Limitations on contrast sensitivity and dynamic range imposed by human-eye response characteristics, film-density, and radiographic viewing conditions

1993 ◽  
Author(s):  
Earle L. Kitts, Jr.
Keyword(s):  
Contrast Sensitivity ◽  
Dynamic Range ◽  
Film Density ◽  
Human Eye ◽  
Response Characteristics

The mechanical basis of Drosophila audition

2002 ◽  
Vol 205 (9) ◽  
pp. 1199-1208 ◽  
Author(s):  
Martin C. Göpfert ◽  
Daniel Robert
Keyword(s):  
Mechanical Response ◽  
Dynamic Range ◽  
Near Field ◽  
Sense Organ ◽  
Field Measurements ◽  
Longitudinal Axis ◽  
Acoustic Energy ◽  
Linear Effect ◽  
Response Characteristics ◽  
Non Linear

SUMMARY In Drosophila melanogaster, antennal hearing organs mediate the detection of conspecific songs. Combining laser Doppler vibrometry, acoustic near-field measurements and anatomical analysis, we have investigated the first steps in Drosophila audition, i.e. the conversion of acoustic energy into mechanical vibrations and the subsequent transmission of vibrations to the auditory receptors in the base of the antenna. Examination of the mechanical responses of the antennal structures established that the distal antennal parts (the funiculus and the arista) together constitute a mechanical entity, the sound receiver. Unconventionally, this receiver is asymmetric, resulting in an unusual, rotatory pattern of vibration; in the presence of sound, the arista and the funiculus together rotate about the longitudinal axis of the latter. According to the mechanical response characteristics, the antennal receiver represents a moderately damped simple harmonic oscillator. The receiver's resonance frequency increases continuously with the stimulus intensity, demonstrating the presence of a non-linear stiffness that may be introduced by the auditory sense organ. This surprising,non-linear effect is relevant for close-range acoustic communication in Drosophila; by improving antennal sensitivity at low song intensities and reducing sensitivity when intensity is high, it brings about dynamic range compression in the fly's auditory system.

scholarly journals Nonlinear tuning of microresonators for dynamic range enhancement

2015 ◽  
Vol 471 (2179) ◽  
pp. 20140969 ◽  
Author(s):  
M. Saghafi ◽  
H. Dankowicz ◽  
W. Lacarbonara
Keyword(s):  
Nonlinear Response ◽  
Dynamic Range ◽  
Multiple Scales ◽  
Method Of Multiple Scales ◽  
Equations Of Motion ◽  
Path Following ◽  
Critical Amplitude ◽  
Inertia Effects ◽  
Response Characteristics ◽  
The Galerkin Method

This paper investigates the development of a novel framework and its implementation for the nonlinear tuning of nano/microresonators. Using geometrically exact mechanical formulations, a nonlinear model is obtained that governs the transverse and longitudinal dynamics of multilayer microbeams, and also takes into account rotary inertia effects. The partial differential equations of motion are discretized, according to the Galerkin method, after being reformulated into a mixed form. A zeroth-order shift as well as a hardening effect are observed in the frequency response of the beam. These results are confirmed by a higher order perturbation analysis using the method of multiple scales. An inverse problem is then proposed for the continuation of the critical amplitude at which the transition to nonlinear response characteristics occurs. Path-following techniques are employed to explore the dependence on the system parameters, as well as on the geometry of bilayer microbeams, of the magnitude of the dynamic range in nano/microresonators.

scholarly journals Spatio-chromatic contrast sensitivity across the life span: interactions between age and light level in high dynamic range

2020 ◽  
Vol 20 (11) ◽  
pp. 1286
Author(s):  
Maliha Ashraf ◽  
Sophie Wuerger ◽  
Minjung Kim ◽  
Helen Saunderson ◽  
Jasna Martinovic ◽  
...  
Keyword(s):  
Life Span ◽  
Contrast Sensitivity ◽  
Dynamic Range ◽  
High Dynamic Range ◽  
Light Level ◽  
Chromatic Contrast ◽  
High Dynamic ◽  
Chromatic Contrast Sensitivity

scholarly journals Practical Color Contrast Sensitivity Functions for Luminance Levels up to 10000 cd/m2

2020 ◽  
Vol 2020 (28) ◽  
pp. 1-6
Author(s):  
Rafał K. Mantiuk ◽  
Minjung Kim ◽  
Maliha Ashraf ◽  
Qiang Xu ◽  
M. Ronnier Luo ◽  
...  
Keyword(s):  
Contrast Sensitivity ◽  
Dynamic Range ◽  
Color Space ◽  
High Dynamic Range ◽  
Model Parameters ◽  
Color Contrast ◽  
Sensitivity Functions ◽  
Spatial Frequencies ◽  
Wide Range ◽  
Opponent Color

We model color contrast sensitivity for Gabor patches as a function of spatial frequency, luminance and chromacity of the background, modulation direction in the color space and stimulus size. To fit the model parameters, we combine the data from five independent datasets, which let us make predictions for background luminance levels between 0.0002 cd/m2 and 10 000 cd/m2, and for spatial frequencies between 0.06 cpd and 32 cpd. The data are well-explained by two models: a model that encodes cone contrast and a model that encodes postreceptoral, opponent-color contrast. Our intention is to create practical models, which can well explain the detection performance for natural viewing in a wide range of conditions. As our models are fitted to the data spanning very large range of luminance, they can find applications in modeling visual performance for high dynamic range and augmented reality displays.

scholarly journals OCCHIO E VISIONE: MERAVIGLIA DELLA NATURA O PROGETTO DIFETTOSO?

