim...

In physical geodesy, the residual terrain modelling (RTM) technique is frequently used for highfrequency gravity forward modelling. In the RTM technique, a detailed elevation model is high-pass filtered in the topography domain, which is not equivalent to filtering in the gravity domain. This in-equivalence, denoted as spectral filter problem of the RTM technique, gives rise to two imperfection...

Spatio-temporal pattern formation in contra-directional two-wave mixing in photorefractive crystals is investigated both numerically and analytically, taking high-modulation-depth effects into account. We use a modified two-wavemixing model that includes a correction function f ðmÞ, which is introduced as a phenomenological modification. Transverse instabilities arise only if the modulation dep...

4.35k1.86 15.48f3.21 Abstract Previous research showed that whitening the surface electromyogram (EMC) can improve EMG amplitude estimation. However, conventional linear-filter whitening fails at low EMG amplitude levels, perhaps due to additive background noise in the measured EMG signal. This paper describes an adaptive whitening technique, effective at low EMG levels, that cascades a non-ada...