19.1: The Visibility of a Global Luminance Profile of a Display

2003 ◽  
Vol 34 (1) ◽  
pp. 816 ◽  
Author(s):  
I. Heynderickx ◽  
I. Vogels ◽  
S. Swinkels ◽  
S. Bech ◽  
E. Mastenbroek
Keyword(s):  
Luminance Profile

scholarly journals A New Method of Measuring Retinal Vessel Diameters from Fundus Photographs Based on Retinal Structure and Light Reflection

2021 ◽  
Author(s):  
Satoshi Wakebe ◽  
Kotaro Yamasue ◽  
Hidetoshi Itoh
Keyword(s):  
Blood Vessel ◽  
Diffuse Reflection ◽  
Repeated Measurement ◽  
New Method ◽  
Dimensional Structure ◽  
Cylindrical Shape ◽  
Reflection Model ◽  
Luminance Profile ◽  
Fundus Photographs ◽  
Minimum Points

<p>We propose a new method and software for measuring blood vessel diameters from fundus photographs. In this method the edge of the blood vessel is the two minimum points in the luminance profile and diameter is distance between minimum points. We noticed the relation between W-shape of luminance profile at blood vessel transversal line and cylindrical shape, and analyzed the validity of this method using the diffuse reflection model of a cylinder shape based on the optics. The simulation image by the diffuse reflection model of the cylinder was similar to that of the blood vessel images. A newly developed software using the minimum points can measure repeated measurement in a series of photographs at the same point of the same person. The data of the repeated measurement of each person showed stability, and the coefficient of variation showed no affection of different diameter and arteriovenous distinction. Hence, we believe that the minimum points are valid as blood vessel edges. The software that measures these blood vessel edges has an extremely simple measurement procedure, possesses few errors, and is easy to automate. This method is relevant because the central reflex, which has not been utilized previously, optically represents the cylindrical three-dimensional structure of blood vessels.</p><div><div> </div> </div>

scholarly journals A New Method of Measuring Retinal Vessel Diameters from Fundus Photographs Based on Retinal Structure and Light Reflection

2021 ◽  
Author(s):  
Satoshi Wakebe ◽  
Kotaro Yamasue ◽  
Hidetoshi Itoh
Keyword(s):  
Blood Vessel ◽  
Diffuse Reflection ◽  
Repeated Measurement ◽  
New Method ◽  
Dimensional Structure ◽  
Cylindrical Shape ◽  
Reflection Model ◽  
Luminance Profile ◽  
Fundus Photographs ◽  
Minimum Points

<p>We propose a new method and software for measuring blood vessel diameters from fundus photographs. In this method the edge of the blood vessel is the two minimum points in the luminance profile and diameter is distance between minimum points. We noticed the relation between W-shape of luminance profile at blood vessel transversal line and cylindrical shape, and analyzed the validity of this method using the diffuse reflection model of a cylinder shape based on the optics. The simulation image by the diffuse reflection model of the cylinder was similar to that of the blood vessel images. A newly developed software using the minimum points can measure repeated measurement in a series of photographs at the same point of the same person. The data of the repeated measurement of each person showed stability, and the coefficient of variation showed no affection of different diameter and arteriovenous distinction. Hence, we believe that the minimum points are valid as blood vessel edges. The software that measures these blood vessel edges has an extremely simple measurement procedure, possesses few errors, and is easy to automate. This method is relevant because the central reflex, which has not been utilized previously, optically represents the cylindrical three-dimensional structure of blood vessels.</p><div><div> </div> </div>

scholarly journals Lightness constancy: Ratio invariance and luminance profile

2009 ◽  
Vol 71 (3) ◽  
pp. 463-470 ◽  
Author(s):  
A. Soranzo ◽  
A. Galmonte ◽  
T. Agostini
Keyword(s):  
Lightness Constancy ◽  
Luminance Profile

Visually Evoked Magnetic Field Induced by Ring Motion Aftereffect

Perception ◽  
1997 ◽  
Vol 26 (1_suppl) ◽  
pp. 301-301
Author(s):  
N Osaka ◽  
M Osaka ◽  
S Koyama ◽  
R Kakigi
Keyword(s):  
Magnetic Field ◽  
Goodness Of Fit ◽  
Visual Motion ◽  
Motion Aftereffect ◽  
Adaptation Period ◽  
Luminance Profile ◽  
The Subject ◽  
The Right ◽  
Clear Increase ◽  
Good Agreement

