Objective(s): In SPECT, the sinogram contains scatter and lack of attenuated counts that degrade the reconstructed image quality and quantity. Many techniques for attenuation and scatter correction have been proposed. An acceptable method of correction is to incorporate effects into an iterative statistical reconstruction. Here, we propose new Maximum Likelihood Expectation Maximiz...

Most of the wavelet threshold denoising methods need to calculate the corresponding threshold. The estimation of noise variance will directly affect the effect of threshold denoising method. This paper describes a new phase matching method of the noise variance estimation. The real-time noise can be estimated by this method. The experiments show that the method can greatly improve the signal to...

Introduction: One of the major problems in the development of nuclear medicine images is the presence of noise. The noise level in nuclear medicine images is usually reduced by the analysis of imaging data in a Fourier transform environment. The main drawback of this environment belongs to low signal to noise ratio in high frequencies because removing noise frequencies may remove data and times...

This paper includes different approaches for adaptive wavelet threshold (Bayes Shrink and Normal Shrink) and a robust wavelet domain method for noise filtering in ultrasound images. The search for efficient image denoising methods is still a valid challenge at the crossing of functional analysis and statistics. The proposed work in this paper extends the existing technique by improving the thre...

1. Biomedical Imaging Group, EPFL, CH-1015 Lausanne VD, Switzerland. 2. Escuela Politecnica Superior, Univ. San Pablo-CEU, Campus Urb. Monteprincipe s/n, 28668 Boadilla del Monte, Madrid, Spain. 3. Lab. d'analyse ultrastructurale, Univ. de Lausanne, CH-1015 Lausanne VD, Switzerland. 4. Howard Hughes Medical Institute, Molecular & cell biology Dept. Univ. of California, Berkeley, Ca 94720, USA. ...

A long-term aim of current research into the frequency assignment problem is to identify features that would enable us to classify instances of the problem in terms of certain easily-computed parameters. Although there are good mathematical reasons why this may be impossible in full generality, experimental evidence is emerging which suggests that instances which occur in practice may be amenab...

A method for estimating the signal-to-noise ratio from a single image is presented in this paper. The autocorrelation-based technique requires that image details be correlated over distances of a few pixels, while the noise is assumed to be uncorrelated from pixel to pixel. The latter is shown to be a good approximation in the case of scanning electron microscope (SEM) images provided that the ...

in RF receiving coil design. However, modern is proportional to 0 , so that their population imaging techniques often demand very high speed difference is larger at high values of 0 . Since the and spatial resolution, so that the highest possible ratio of the energy difference to thermal energy is SNR is still required to avoid poor image quality. very small, the population difference increases...

Introduction Signal intensity uniformity in a magnetic resonance (MR) image indicates how well the MR imaging (MRI) system represents an object. One of the major sources of image non-uniformity in high-field MRI scanners is inhomogeneity of radio-frequency coil. The aim of this study was to investigate non-uniformity in head, head and neck, and body coils and compare the obtained results to det...

Contrast detection is impaired in amblyopes. To understand the contrast processing deficit in amblyopia, we studied the effects of masking noise on contrast threshold in amblyopic macaque monkeys. Amblyopia developed as a result of either experimentally induced strabismus or anisometropia. We used random spatiotemporal broadband noise of varying contrast power to mask the detection of sinusoida...