The Sensitivity Performance of the Human Eye on an Absolute Scale*

Rose, Albert

doi:10.1364/josa.38.000196

Cited by 823 publications

(381 citation statements)

References 15 publications

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“…This assessed the negative impact of z ‐axial PVE on the detection of low‐contrasted objects, and is consistent with results obtained in a previous study 22. A straightforward relationship between CNR and detection was confirmed, as expected by the Rose model for the considered conditions (objects of low contrast in homogeneous noisy background) 23. Detectability and CNR of subslice targets followed a sigmoidal function, in agreement with Weber's law.…”

Section: Discussionsupporting

confidence: 81%

Optimal slice thickness for object detection with longitudinal partial volume effects in computed tomography

Monnin¹,

Sfameni²,

Gianoli³

et al. 2016

J Applied Clin Med Phys

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Longitudinal partial volume effects (z‐axial PVE), which occur when an object partly occupies a slice, degrade image resolution and contrast in computed tomography (CT). Z‐axial PVE is unavoidable for subslice objects and reduces their contrast according to their fraction contained within the slice. This effect can be countered using a smaller slice thickness, but at the cost of an increased image noise or radiation dose. The aim of this study is to offer a tool for optimizing the reconstruction parameters (slice thickness and slice spacing) in CT protocols in the case of partial volume effects. This optimization is based on the tradeoff between axial resolution and noise. For that purpose, we developed a simplified analytical model investigating the average statistical effect of z‐axial PVE on contrast and contrast‐to‐noise ratio (CNR). A Catphan 500 phantom was scanned with various pitches and CTDI and reconstructed with different slice thicknesses to assess the visibility of subslice targets that simulate low contrast anatomical features present in CT exams. The detectability score of human observers was used to rank the perceptual image quality against the CNR. Contrast and CNR reduction due to z‐axial PVE measured on experimental data were first compared to numerical calculations and then to the analytical model. Compared to numerical calculations, the simplified algebraic model slightly overestimated the contrast but the differences remained below 5%. It could determine the optimal reconstruction parameters that maximize the objects visibility for a given dose in the case of z‐axial PVE. An optimal slice thickness equal to three‐fourth of the object width was correctly proposed by the model for nonoverlapping slices. The tradeoff between detectability and dose is maximized for a slice spacing of half the slice thickness associated with a slice width equal to the characteristic object width.

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Section: Discussionsupporting

confidence: 81%

Optimal slice thickness for object detection with longitudinal partial volume effects in computed tomography

Monnin¹,

Sfameni²,

Gianoli³

et al. 2016

J Applied Clin Med Phys

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“…At low values of I, @e-optimum photoreceptor spacing is given by 1.4(jr C)-"z, i.e. it is independent of pupil diffraction and follows the weti-known square root law of an idea1 detector (Barlow, 1964;Rose, 1973). As the intensity increases, the optimum spacing approaches the limit set by pupil diffraction, i.e.…”

Section: Eye Design and Spatial Information Capacitymentioning

confidence: 97%

Information capacity of eyes

1977

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“…At high light intensities, the dominant source of noise in the rods is quantum fluctuation, and this is proportional to the square root of the intensity (Rose, 1948;Shapley and Enroth-Cugell, 1984). In this condition, where noise is related to light intensity, there would be no penalty for pooling the voltages of many rods in the cone pedicle rather than pooling them at a later stage.…”

Section: Modulation Of the Gap Junctionsmentioning

confidence: 99%

Microcircuitry of the dark-adapted cat retina: functional architecture of the rod-cone network

Smith¹,

Freed²,

Sterling³

1986

J. Neurosci.

230

186

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The structure of the rod-cone network in the area centralis of cat retina was studied by reconstruction from serial electron micrographs. About 48 rods converge on each cone via gap junctions between the rod spherules and the basal processes of the cone pedicle. One rod diverges to 2.4 cones through these gap junctions, and each cone connects to 8 other cones, also through gap junctions. A static cable model of this network showed that at mesopic intensities, when all rods converging on a cone pedicle are continuously active, the collective rod signal would be efficiently conveyed to the pedicle. At scotopic intensities sufficiently low for only one of the converging rods to receive a single photon within its integration time, the quantal rod signal would be poorly transmitted to the cone pedicle. This is because the tiny signal would be dissipated by the large network into which the individual rod diverges. Under this condition, the rod signal would also be poorly conveyed to the rod spherule. If, however, the rods are electrically disconnected from the network, the quantal signal would be efficiently conveyed to the rod spherule. This analysis suggests that the rod signal is conveyed at mesopic intensities by the cone bipolar pathway and, at scotopic intensities, by the rod bipolar pathway, in accordance with the results of Nelson (1977, 1982; Nelson and Kolb, 1985).

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The Sensitivity Performance of the Human Eye on an Absolute Scale*

Cited by 823 publications

References 15 publications

Optimal slice thickness for object detection with longitudinal partial volume effects in computed tomography

Optimal slice thickness for object detection with longitudinal partial volume effects in computed tomography

Information capacity of eyes

Microcircuitry of the dark-adapted cat retina: functional architecture of the rod-cone network

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