نتایج جستجو برای: image uniformity

تعداد نتایج: 389857  

2003
Ping Tan Stephen Lin Long Quan Harry Shum

We present a single-image highlight removal method that incorporates illumination-based constraints into image inpainting. Unlike occluded image regions filled by traditional inpainting, highlight pixels contain some useful information for guiding the inpainting process. Constraints provided by observed pixel colors, highlight color analysis and illumination color uniformity are employed in our...

Journal: :journal of medical signals and sensors 0
mohamad amin bakhshali mousa shamsi

background: nowadays, analyzing human facial image has gained ever-increasing importance due to its various applications. image segmentation is required as a very important and fundamental operation for significant analysis and interpretation of images. methods: among the segmentation methods, image thresholding technique is one of the most well-known methods due to its simplicity, robustness a...

2016
Weiling Hu Xu Zhang Bin Wang Jiquan Liu Huilong Duan Ning Dai Jianmin Si

Image registration is a key component of computer assistance in image guided surgery, and it is a challenging topic in endoscopic environments. In this study, we present a method for image registration named Homographic Patch Feature Transform (HPFT) to match gastroscopic images. HPFT can be used for tracking lesions and augmenting reality applications during gastroscopy. Furthermore, an overal...

2007
Eric K. Zeise Don Williams Peter D. Burns William C. Kress

Inexpensive and easy-to-use linear and area-array scanners have frequently substituted as colorimeters and densitometers for low-frequency (i.e., large area) hard copy image measurement. Increasingly, scanners are also being used for high spatial frequency, image microstructure measurements, which were previously reserved for high performance microdensitometers. In this paper we address charact...

Journal: :Medical physics 2008
N Mail D J Moseley J H Siewerdsen D A Jaffray

Image lag degrades image quality in cone-beam CT (CBCT), resulting in contrast reduction, lack of CT number accuracy and uniformity, and skin-line artifacts. The magnitude of such degradation and the extent to which imaging performance can be improved by means of a lag correction method were investigated. Measurements were performed using a radiotherapy CBCT guidance system (Elekta Synergy XVI,...

Journal: :Int. J. Imaging Systems and Technology 2005
Alfred M. Bruckstein Robert J. Holt Arun N. Netravali

Self-similar progressive image sampling schemes that have been recently proposed for holographic image representations are shown to generate two-dimensional low discrepancy sequences. The discrepancy of a planar set of points is a measure of the uniformity of their placement in the plane. Sequences, or planar sets of points with low discrepancy, cover the image domain as uniformly as possible. ...

1999
Du-Sik Park Jong Seung Park Tae-Yong Kim Joon Hee Han

Image indexing is the process of image retrieval from databases of images or videos based on their contents. Specifically, histogram-based algorithms are considered to be effective for color image indexing. We suggest a new method of color space quantization in the CIELUV color space, named weighted LUV quantization. With this method, each bin in the LUV space has a different weighting factor, ...

Journal: :Journal of nuclear medicine : official publication, Society of Nuclear Medicine 2014
Jeffrey S Nelson Olav I Christianson Beth A Harkness Mark T Madsen Eugene Mah Stephen R Thomas Habib Zaidi Ehsan Samei

UNLABELLED Because γ cameras are generally susceptible to environmental conditions and system vulnerabilities, they require routine evaluation of uniformity performance. The metrics for such evaluations are commonly pixel value-based. Although these metrics are typically successful at identifying regional nonuniformities, they often do not adequately reflect subtle periodic structures; therefor...

Alireza Kamali Asl Hamid Jafari Majid Shahreyari Seyed Mahdi Safavi,

Introduction: Radiation imaging is one of the applicable methods in diagnostic medicine and nondestructive testing for industrial applications. In nondestructive 3D imaging, in addition to the radiation source, there is a requirement for a suitable detection system, data acquisition system, mechanical sections for moving objects, reconstruction algorithm and finally a computer for processing an...

2012
Olivier Gayou

The production of high quality pretreatment images plays an increasing role in image-guided radiotherapy (IGRT) and adaptive radiation therapy (ART). Megavoltage cone-beam computed tomography (MV-CBCT) is the simplest solution of all the commercially available volumetric imaging systems for localization. It also suffers the most from relatively poor contrast due to the energy range of the imagi...

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