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 Contrast Sensitivity Functions for HDR Displays

2020 ◽  
Vol 2020 (1) ◽  
pp. 44-48
Author(s):  
Minjung Kim ◽  
Maliha Ashraf ◽  
María Pérez-Ortiz ◽  
Jasna Martinovic ◽  
Sophie Wuerger ◽  
...  
Keyword(s):  
Contrast Sensitivity ◽  
Dynamic Range ◽  
High Dynamic Range ◽  
Background Luminance ◽  
Monotonic Functions ◽  
Sensitivity Functions ◽  
Spatial Frequencies ◽  
Peak Sensitivity ◽  
Achromatic Contrast ◽  
High Dynamic

Contrast sensitivity functions (CSFs) characterize the sensitivity of the human visual system at different spatial frequencies. However, little is known about CSFs at luminances above 1000 cd/m2, especially for color. Here, we measured contrast sensitivities at background luminances from 0.02 cd/m2 to 7000 cd/m2 and for three color directions (black-white or achromatic, red-green, and yellow-violet). Stimuli were Gabor patches of various spatial frequencies (0.125 to 6 cpd), displayed on a custom-built high dynamic range display (peak luminance: 15,000 cd/m2). We found that achromatic contrast sensitivity has an inverted U-shape as a function of background luminance, with peak sensitivity at 200 cd/m2, while red-green and yellow-violet contrast sensitivities were monotonic functions of background luminance, saturating at 200 cd/m2. Based on these measurements, we developed a model that predicts contrast sensitivity for the average observer. This model is intended for applications in high dynamic range imaging.

A Comparative Study of the Spatial-Frequency Spectrum of Different Letter Optotypes and its Role in Target Recognition

Perception ◽  
1997 ◽  
Vol 26 (1_suppl) ◽  
pp. 214-214 ◽  
Author(s):  
S A Koskin ◽  
V F Danilichev ◽  
Y E Shelepin
Keyword(s):  
Spatial Frequency ◽  
Contrast Sensitivity ◽  
Frequency Spectrum ◽  
Brain Diseases ◽  
Sinusoidal Grating ◽  
Sensitivity Functions ◽  
Spatial Frequencies ◽  
Wide Range ◽  
Narrow Frequency Band ◽  
Spatial Frequency Spectrum

We studied the contrast sensitivity functions (CSFs) in patients with different eye and brain diseases using a computerised sinusoidal grating test with a wide range of frequencies (0.4 – 19.0 cycles deg−1), the Pelli - Robson chart and a new chart with frequency-filtered Snellen optotypes. The patients had different CSF curves with a decrease of contrast sensitivity in the low, middle, or high frequencies depending on their main disease (refraction anomalies, cataract, glaucoma, neuritis of optic nerve, brain tumours, etc). Analysis showed that optotypes in the Pelli - Robson chart have a wide-range spatial-frequency spectrum, and optotype recognition is determined not only by low spatial frequencies. We find that the recognition of standard Sloan's optotypes is determined mostly by sensitivity in the range of 9.4 – 14.0 cycles deg−1. At the same time we measured contrast sensitivity using the new filtered Snellen optotypes. Our calculations support our earlier suggestions that the new filtered optotypes have a narrow-band spatial-frequency spectrum, thus enabling selective measurement of contrast sensitivity in each narrow frequency band.

scholarly journals Perceptually motivated model for predicting banding artefacts in high-dynamic range images

2020 ◽  
Vol 2020 (28) ◽  
pp. 42-48
Author(s):  
Minjung Kim ◽  
Maryam Azimi ◽  
Rafał K. Mantiuk
Keyword(s):  
Visual System ◽  
Contrast Sensitivity ◽  
Dynamic Range ◽  
High Dynamic Range ◽  
Sensitivity Function ◽  
Psychophysical Experiment ◽  
Texture Region ◽  
Wide Range ◽  
Artefact Detection ◽  
High Dynamic

Banding is a type of quantisation artefact that appears when a low-texture region of an image is coded with insufficient bitdepth. Banding artefacts are well-studied for standard dynamic range (SDR), but are not well-understood for high dynamic range (HDR). To address this issue, we conducted a psychophysical experiment to characterise how well human observers see banding artefacts across a wide range of luminances (0.1 cd/m2–10,000 cd/m2). The stimuli were gradients modulated along three colour directions: black-white, red-green, and yellow-violet. The visibility threshold for banding artefacts was the highest at 0.1 cd/m2, decreased with increasing luminance up to 100 cd/m2, then remained at the same level up to 10,000 cd/m2. We used the results to develop and validate a model of banding artefact detection. The model relies on the contrast sensitivity function (CSF) of the visual system, and hence, predicts the visibility of banding artefacts in a perceptually accurate way.

