Keh-Shih Chuang

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Measurement of image quality is very important for various applications such as image compression, restoration and enhancement. Conventional methods (e.g., mean squared error; MSE) use error summation to measure quality change pixel by pixel and do not correlate well with subjective quality measurement. This is due to the fact that human eyes extract(More)
Group independent component analysis (gICA) was performed on resting-state data from 14 healthy subjects scanned on 5 fMRI scan sessions across 16 days. The data were reduced and aggregated in 3 steps using Principal Components Analysis (PCA, within scan, within session and across session) and subjected to gICA procedures. The amount of reduction was(More)
An efficient method has been developed to speed up the computational time required for tissue separation after the dual-energy scan in computerized tomography and digital radiography. This method consists of two steps. First, an isotransmission line method is used to replace the iterative algorithm for solving the two nonlinear equations, which is(More)
To perform unilateral or bilateral upper thoracic ganglionectomy, we established a three-dimensional system of coordinates for T2 and T3 ganglia. For this purpose, the spatial relations were represented by drawings obtained from 50 Chinese cadavers. A simple stereotactic frame was constructed as an aid in performing the procedure. Then, according to the(More)
A postreconstruction method for correcting the beam-hardening artifacts in computed tomography (CT) images is proposed. This method does not require x-ray spectrum measurement. The authors assumed that a pixel in a CT image can be decomposed into equivalent tissue percentages, depending on its CT number. A scout view of the step wedges made of these(More)
Many studies have been performed on quality evaluation for subtle differences in medical images. However, only limited success has been achieved. In this paper, medical images were prior manipulated by denoising, lossy compression and filtering. The Moran statistics is then applied to extract spatial information of images and using Kolmogorov-Smirnov (KS)(More)
To present a pseudo lossless compression which modifies the noise component of the bit data to enhance the compression without affecting image quality? The hypothesis behind the study is that the bit data contaminated by noise can be manipulated without affecting image quality. The compression method comprises of three steps: (1) to estimate the noise level(More)
The three-dimensional (3D) object data obtained from a CT scanner usually have unequal sampling frequencies in the x-, y- and z-directions. Generally, the 3D data are first interpolated between slices to obtain isotropic resolution, reconstructed, then operated on using object extraction and display algorithms. The traditional grey-level interpolation(More)
The effects of stellate ganglionectomy on cardiovascular function were assessed in pentobarbital-anesthetized cats. A right stellectomy produced much more profound bradycardiac effects than a left stellectomy. This finding demonstrated that the stellate ganglion exerted a lateralized influence on heart beat in the cat. The cardiovascular response of intact(More)
Two methods are commonly used to visualize digital radiologic imaging data: (1) hard-copy viewing, in which the digital data are used to modulate the intensity of a laser beam that exposes an analog film and (2) soft-copy viewing, in which the digital data are converted to an analog video signal and presented on a CRT monitor. The film method allows new(More)