Digital image is often degraded by many kinds of noise during the process of acquisition and transmission. To make subsequent processing more convenient, it is necessary to decrease the effect of noise. There are many kinds of noises in image, which mainly include salt and pepper noise and Gaussian noise. This paper focuses on median filters to remove the salt and pepper noise. After summarizin...

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...

Introduction: Using computed tomography (CT) is increasing significantly in Iran and worldwide. Reduction of CT's radiation dose is a critical concern. The aim of this study was evaluating the effect of localizer kVp on spiral CT images when the tube current modulation (TCM) is activated. Materials and Methods: A special wedding cake phantom with circular in...

The contourlet transform has the benefit of efficiently capturing the oriented geometrical structures of images. In this paper, by incorporating the ideas of Stein’s Unbiased Risk Estimator (SURE) approach in Nonsubsampled Contourlet Transform (NSCT) domain, a new image denoising technique is devised. We utilize the characteristics of NSCT coefficients in high and low subbands and apply SURE sh...

In this paper a new patch-based digital signature (DS) is proposed. The proposed approach similar to steganography methods hides the secure message in a host image. However, it uses a patch-based key to encode/decode the data like cryptography approaches. Both the host image and key patches are randomly initialized. The proposed approach consists of encoding and decoding algorithms. The encodin...

conclusion various filters are needed to improve the image quality. in this study, seven different filters were implemented and investigated on both noisy and noise-free images. background developmental dysplasia of the hip (ddh) can be detected with ultrasonography (usg) images. however, the accuracy of this method is dependent on the skill of the radiologist. radiologists measure the hip join...

periodic noises are unwished and spurious signals that create repetitive pattern on images and decreased the visual quality. firstly, this paper investigates various methods for reducing the effects of the periodic noise in digital images. then an adaptive optimum notch filter is proposed. in the proposed method, the regions of noise frequencies are determined by analyzing the spectral of noisy...

MRI is one of the most powerful techniques to study the internal structure of the body. MRI image quality is affected by various noises. Noises in MRI are usually thermal and mainly due to the motion of charged particles in the coil. Noise in MRI images also cause a limitation in the study of visual images as well as computer analysis of the images. In this paper, first, it is proved that proba...