COMPUTATIONAL VISUAL SENSITIVITY MODELS — A REVIEW

2004 ◽  
Vol 01 (04) ◽  
pp. 357-369
Author(s):  
ZHONGKANG LU ◽  
ZHERU CHI
Keyword(s):  
Computational Models ◽  
Subjective Evaluation ◽  
Temporal Frequency ◽  
Luminance Contrast ◽  
Visual Sensitivity ◽  
Just Noticeable Difference ◽  
Noise Shaping ◽  
Local Characteristics ◽  
Human Eyes ◽  
Motion Suppression

The Human Visual Systems (HVSs) is imperfect and contains highly selective visual acquisition sensors. Not all useful information presented to human eyes can be perceived. Generally, a technique to determine whether a signal can be perceived and how well it can be perceived is called human visual sensitivity analysis. More than one hundred years of psychophysical research on HVSs has revealed that human visual sensitivity is not only determined by local characteristics of visual contents (luminance, contrast orientation, spatial and temporal frequency), but also global modulatory factors (visual attention and motion suppression). In this paper, we provide a review on various factors that affect human visual sensitivity and on various computational models for human visual sensitivity. A comparative study on the performance of various visual sensitivity models by simulations is also reported in the paper. Subjective evaluation on noise-embedded video sequences confirms that the introduction of global modulatory factors does improve the performance of the Just Noticeable Difference (JND) profile used in noise shaping.

An Ergonomic Evaluation of the Effects of Veiling Reflection on the Human Visibility

2000 ◽  
Vol 44 (21) ◽  
pp. 3-501-3-501
Author(s):  
Jae-Min Park ◽  
Sang-Do Lee ◽  
Young-Sook Kim
Keyword(s):  
Information Search ◽  
Visual Information ◽  
Visual Target ◽  
Subjective Evaluation ◽  
Objective Evaluation ◽  
Luminance Contrast ◽  
Visual Sensitivity ◽  
Working Environment ◽  
Daily Newspapers ◽  
Human Sensibility

Man perceive and react around him through the five senses. Also man give rise to the human sensibility and maintain his emotion. This study doesn't limit working environment to VDT environment, but considers the universal working environment acquiring information by eyesight stimulation. In this respect, designed and made is experimental equipment such as an external light for veiling reflection, visual target suggesting system, and visual target considered luminance contrast level. And reading the visual target is selected as work after excerpting the editorials from daily newspapers in Korean and Chinese letter and making target for experimental condition. In case of forming an abnormal veiling reflection we consider the form; a vertical (25%, 50%, 75%)and a horizontal (25%, 50%, 75%). The results from the subjective evaluation are analyzed by SD (Semantic Differential) methodology of 5 point scale for visibility and nuisance when an abnormal veiling reflection forms on target. In addition, the results of the objective evaluation are suggested by measuring and analyzing EEG (Electroencephalogram) of bio-signal for visual sensitivity. The results of this study can apply to basic data which create a guideline of a visual operation. In particular, it can be designed as an illumination environment concerning an ergonomic factor on visual operations, mental stress such as a visual inspection operation, visual information search operation, etc. As a result, we can expect to reduce the visual nuisance and contribute to the improvement of the performance and the uplift of the competitive power.

Just noticeable difference of sound pressure level of speech in open-plan office

2021 ◽  
Vol 263 (1) ◽  
pp. 5166-5169
Author(s):  
Haram Lee ◽  
Hyunin Jo ◽  
Jin Yong Jeon
Keyword(s):  
Sound Pressure Level ◽  
Sound Pressure ◽  
Paired Comparison ◽  
Subjective Evaluation ◽  
Simulation Models ◽  
Pressure Level ◽  
Just Noticeable Difference ◽  
Sound Sources ◽  
Sound Environment ◽  
Open Plan

In this study, the general sound environment characteristics of open-plan office (OPO) were investigated, and just noticeable difference (JND) of sound pressure level of speech at a distance of 4 m (Lp,A,S,4m) suggested in ISO 3382-3 was suggested. First, in order to understand the sound environment characteristics of OPO, one minute sound sources recorded in 8 offices were collected and physical and psychological acoustic characteristics were analyzed. A total of 30 office workers were subject to subjective evaluation on 8 sound sources, and they were asked to respond to questionnaires related to annoyance, work satisfaction, and speech privacy. Next, to investigate the JND, two computer simulation models identical to those of the actual OPO were implemented, and sound sources each having six different Lp,A,S,4m values were generated through the change of the sound absorption coefficient of the interior finish. The JND of Lp,A,S,4m was presented by performing paired comparison for the same subjects. It is expected that the JND of Lp,A,S,4m proposed in this study can be used for the sound environment rating of OPO.

scholarly journals What Color Does the Consumer See? Perceived Color Differences in Plastic Products in an LED-Lit Environment

2019 ◽  
Vol 11 (21) ◽  
pp. 5985 ◽  
Author(s):  
Xiao Dou ◽  
Chih-Fu Wu ◽  
Kai-Chieh Lin ◽  
Jeih-Jang Liou
Keyword(s):  
Acrylonitrile Butadiene Styrene ◽  
Visual Sensitivity ◽  
Color Temperature ◽  
Light Sources ◽  
Color Differences ◽  
Market Opportunities ◽  
Actual Color ◽  
Human Eyes ◽  
Perceived Color ◽  
Plastic Products

To attract customers and increase market opportunities, retailers frequently use lighting to highlight the color of their products. However, differences between perceived and actual color, triggered by display lighting, can motivate buyers to discard products after purchase. Few studies have been reported on differences in perceived color, caused by LEDs. This study focuses on two correlated color temperatures (2800 K, 4000 K) and illuminance levels (500 lx, 1500 lx) to create four LED-lit environments, and measures the differences in the color perceived by 20 observers on acrylonitrile–butadiene–styrene (ABS) plastics, with different surfaces, under these four environments. The results reveal that correlated color temperature results in larger perceived differences in color than illuminance, and the effects of LED light sources on green and yellow ABS plastic products are more obvious than their effects on red and blue products. One possible reason for this can be attributed to the visual sensitivity effect of human eyes. The results of this study can serve as a reference for designers fabricating ABS plastic products for practical lighting applications, and improving the role of LED lighting in sustainable development.

