scholarly journals Diameter, width, closest line pair, and parametric searching

1993 ◽  
Vol 10 (2) ◽  
pp. 183-196 ◽  
Author(s):  
Bernard Chazelle ◽  
Herbert Edelsbrunner ◽  
Leonidas Guibas ◽  
Micha Sharir
Keyword(s):  
Line Pair ◽  
Parametric Searching

P20 phosphor on polyimide as a large area high-resolution transmission screen for slow scan CCD systems

1995 ◽  
Vol 53 ◽  
pp. 20-21
Author(s):  
C. C. Ahn ◽  
S. Karnes ◽  
M. Lvovsky ◽  
C. M. Garland ◽  
H. A. Atwater ◽  
...  
Keyword(s):  
Mechanical Stability ◽  
High Energy ◽  
Practical Implementation ◽  
Line Pair ◽  
Modulation Transfer ◽  
Large Area ◽  
Ccd Imaging ◽  
Transmission Electron ◽  
The One ◽  
Beam Broadening

The bane of CCD imaging systems for transmission electron microscopy at intermediate and high voltages has been their relatively poor modulation transfer function (MTF), or line pair resolution. The problem originates primarily with the phosphor screen. On the one hand, screens should be thick so that as many incident electrons as possible are converted to photons, yielding a high detective quantum efficiency(DQE). The MTF diminishes as a function of scintillator thickness however, and to some extent as a function of fluorescence within the scintillator substrates. Fan has noted that the use of a thin layer of phosphor beneath a self supporting 2μ, thick Al substrate might provide the most appropriate compromise for high DQE and MTF in transmission electron microcscopes which operate at higher voltages. Monte Carlo simulations of high energy electron trajectories reveal that only little beam broadening occurs within this thickness of Al film. Consequently, the MTF is limited predominantly by broadening within the thin phosphor underlayer. There are difficulties however, in the practical implementation of this design, associated mostly with the mechanical stability of the Al support film.

scholarly journals Hidden by bias: how standard psychophysical procedures conceal crucial aspects of peripheral visual appearance

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Fazilet Zeynep Yildirim ◽  
Daniel R. Coates ◽  
Bilge Sayim
Keyword(s):  
Visual Perception ◽  
Line Pair ◽  
Crucial Aspect ◽  
Time And Space ◽  
Contextual Modulation ◽  
Visual Appearance ◽  
Single Time ◽  
Visual Periphery ◽  
Contextual Stimuli ◽  
Biased Perception

AbstractThe perception of a target depends on other stimuli surrounding it in time and space. This contextual modulation is ubiquitous in visual perception, and is usually quantified by measuring performance on sets of highly similar stimuli. Implicit or explicit comparisons among the stimuli may, however, inadvertently bias responses and conceal strong variability of target appearance. Here, we investigated the influence of contextual stimuli on the perception of a repeating pattern (a line triplet), presented in the visual periphery. In the neutral condition, the triplet was presented a single time to capture its minimally biased perception. In the similar and dissimilar conditions, it was presented within stimulus sets composed of lines similar to the triplet, and distinct shapes, respectively. The majority of observers reported perceiving a line pair in the neutral and dissimilar conditions, revealing ‘redundancy masking’, the reduction of the perceived number of repeating items. In the similar condition, by contrast, the number of lines was overestimated. Our results show that the similar context did not reveal redundancy masking which was only observed in the neutral and dissimilar context. We suggest that the influence of contextual stimuli has inadvertently concealed this crucial aspect of peripheral appearance.

scholarly journals Braille Block Detection via Multi-Objective Optimization from an Egocentric Viewpoint

Sensors ◽  
2021 ◽  
Vol 21 (8) ◽  
pp. 2775
Author(s):  
Tsubasa Takano ◽  
Takumi Nakane ◽  
Takuya Akashi ◽  
Chao Zhang
Keyword(s):  
Optimization Problem ◽  
Line Pair ◽  
Objective Functions ◽  
Multi Objective Optimization ◽  
Multi Objective ◽  
Optimization Framework ◽  
Visually Impaired People ◽  
Comprehensive Comparison ◽  
Basic Characteristics ◽  
Support Devices

