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.

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.

Receptor potentials of isolated frog muscle spindle evoked by sinusoidal stimulation

1985 ◽  
Vol 53 (1) ◽  
pp. 60-75 ◽  
Author(s):  
H. Querfurth
Keyword(s):  
Dynamic Range ◽  
Stimulus Frequency ◽  
Receptor Potential ◽  
Muscle Spindles ◽  
Response Characteristic ◽  
Phase Lag ◽  
Half Cycle ◽  
Static Stretch ◽  
Response Characteristics ◽  
Dc Component

Receptor potentials in response to sinusoidal stimulation have been recorded from isolated muscle spindles of the frog. Sinusoidal displacements of different amplitudes (20-120 micron) and frequencies (0.1-100 Hz) were used. The mean static stretch level was adjusted between resting length (L0) and L0 + 400 micron, so that the amplitude and phase-response characteristics were measured at different operating points. Depending on the amount of static prestretch, there is a well-defined dynamic range, which limits the receptor potential by nonlinear compression of either its positive or negative half-cycle. For each point on the static operating curve there exists a dynamic operating curve with a sigmoidal shape. The range of each dynamic curve is approximately 80 micron, independent of the static displacement, and the maxima of all dynamic curves are the same. Therefore the dynamic curves are not symmetrical about their static operating point. The slope of the steepest portion is 10% of the maximum elicitable receptor potential per 10-micron dynamic displacement. For stimulus frequencies greater than 2 Hz the receptor potential deviates from a sinusoidal waveform, exhibiting a fast depolarization transient during stretch and a prolonged repolarization transient during release of stretch. The steepness of the depolarization transient increases with increasing stimulus frequency, amplitude, and prestretch level. As a result, the interval from trough to peak of the receptor potential shortens to less than 90 degrees instead of half a cycle. The repolarization transient has an exponential decay with a time constant of approximately 40 ms that remains constant during the various stimulus conditions. As a result of this slow decay time, individual receptor potentials summate, so that the response divides into a modulated receptor potential (AC component) and a maintained depolarization (DC component). The amplitude response characteristic of the stationary AC component increases with increasing stimulus frequencies up to a peak at 2 Hz, after which it declines with a slope of -3 dB/octave. Provided large sinusoidal stretches and/or extended prestretch levels are used, this high-frequency decline of the AC component is compensated for by the proportional increase of the DC component, so that the peak depolarization values remain constant from 2 to 100 Hz. Stimulus and response are in phase for stimulus frequencies less than 2 Hz and reverse to phase lag at higher stimulus frequencies.(ABSTRACT TRUNCATED AT 400 WORDS)

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