Perception of a Border Defined by Rapidly Reversing Luminance Contrast

1997 ◽  
Vol 84 (3) ◽  
pp. 739-746
Author(s):  
Kyoungmin Lee ◽  
Joy Hirsch
Keyword(s):  
Visual Illusion ◽  
Temporal Frequency ◽  
Luminance Contrast ◽  
Fusion Rate ◽  
Luminance Threshold

We report a new visual illusion of a perceptual boundary visible between two contiguous regions of equal luminance when the intensity is modulated with a temporal frequency that is higher than the critical fusion rate. Measurements of the luminance threshold of the perceptual border with various slopes of the luminance gradient yielded a function suggestive of the range of ocular instability. These findings raise the possibility that this new border illusion may be influenced by involuntary ocular motion during fixation.

scholarly journals A subjective evaluation of noise-shaping quantization for adaptive intra-/interframe DPCM coding of color television signals

1988 ◽  
Vol 36 (3) ◽  
pp. 332-346 ◽  
Author(s):  
B. Girod ◽  
H. Almer ◽  
L. Bengtsson ◽  
B. Christensson ◽  
P. Weiss
Keyword(s):  
Subjective Evaluation ◽  
Noise Shaping ◽  
Color Television

scholarly journals An asymmetric outer retinal response to drifting sawtooth gratings

2016 ◽  
Vol 115 (5) ◽  
pp. 2349-2358 ◽  
Author(s):  
Nina Riddell ◽  
Laila Hugrass ◽  
Jude Jayasuriya ◽  
Sheila G. Crewther ◽  
David P. Crewther
Keyword(s):  
Perceptual Experience ◽  
Temporal Frequency ◽  
Luminance Contrast ◽  
Potential Effect ◽  
Sine Wave ◽  
Frame Rate ◽  
Frequency Effects ◽  
Dc Potential ◽  
The Difference ◽  
Retinal Response

Electroretinogram (ERG) studies have demonstrated that the retinal response to temporally modulated fast-ON and fast-OFF sawtooth flicker is asymmetric. The response to spatiotemporal sawtooth stimuli has not yet been investigated. Perceptually, such drifting gratings or diamond plaids shaded in a sawtooth pattern appear brighter when movement produces fast-OFF relative to fast-ON luminance profiles. The neural origins of this illusion remain unclear (although a retinal basis has been suggested). Thus we presented toad eyecups with sequential epochs of sawtooth, sine-wave, and square-wave gratings drifting horizontally across the retina at temporal frequencies of 2.5–20 Hz. All ERGs revealed a sustained direct-current (DC) transtissue potential during drift and a peak at drift offset. The amplitudes of both phenomena increased with temporal frequency. Consistent with the human perceptual experience of sawtooth gratings, the sustained DC potential effect was greater for fast-OFF cf. fast-ON sawtooth. Modeling suggested that the dependence of temporal luminance contrast on stimulus device frame rate contributed to the temporal frequency effects but could not explain the divergence in response amplitudes for the two sawtooth profiles. The difference between fast-ON and fast-OFF sawtooth profiles also remained following pharmacological suppression of postreceptoral activity with tetrodotoxin (TTX), 2-amino-4-phosphonobutric acid (APB), and 2,3 cis-piperidine dicarboxylic acid (PDA). Our results indicate that the DC potential difference originates from asymmetries in the photoreceptoral response to fast-ON and fast-OFF sawtooth profiles, thus pointing to an outer retinal origin for the motion-induced drifting sawtooth brightness illusion.

Spatial structure of chromatically opponent receptive fields in the human visual system

1995 ◽  
Vol 12 (1) ◽  
pp. 103-116 ◽  
Author(s):  
Pascal Girard ◽  
Maria Concetta Morrone
Keyword(s):  
Temporal Frequency ◽  
Receptive Fields ◽  
Local Variation ◽  
Luminance Contrast ◽  
Response Curves ◽  
Chromatic Contrast ◽  
Phase Discrimination ◽  
Human Color Vision ◽  
Contrast Thresholds ◽  
Contrast Response

AbstractThis study investigates the receptive-field structure of mechanisms operating in human color vision, by recording visual evoked potentials (VEPs) to multiharmonic gratings modulated either in luminance or color (red-green). Varying the Fourier phase of the harmonics from 0 deg to 90 deg produced a family of stimulus profiles that varied from lines to edges. The stimuli were contrast reversed to elicit steady-state VEPS, and also randomly jittered (at a higher temporal frequency than the contrast reversal) to ensure that the evoked response resulted from the polarity reversal, rather than from local variation of luminance or color. Reliable VEPs were recorded from both luminance and chromatic stimuli at all phases, suggesting that the mechanisms sensitive to chromatic contrast and those sensitive to luminance contrast have both symmetric and asymmetric receptive fields. Contrast thresholds estimated by extrapolation of the contrast response curves were very similar to psychophysical thresholds for phase discrimination, suggesting that the VEP response is generated by mechanisms mediating phase discrimination. The results support the idea that human color mechanisms have receptive fields with a variety of spatial symmetries (including odd- and even-symmetric fields) and that these mechanisms may contribute to phase discrimination of chromatic stimuli in a similar way to what has been suggested for luminance vision.

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