Motion aftereffect (MAE) is a negative aftereffect caused by prolonged viewing of visual motion: after gazing at a moving grating for a while, a stationary image will appear to move in the opposite direction (Ashida and Osaka, 1995 Vision Research35 1825). Evoked magnetic field (magnetoencephalogram: MEG) was measured when a human subject observing ring MAE in which concentric circles appear to contract continuously after viewing continuously expanding rings. The diameter of the stimulus was 20 deg with fixation point in the centre. The magnetic evoked field (80 averagings at a latency of 190 ms) was measured from 37 points over the occipital and parietal areas (Magnes SQUID biomagnetometer, BTi) while the subject was observing stationary rings after an adaptation period of 2 s at low spatial frequency (4 cycles deg−1, 4 Hz). The luminance profile was sinusoidally changed across rings. MRI image fitting (sagittal, coronal, and axial view) for each of four subjects, and dipole estimates obtained for equal magnetic field contours (with value of goodness of fit greater than 0.98) from the right brain hemisphere suggest that the main loci subserving MAE lie in the surrounding region over the lateral occipitotemporal areas in the human brain, close to area MT. This is in good agreement with another study with fMRI-based MAE measures [Tootell et al, 1995 Nature (London)375 139] in which a clear increase in activity in these areas was observed when subjects viewed MAE.

Spatial phase or luminance profile discrimination?

1984 ◽  
Vol 24 (6) ◽  
pp. 613-623 ◽  
Author(s):  
David R. Badcock
Keyword(s):  
Spatial Phase ◽  
Luminance Profile

Luminance profile control method using gradation iris for autostereoscopic 3D displays

2015 ◽  
Author(s):  
Munekazu Date ◽  
Tohru Kawakami ◽  
Mutsumi Sasai ◽  
Hideaki Takada
Keyword(s):  
Control Method ◽  
Luminance Profile ◽  
Profile Control ◽  
3D Displays

Selective Attention to Specific Location Cues: The Peak and Center of a Patch are Equally Accessible as Location Cues

Perception ◽  
1998 ◽  
Vol 27 (9) ◽  
pp. 1015-1023 ◽  
Author(s):  
Hiromi Akutsu ◽  
Dennis M Levi
Keyword(s):  
Visual System ◽  
Spatial Localization ◽  
Second Derivative ◽  
Specific Location ◽  
Zero Crossings ◽  
Luminance Distribution ◽  
Luminance Profile ◽  
Asymmetric Pattern ◽  
Visible Area ◽  
At Will

Asymmetric patterns have several spatially distinct cues for spatial localization. These cues include the peak of the luminance distribution, the centroid of the contrast distribution, zero-crossings in the second derivative of the luminance profile, and the midpoint of the visible area. If these cues are represented as primitives in the visual system, the observer should be able to access them at will. To examine whether observers can selectively attend to particular cues, we measured perceived alignment for an asymmetric pattern with two distinct instructions: “align the peak”, and “align the center”. We found that observers could align the patterns in accord with the instructions with identical precision, suggesting that the peak and the center cues were equally accessible by the observer. We conclude that multiple localization cues are represented in and can be selectively accessed by the visual system.

Visibility of blobs with a gaussian luminance profile

1989 ◽  
Vol 29 (4) ◽  
pp. 447-456 ◽  
Author(s):  
P. Bijl ◽  
J.J. Koenderink ◽  
A. Toet
Keyword(s):  
Luminance Profile

The Dependence of Monocular Rivalry on Orientation

Perception ◽  
1973 ◽  
Vol 2 (2) ◽  
pp. 123-125 ◽  
Author(s):  
F W Campbell ◽  
A S Gilinsky ◽  
E R Howell ◽  
L A Riggs ◽  
J Atkinson
Keyword(s):  
Visual Cortex ◽  
Medical Research ◽  
Maximum Rate ◽  
National Science Foundation ◽  
Research Council ◽  
Medical Research Council ◽  
The Other ◽  
Luminance Profile ◽  
National Science ◽  
Research Grant

If two gratings with a sinusoidal luminance profile are crossed and if each has a different colour then they are seen to alternate; first one dominates and then the other. Part of the time both are seen. The rate of this monocular rivalry varies with the angle between the two gratings. If the two are lined up in parallel the percept is quite stable and remains so until their orientation is about 15° to 20° apart. The rate of alternation then increases rapidly reaching a maximum rate of 30 per minute. The orientational selectivity of the rivalry suggests that the orientational properties of the neurones in the visual cortex discovered by Hubel and Wiesel are involved. Acknowledgements. We wish to thank Professor Peter M. Milner for his keen interest in these experiments and for acting as a subject. F.W.C. is supported by a grant from the Medical Research Council. The work of A.S.G. during her visit to Cambridge was supported in part by a research grant GB-31029 from the National Science Foundation. E.R.H. was awarded a Wellcome Trust Fellowship while in Cambridge.

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