Enhancement of contrast and sharpness of an image is required in many applications. Unsharp masking is a classical tool for sharpness enhancement. We propose a generalized unsharp masking algorithm using the exploratory data model as a unified framework. The proposed algorithm is designed to address three issues: (1) simultaneously enhancing contrast and sharpness by means of individual treatment of the model component and the residual, (2) reducing the halo effect by means of an edge-preserving filter, and (3) solving the out-of-range problem by means of log-ratio and tangent operations. We also present a study of the properties of the log-ratio operations and reveal a new connection between the Bregman divergence and the generalized linear systems. This connection not only provides a novel insight into the geometrical property of such systems, but also opens a new pathway for system development. We present a new system called the tangent system which is based upon a specific Bregman divergence. Experimental results, which are comparable to recently published results, show that the proposed algorithm is able to significantly improve the contrast and sharpness of an image. In the proposed algorithm, the user can adjust the two parameters controlling the contrast and sharpness to produce the desired results. This makes the proposed algorithm practically useful.
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http://dx.doi.org/10.1109/TIP.2010.2092441 | DOI Listing |
Jpn J Radiol
January 2025
Department of Radiology, Ehime University Graduate School of Medicine, Shitsukawa, Toon, Ehime, 791-0295, Japan.
Purpose: To evaluate the effects of four-dimensional noise reduction filtering using a similarity algorithm (4D-SF) on the image quality and tumor visibility of low-dose dynamic computed tomography (CT) in evaluating breast cancer.
Materials And Methods: Thirty-four patients with 38 lesions who underwent low-dose dynamic breast CT and were pathologically diagnosed with breast cancer were enrolled. Dynamic CT images were reconstructed using iterative reconstruction alone or in combination with 4D-SF.
Clin Radiol
December 2024
Department of Radiology and Research Institute of Radiology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Republic of Korea.
Aim: To compare the image quality obtained using two accelerated high-resolution 3D fluid-attenuated inversion recovery (FLAIR) techniques for the brain-deep learning-reconstruction SPACE (DL-SPACE) and Wave-CAIPI FLAIR.
Materials And Methods: A total of 123 participants who underwent DL-SPACE and Wave-CAIPI FLAIR brain imaging were retrospectively reviewed. In a qualitative analysis, two radiologists rated the quality of each image, including the overall image quality, artifacts, sharpness, fine-structure conspicuity, and lesion conspicuity based on Likert scales.
AJNR Am J Neuroradiol
January 2025
From the Department of Radiology, Mayo Clinic, Jacksonville, FL, USA (Z.L., X.Z., S.T., V.P., E.M.W., V.G., E.H.M.), Department of Radiology, Peking Union Medical College Hospital, Beijing, China (Z.L.), Siemens Medical Solutions USA, Inc., Jacksonville, FL, USA (J.M.), MR Application Predevelopment, Siemens Healthineers AG, Forchheim, Germany (D.N., P.L.), Siemens Healthineers, Princeton, NJ, USA (M.M.), Siemens Medical Solutions USA, Inc., Scottsdale, AZ, USA (H.M.), and Department of Radiology, Mayo Clinic, Scottsdale, AZ, USA (H.M.).
Prolonged imaging times and motion sensitivity at 7T necessitate advancements in image acceleration techniques. This study evaluates a 7T deep-learning (DL)-based image reconstruction using a deep neural network trained on 7T data, applied to T2-weighted turbo spin echo imaging. Raw k-space data from 30 consecutive clinical 7T brain MRI patients was reconstructed using both DL and standard methods.
View Article and Find Full Text PDFMagn Reson Med
January 2025
Institute of Diagnostic and Interventional Radiology, Hannover Medical School, Hannover, Germany.
Purpose: Pulmonary MRI faces challenges due to low proton density, rapid transverse magnetization decay, and cardiac and respiratory motion. The fermat-looped orthogonally encoded trajectories (FLORET) sequence addresses these issues with high sampling efficiency, strong signal, and motion robustness, but has not yet been applied to phase-resolved functional lung (PREFUL) MRI-a contrast-free method for assessing pulmonary ventilation during free breathing. This study aims to develop a reconstruction pipeline for FLORET UTE, enhancing spatial resolution for three-dimensional (3D) PREFUL ventilation analysis.
View Article and Find Full Text PDFAcad Radiol
January 2025
Department of Radiology, University Hospital Tuebingen, Hoppe-Seyler-Str. 3, 72076 Tuebingen, Germany (R.D., J.M.B., B.S., J.M., S.G., P.K., S.W., J.H., K.N., S.A., A.B.).
Rationale And Objectives: Photon Counting CT (PCCT) offers advanced imaging capabilities with potential for substantial radiation dose reduction; however, achieving this without compromising image quality remains a challenge due to increased noise at lower doses. This study aims to evaluate the effectiveness of a deep learning (DL)-based denoising algorithm in maintaining diagnostic image quality in whole-body PCCT imaging at reduced radiation levels, using real intraindividual cadaveric scans.
Materials And Methods: Twenty-four cadaveric human bodies underwent whole-body CT scans on a PCCT scanner (NAEOTOM Alpha, Siemens Healthineers) at four different dose levels (100%, 50%, 25%, and 10% mAs).
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