In this paper, we propose a method to detect Braille blocks from an egocentric viewpoint, which is a key part of many walking support devices for visually impaired people. Our main contribution is to cast this task as a multi-objective optimization problem and exploits both the geometric and the appearance features for detection. Specifically, two objective functions were designed under an evolutionary optimization framework with a line pair modeled as an individual (i.e., solution). Both of the objectives follow the basic characteristics of the Braille blocks, which aim to clarify the boundaries and estimate the likelihood of the Braille block surface. Our proposed method was assessed by an originally collected and annotated dataset under real scenarios. Both quantitative and qualitative experimental results show that the proposed method can detect Braille blocks under various environments. We also provide a comprehensive comparison of the detection performance with respect to different multi-objective optimization algorithms.

scholarly journals Correlation between spatial resolution and ball distortion rate of panoramic radiography

2020 ◽  
Author(s):  
Han-Gyeol Yeom ◽  
Sam-Sun Lee ◽  
Jo-Eun Kim ◽  
Kyung-Hoe Huh ◽  
Won-Jin Yi ◽  
...  
Keyword(s):  
Standard Deviation ◽  
Spatial Resolution ◽  
Panoramic Radiography ◽  
Reference Value ◽  
Vertical Line ◽  
Line Pair ◽  
Horizontal Line ◽  
Student’S T ◽  
High Degree ◽  
Distortion Rate

Abstract BackgroundThe purpose of this study was to analyze the correlation between spatial resolution and ball distortion rate of panoramic radiography and to elucidate the minimum criterion for ball distortion rate, which is very relevant to clinical readability.MethodsHorizontal and vertical spatial resolution and ball distortion rates were calculated in the same position, such as the incisor, premolar, molar, and temporomandibular joint area with various object depths corresponding to 48 mm. Three devices were evaluated. A region showing spatial resolution above the reference standard was selected, and the ball distortion rate corresponding to the same region was divided into horizontal and vertical phantom groups.The mean and standard deviation of the obtained ball distortion rates were calculated. Student’s t-test was used to statistically analyze the mean difference in ball distortion rates between vertical and horizontal phantom groups.ResultsIn all devices, the horizontal line pair phantom, but not the vertical line pair phantom, was readable in all areas measured at the line pair value of at least 1.88 lp/mm. The line pair value tended to be higher toward the center and lower toward the outside. The ball distortion rate tended to decrease closer to the center and increased further away. In addition, ball distortion rates could not be measured at some areas as they were not recognized as balls due to the high degree of distortion at the outermost and innermost sides. The number of balls satisfying the reference value using the horizontal line pair phantom was 102 (mean of ball distortion rates, 20.98; standard deviation, 15.25). The number of balls satisfying the reference value using the vertical line pair phantom was 49 (mean of ball distortion rates, 16.33; standard deviation, 14.25). However, mean ball distortion rate was not significantly different between the two groups.ConclusionsFocal layer of panoramic radiography could be evaluated by the spatial resolution using horizontal and vertical line pair phantoms and by assessing ball distortion rates through a ball-type panorama phantom. A ball distortion rate of 20% could be used as a threshold to evaluate the focal layer of panoramic radiography.

Aliasing effects in digital images of line-pair phantoms

2002 ◽  
Vol 29 (8) ◽  
pp. 1716-1718 ◽  
Author(s):  
Michael Albert ◽  
Daniel J. Beideck ◽  
Predrag R. Bakic ◽  
Andrew D. A. Maidment
Keyword(s):  
Digital Images ◽  
Line Pair

The NASA Mass Change Designated Observable Study: Progress and Future Plans

2021 ◽  
Author(s):  
David Wiese ◽  
Bernard Bienstock ◽  
David Bearden ◽  
Carmen Boening ◽  
Kelley Case ◽  
...  
Keyword(s):  
Earth Science ◽  
Mass Change ◽  
Current Status ◽  
Line Pair ◽  
National Academy Of Sciences ◽  
System Architectures ◽  
Study Progress ◽  
Study Process ◽  
Definition Of ◽  
Future Plans

