OBJECTIVE Dynamic positron emission tomography (PET), which reveals information about both the spatial distribution and temporal kinetics of a radiotracer, enables quantitative interpretation of PET data. Model-based interpretation of dynamic PET images by means of parametric fitting, however, is often a challenging task due to high levels of noise, thus necessitating a denoising step. The obje...

In this work we comment the results presented in [1] regarding a random sampling approach of the Non Local Means (NLM) image denoising filter with respect to computational cost and denoising performance. We will show that although the approach is novel and mathematically revealing, the computation cost of the approach is higher, and the PSNR lower, compared to the classical version. Furthermore...

Image resolution in 4D-CT is a crucial bottleneck that needs to be overcome for improved dose planning in radiotherapy for lung cancer. In this paper, we propose a novel patch-based algorithm to enhance the image quality of 4D-CT data. Our premise is that anatomical information missing in one phase can be recovered from complementary information embedded in other phases. We employ a patch-based...

In this paper, a novel improvement idea in image restoration by Non-Local means (NL-means) filter is proposed. Most of special image denoising techniques require a region size called neighborhood window for denoising, window-size selection is usually done by visual inspection based upon experience or hit and trial. It is shown in this paper that varying the window-size for each pixel according ...

In this paper we study the impact of denoising the raw high angular resolution diffusion imaging (HARDI) data with the Non-Local Means filter adapted to Rician noise (NLMr). We first show that NLMr filtering improves robustness of apparent diffusion coefficient (ADC) and orientation distribution function (ODF) reconstructions from synthetic HARDI datasets. Our results suggest that the NLMr filt...

Introduction: Myocardial T2* measurement is a valuable tool for non-invasive assessment of tissue iron overload which can prevent disease in thalassemia patients (1). For the heavily iron loaded heart, T2* is substantially shortened (<10ms) and the signal to noise ratios (SNRs) of later echo images are usually very low (2). Various signal processing techniques have been proposed for denoising M...

A new Collaborative Approach for eNhanced Denoising under Low-light Excitation (CANDLE) is introduced for the processing of 3D laser scanning multiphoton microscopy images. CANDLE is designed to be robust for low signal-to-noise ratio (SNR) conditions typically encountered when imaging deep in scattering biological specimens. Based on an optimized non-local means filter involving the comparison...

Removing as much noise possible in an image while preserving its fine details is a complex and challenging task. We propose wavelet-based non-local means (NLM) denoising method to overcome the problem. Two well-known wavelets: dual-tree wavelet transform (DT-CWT) discrete (DWT), have been used change into several coefficients sequentially. NLM filtering universal hard thresholding with cycle sp...