2020 ◽  
Author(s):  
Pier Giorgio Gobbi
Keyword(s):  
Visual System ◽  
Physical Model ◽  
Temporal Resolution ◽  
Human Visual System ◽  
Dynamic Range ◽  
Evolutionary Design ◽  
Human Eye ◽  
Quantitative Estimates ◽  
Chromatic Aberrations

The behavior of the human visual system exhibits some flaws, including monochromatic and chromatic aberrations, finite dynamic range, limited spatial and temporal resolution. Why did it evolve this way? Can it be improved somehow, for example with the support of technology? The answer is obtained from a neuro-physical model developed by the author, which provides quantitative estimates of the optical and visual performances of the human eye, in agreement with experimental records. The conclusion, based on the principle of utility, is that the evolutionary design of the visual system is perfectly tailored for the primary survival needs of our primitive ancestors in daylight illumination, and it can hardly be improved with the help of human technology.

scholarly journals Spatio-chromatic contrast sensitivity across the lifespan: interactions between age and light level in high dynamic range

2020 ◽  
Vol 2020 (28) ◽  
pp. 65-69
Author(s):  
Maliha Ashraf ◽  
Sophie Wuerger ◽  
Minjung Kim ◽  
Jasna Martinovic ◽  
Rafał K. Mantiuk
Keyword(s):  
Contrast Sensitivity ◽  
Dynamic Range ◽  
High Dynamic Range ◽  
Light Level ◽  
Background Luminance ◽  
Age Group ◽  
Chromatic Contrast ◽  
Achromatic Contrast ◽  
High Dynamic ◽  
Chromatic Contrast Sensitivity

We investigated spatio-chromatic contrast sensitivity in both younger and older color-normal observers. We tested how the adapting light level affected the contrast sensitivity and whether there was a differential age-related change in sensitivity. Contrast sensitivity was measured along three directions in colour space (achromatic, red-green, yellowish-violet), at background luminance levels from 0.02 to 2000 cd/m2, and different stimuli sizes using 4AFC method on a high dynamic range display. 20 observers with a mean age of 33 y. o. a. and 20 older observers with mean age of 65 participated in the study. Within each session, observers were fully adapted to the fixed background luminance. Our main findings are: (1) Contrast sensitivity increases with background luminance up to around 200 cd/m2, then either declines in case of achromatic contrast sensitivity, or remains constant in case of chromatic contrast sensitivity; (2) The sensitivity of the younger age group is higher than that for the older age group by 0.3 log units on average. Only for the achromatic contrast sensitivity, the old age group shows a relatively larger decline in sensitivity for medium to high spatial frequencies at high photopic light levels; (3) Peak frequency, peak sensitivity and cut-off frequency of contrast sensitivity functions show decreasing trends with age and the rate of this decrease is dependent on mean luminance. The data is being modeled to predict contrast sensitivity as a function of age, luminance level, spatial frequency, and stimulus size.

Coding Strategies in Monkey V1 and Inferior Temporal Cortices

1998 ◽  
Vol 79 (3) ◽  
pp. 1135-1144 ◽  
Author(s):  
Ethan D. Gershon ◽  
Matthew C. Wiener ◽  
Peter E. Latham ◽  
Barry J. Richmond
Keyword(s):  
Channel Capacity ◽  
Gaussian Distribution ◽  
Dynamic Range ◽  
Spike Count ◽  
Neuronal Responses ◽  
Response Characteristics ◽  
Cortical Areas ◽  
Count Response ◽  
Coding Strategies ◽  
The Mean

Gershon, Ethan D., Matthew C. Wiener, Peter E. Latham, and Barry J. Richmond. Coding strategies in monkey V1 and inferior temporal cortices. J. Neurophysiol. 79: 1135–1144, 1998. We would like to know whether the statistics of neuronal responses vary across cortical areas. We examined stimulus-elicited spike count response distributions in V1 and inferior temporal (IT) cortices of awake monkeys. In both areas, the distribution of spike counts for each stimulus was well described by a Gaussian distribution, with the log of the variance in the spike count linearly related to the log of the mean spike count. Two significant differences in response characteristics were found: both the range of spike counts and the slope of the log(variance) versus log(mean) regression were larger in V1 than in IT. However, neurons in the two areas transmitted approximately the same amount of information about the stimuli and had about the same channel capacity (the maximum possible transmitted information given noise in the responses). These results suggest that neurons in V1 use more variable signals over a larger dynamic range than IT neurons, which use less variable signals over a smaller dynamic range. The two coding strategies are approximately as effective in transmitting information.

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