<p>The 2017-2027 US National Academy of Sciences Decadal Survey for Earth Science and Applications from Space classified mass change as one of five designated observables having the highest priority in terms of Earth observations required to better understand the Earth system over the next decade.  In response to this designation, NASA initiated multi-center studies with an overarching goal of defining observing system architectures for each designated observable.  Here, we discuss the progress made and future plans for the Mass Change Designated Observable study. Progress includes the development of a Science and Applications Traceability Matrix (SATM), the definition of three different architectural classes that are responsive to the designated science objectives, and a framework to quantitatively link the performance of specific architectures to the SATM.  We will describe the Value Framework that has been developed to assess the value of potential architectures in terms of science return, cost, risk, and technical maturity.  Results highlight the recommendation of satellite-satellite-tracking for the MC observing system, and have identified high value variants as a single in-line pair, dual in-line pairs, and pendulum architectures, which are similar to architectures studied by potential international partners.  The current status of the study process, and future plans will be discussed.</p>

scholarly journals Using the infrared iron lines to probe solar subsurface convection

2019 ◽  
Vol 630 ◽  
pp. A133 ◽  
Author(s):  
I. Milić ◽  
H. N. Smitha ◽  
A. Lagg
Keyword(s):  
Three Dimensional ◽  
Spectral Lines ◽  
Stray Light ◽  
Line Pair ◽  
Solar Photosphere ◽  
Solar Convection ◽  
Diagnostic Potential ◽  
Optimal Node ◽  
Zero Response ◽  
Magnetohydrodynamic Simulation

Context. Studying the properties of solar convection using high-resolution spectropolarimetry began in the early 1990s with the focus on observations in the visible wavelength regions. Its extension to the infrared (IR) remains largely unexplored. Aims. The IR iron lines around 15 600 Å, most commonly known for their high magnetic sensitivity, also have a non-zero response to line-of-sight (LOS) velocity below log(τ) = 0.0. In this paper we explore the possibility of using these lines to measure subsurface convective velocities. Methods. By assuming a snapshot of a three-dimensional magnetohydrodynamic simulation to represent the quiet Sun, we investigate how well the iron IR lines can reproduce the LOS velocity in the cube and to what depth. We use the recently developed spectropolarimetric inversion code SNAPI and discuss the optimal node placements for the retrieval of reliable results from these spectral lines. Results. We find that the IR iron lines can measure the convective velocities down to log(τ) = 0.5, below the photosphere, not only at the original resolution of the cube, but also when degraded with a reasonable spectral and spatial PSF and stray light. Instead, the commonly used Fe I 6300 Å line pair performs significantly worse. Conclusions. Our investigation reveals that the IR iron lines can probe the subsurface convection in the solar photosphere. This paper is a first step towards exploiting this diagnostic potential.

Confirmation Method of Calibration by Visual Calibration Gauge on Surface Testing

2007 ◽  
Author(s):  
Masako Mori ◽  
Toshibumi Kashiwa ◽  
Yoshimitsu Aoki
Keyword(s):  
Magnetic Particle ◽  
Line Pair ◽  
Optical Instruments ◽  
Japanese Industrial Standard ◽  
Visual Testing ◽  
Magnetic Particle Testing ◽  
Surface Testing

In 2002, Japanese Industrial standard JIS Z 2340 [1] has issued to provide the instruction of new methodology to calibrate the observing conditions of surface testing such as liquid penetrant and magnetic particle testing applying visual calibration gauges. The visual calibration gauges are the transparent plates, on which the line pairs printed to be used to confirm the resolution of visual testing observing view. The concept of line pair has been used to evaluate the resolutions of optical instruments, and the line pair value is a numerical value that shows how many line pairs can be distinguished as separate lines within 1 millimeter. In this paper, the background of the development and the general outlines of visual calibration gauges are introduced at first. And then applications of the gauges and detail process to calibrate the surface testing observing view conditions are also described.

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