Effective contrast of colored stimuli in the mesopic range: a metric for perceived contrast based on achromatic luminance contrast

Walkey, Helen C.; Barbur, John L.; Harlow, J.A.; Hurden, Antony; Moorhead, Ian R.; Taylor, J.

doi:10.1364/josaa.22.000017

Cited by 26 publications

(24 citation statements)

References 38 publications

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“…Given the importance of response speed in many real-world applications, RT paradigms are currently being investigated as potential methods for deriving mesopic luminous efficiency functions [29,31–34]. To be used in this application, RT must be mediated via the MC pathway, the candidate physiological substrate of photopic luminous efficiency function V(λ) [35].…”

Section: Introductionmentioning

confidence: 99%

Effect of rod–cone interactions on mesopic visual performance mediated by chromatic and luminance pathways

et al. 2013

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We studied the effect of rod–cone interactions on mesopic visual reaction time (RT). Rod and cone photoreceptor excitations were independently controlled using a four-primary photostimulator. It was observed that (1) lateral rod–cone interactions increase the cone-mediated RTs; (2) the rod–cone interactions are strongest when rod sensitivity is maximal in a dark surround, but weaker with increased rod activity in a light surround; and (3) the presence of a dark surround nonselectively increased the mean and variability of chromatic (+L−M, S-cone) and luminance (L + M + S) RTs independent of the level of rod activity. The results demonstrate that lateral rod–cone interactions must be considered when deriving mesopic luminous efficiency using RT.

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Section: Introductionmentioning

confidence: 99%

Effect of rod–cone interactions on mesopic visual performance mediated by chromatic and luminance pathways

et al. 2013

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“…There is psychophysical, physiological, and anatomical evidence that luminance~Cicerone et al., 1986;Whittle, 1986;Schiller, 1992;Walkey et al, 2005! Generally, observers set larger chromatic differences for both increments and decrements, which is consistent with observers being less sensitive to chromatic differences at low luminances.…”

Section: Discussionmentioning

confidence: 99%

Changes in induced hues at low luminance and following dark adaptation suggest rod-cone interactions may differ for luminance increments and decrements

Shepherd

Wyatt

2008

Vis Neurosci

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Color contrast describes the influence of one color on the perception of colors in neighboring areas. This study addressed two issues: (1) the accurate representation of the color changes; (ii) the underlying visual mechanisms. Observers matched the hue that was induced in a neutral square when it was set in one of four standard colored surrounds: "red" (+L(-M) relative to neutral), "green" (-L(+M)), "purple" (+S), and "yellow" (-S). The standard and matching displays were viewed haploscopically. The standard neutral square was either a luminance increment, or decrement, both of which appeared the complementary color to the surrounds in which they were inset. In Experiment 1, the surround luminance in each eye's display was either equal, at 18 cd x m(-2), or the match surround luminance was reduced to 2.5 cd x m(-2). The matches with equal surround luminances could be represented as vector shifts in a logarithmic MacLeod-Boynton (r, b) chromaticity diagram, as described previously (Shepherd, 1997, 1999). The low luminance matches were, however, displaced further from neutral, as if larger chromatic differences were needed. The precise direction of the displacements differed for luminance increments and decrements: the red, green and yellow decrement matches were also displaced vertically downwards in the MacLeod-Boynton diagram. In Experiment 2, dark-adapting before setting repeat color matches displaced the decrement matches vertically, but did not affect the increment matches. Thus, rod intrusion in S-cone pathways may have boosted the S-cone signal for the lowest luminance decrement matches in Experiment 1 and account for the vertical shift in MacLeod-Boynton co-ordinates. The distinct pattern of displacements for low luminance increments and decrements may be explained if the match is set at a cone-opponent, rather than a cone contrast, site and if rod signals have an input only to S-cone decrement, perhaps S-OFF, pathways.

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“…When objects have low luminance contrast, the addition of colour signals, particularly to targets defined by luminance increments, results in improved visual performance and shorter TCTs. [3][4][5] Parallel processing and pop-out A fundamental property of colour mechanisms in human vision that yields significant advantages in visual search is the independent processing of colour and luminance contrast signals. [6][7][8] The existence of different visual mechanisms dedicated to the processing of colour signals also means that objects defined by colour are resilient to achromatic background clutter.…”

Section: Enhancement Of Object Conspicuitymentioning

confidence: 99%

Colour vision requirements in visually demanding occupations

Barbur¹,

Rodriguez‐Carmona²

2017

British Medical Bulletin

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Normal trichromatic colour vision (CV) is often required as a condition for employment in visually demanding occupations. If accurate CV tests were available Q2 to enforce this requirement, a significant percentage of subjects with anomalous, congenital trichromacy who can perform the suprathreshold, colour-related tasks encountered in many occupations with the same accuracy as normal trichromats would fail. These applicants would therefore be discriminated against unfairly. One solution to this problem is to produce minimum, justifiable CV requirements that are specific to each occupation. This has been done successfully for commercial aviation (i.e. the flight crew) and for Transport for London train drivers. An alternative approach is to make use of new findings and the statistical outcomes of past practices to produce graded, justifiable CV categories that can be enforced. To achieve this aim, we analysed colour assessment outcomes and quantified severity of CV loss in 1363 subjects. The severity of CV loss was measured in each subject and statistical, pass/fail outcomes established for each of the most commonly used, conventional colour assessment tests and protocols. This evidence and new findings that relate severity of loss to the effective use of colour signals in a number of tasks provide the basis for a new colour grading system based on six categories. A single colour assessment test is needed to establish the applicant's CV category which can range from 'supernormal', for the most stringent, colour-demanding tasks, to 'severe colour deficiency', when red/ green CV is either absent or extremely weak.

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Effective contrast of colored stimuli in the mesopic range: a metric for perceived contrast based on achromatic luminance contrast

Cited by 26 publications

References 38 publications

Effect of rod–cone interactions on mesopic visual performance mediated by chromatic and luminance pathways

Effect of rod–cone interactions on mesopic visual performance mediated by chromatic and luminance pathways

Changes in induced hues at low luminance and following dark adaptation suggest rod-cone interactions may differ for luminance increments and decrements

Colour vision requirements in visually demanding occupations

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