Product Review: High Dynamic Range Displays

2007 ◽  
Vol 16 (1) ◽  
pp. 119-122 ◽  
Author(s):  
Patrick Ledda
Keyword(s):  
Dynamic Range ◽  
Liquid Crystal Display ◽  
Contrast Ratio ◽  
Luminance Level ◽  
High Dynamic Range ◽  
Natural World ◽  
Adaptation Level ◽  
Wide Range ◽  
High Dynamic ◽  
3D Software

In the natural world, the human eye is confronted with a wide range of colors and luminances. A surface lit by moonlight might have a luminance level of around 10−3 cd/m2, while surfaces lit during a sunny day could reach values larger than 105 cd/m2. A good quality CRT (cathode ray tube) or LCD (liquid crystal display) monitor is only able to achieve a maximum luminance of around 200 to 300 cd/m2 and a contrast ratio of not more than two orders of magnitude. In this context the contrast ratio or dynamic range is defined as the ratio of the highest to the lowest luminance. We call high dynamic range (HDR) images, those images (or scenes) in which the contrast ratio is larger than what a display can reproduce. In practice, any scene that contains some sort of light source and shadows is HDR. The main problem with HDR images is that they cannot be displayed, therefore although methods to create them do exist (by taking multiple photographs at different exposure times or using computer graphics 3D software for example) it is not possible to see both bright and dark areas simultaneously. (See Figure 1.) There is data that suggests that our eyes can see detail at any given adaptation level within a contrast of 10,000:1 between the brightest and darkest regions of a scene. Therefore an ideal display should be able to reproduce this range. In this review, we present two high dynamic range displays developed by Brightside Technologies (formerly Sunnybrook Technologies) which are capable, for the first time, of linearly displaying high contrast images. These displays are of great use for both researchers in the vision/graphics/VR/medical fields as well as professionals in the VFX/gaming/architectural industry.

Visual Contrast Sensitivity Functions Obtained with Colored and Achromatic Gratings

1979 ◽  
Vol 21 (2) ◽  
pp. 225-228 ◽  
Author(s):  
Michael A. Nelson ◽  
Ronald L. Halberg
Keyword(s):  
Contrast Sensitivity ◽  
Spatial Information ◽  
Sensitivity Functions ◽  
Visual Contrast ◽  
Spatial Frequencies ◽  
Sinusoidal Gratings ◽  
Visual Contrast Sensitivity ◽  
Contrast Thresholds

Threshold contrasts for red, green, and achromatic sinusoidal gratings were measured. Spatial frequencies ranged from 0.25 to 15 cycles/deg. No significant differences in contrast thresholds were found among the three grating types. From this finding it was concluded that, under conditions of normal viewing, no significant differences should be expected in the acquisition of spatial information from monochromatic or achromatic displays of equal resolution.

Using ACES Look Modification Transforms (LMTs) in VFX Environments – Part 2: Gamut Mapping

2021 ◽  
Vol 2021 (3) ◽  
pp. 108-1-108-14
Author(s):  
Eberhard Hasche ◽  
Oliver Karaschewski ◽  
Reiner Creutzburg
Keyword(s):  
Dynamic Range ◽  
List Item ◽  
Color Space ◽  
High Dynamic Range ◽  
Target Color ◽  
List Type ◽  
Color Spaces ◽  
Gamut Mapping ◽  
Scale Down ◽  
Image Production

In modern moving image production pipelines, it is unavoidable to move the footage through different color spaces. Unfortunately, these color spaces exhibit color gamuts of various sizes. The most common problem is converting the cameras’ widegamut color spaces to the smaller gamuts of the display devices (cinema projector, broadcast monitor, computer display). So it is necessary to scale down the scene-referred footage to the gamut of the display using tone mapping functions [34].In a cinema production pipeline, ACES is widely used as the predominant color system. The all-color compassing ACES AP0 primaries are defined inside the system in a general way. However, when implementing visual effects and performing a color grade, the more usable ACES AP1 primaries are in use. When recording highly saturated bright colors, color values are often outside the target color space. This results in negative color values, which are hard to address inside a color pipeline. "Users of ACES are experiencing problems with clipping of colors and the resulting artifacts (loss of texture, intensification of color fringes). This clipping occurs at two stages in the pipeline: <list list-type="simple"> <list-item>- Conversion from camera raw RGB or from the manufacturer’s encoding space into ACES AP0</list-item> <list-item>- Conversion from ACES AP0 into the working color space ACES AP1" [1]</list-item> </list>The ACES community established a Gamut Mapping Virtual Working Group (VWG) to address these problems. The group’s scope is to propose a suitable gamut mapping/compression algorithm. This algorithm should perform well with wide-gamut, high dynamic range, scene-referred content. Furthermore, it should also be robust and invertible. This paper tests the behavior of the published GamutCompressor when applied to in- and out-ofgamut imagery and provides suggestions for application implementation. The tests are executed in The Foundry’s Nuke [2].

Acuity-sensitivity trade-offs of X and Y cells in the cat lateral geniculate complex: role of the medial interlaminar nucleus in scotopic vision

1992 ◽  
Vol 68 (4) ◽  
pp. 1235-1247 ◽  
Author(s):  
D. Lee ◽  
C. Lee ◽  
J. G. Malpeli
Keyword(s):  
Contrast Sensitivity ◽  
Adaptation Level ◽  
Special Role ◽  
A Cells ◽  
Lateral Geniculate ◽  
Spatial Frequencies ◽  
Wide Range ◽  
Sinusoidal Gratings ◽  
X Cells ◽  
Y Cells

1. The cat medial interlaminar nucleus (MIN) receives inputs almost exclusively from tapetal retina, suggesting that the MIN has a special role in dim-light vision. In this study we compared the sensitivities of cells in the MIN with those in layers A and magnocellular C of the lateral geniculate nucleus (LGNd), using drifting sinusoidal gratings to determine contrast thresholds as a function of spatial frequency and retinal adaptation level over the entire scotopic range. 2. About one-half of the cells recorded in the MIN and layer A had brisk responses that could be nulled by properly positioned, counterphased sinusoidal gratings, and were classified as X cells. The rest of the cells in the MIN and layer A, as well as all cells recorded in layer C, were Y cells. 3. MIN cells had higher contrast sensitivity than layer A cells for low spatial frequencies (0.15 cycles/deg and below) over a wide range of adaptation levels, both overall and for separate comparisons within X or Y cells. Layer C Y cells were intermediate in sensitivity between MIN and layer A Y cells. For low spatial frequencies, Y cells as a group were more sensitive than X cells, whereas the reverse was true for high spatial frequencies. 4. These data enable one to determine the lowest adaptation level at which stimuli of a given contrast can be detected for a given structure. At the lowest spatial frequencies, the MIN can function at adaptation levels approximately 1 log unit below layer A, averaged over all stimulus contrasts. In contrast, the tapetum lowers luminance threshold by at most 0.16 log unit. 5. For scotopic conditions and eccentricities within 15 degrees of the area centralis, contrast sensitivity decreases with eccentricity for low spatial frequencies and remains flat or slightly increases for high spatial frequencies. This relationship, which is opposite to that found for photopic vision, is strongest for MIN Y cells. 6. These data support the hypothesis that the retinal conflict between sensitivity and acuity is ameliorated in the CNS through separate thalamic relays with different degrees of afferent convergence. MIN cells have higher luminance sensitivity than layer A cells, but at the expense of acuity. Layer C appears to occupy an intermediate position in this trade-off.

Comparison of contrast sensitivity in macaque monkeys and humans

2019 ◽  
Vol 36 ◽  
Author(s):  
William H. Ridder ◽  
Kai Ming Zhang ◽  
Apoorva Karsolia ◽  
Michael Engles ◽  
James Burke
Keyword(s):  
Contrast Sensitivity ◽  
Macaca Mulatta ◽  
Macaca Fascicularis ◽  
Area Under The Curve ◽  
Macaca Nemestrina ◽  
Published Data ◽  
Sensitivity Functions ◽  
Spatial Frequencies ◽  
Double Exponential ◽  
Normal Humans

AbstractContrast sensitivity functions reveal information about a subject’s overall visual ability and have been investigated in several species of nonhuman primates (NHPs) with experimentally induced amblyopia and glaucoma. However, there are no published studies comparing contrast sensitivity functions across these species of normal NHPs. The purpose of this investigation was to compare contrast sensitivity across these primates to determine whether they are similar. Ten normal humans and eight normal NHPs (Macaca fascicularis) took part in this project. Previously published data from Macaca mulatta and Macaca nemestrina were also compared. Threshold was operationally defined as two misses in a row for a descending method of limits. A similar paradigm was used for the humans except that the descending method of limits was combined with a spatial, two-alternative forced choice (2-AFC) technique. The contrast sensitivity functions were fit with a double exponential function. The averaged peak contrast sensitivity, peak spatial frequency, acuity, and area under the curve for the humans were 268.9, 3.40 cpd, 27.3 cpd, and 2345.4 and for the Macaca fascicularis were 99.2, 3.93 cpd, 26.1 cpd, and 980.9. A two-sample t-test indicated that the peak contrast sensitivities (P = 0.001) and areas under the curve (P = 0.010) were significantly different. The peak spatial frequencies (P = 0.150) and the extrapolated visual acuities (P = 0.763) were not different. The contrast sensitivities for the Macaca fascicularis, Macaca mulatta, and Macaca nemestrina were qualitatively and quantitatively similar. The contrast sensitivity functions for the NHPs had lower peak contrast sensitivities and areas under the curve than the humans. Even though different methods have been used to measure contrast sensitivity in different species of NHP, the functions are similar. The contrast sensitivity differences and similarities between humans and NHPs need to be considered when using NHPs to study human disease.

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