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Contrast (vision)

About: Contrast (vision) is a research topic. Over the lifetime, 10379 publications have been published within this topic receiving 221480 citations.


Papers
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Journal ArticleDOI
TL;DR: The proposed metric is particularly effective to visual signal with blurring and luminance fluctuations as the major artifacts, and brings about the fundamental improvement when sharpened image edges are involved.
Abstract: This paper presents a method to discriminate pixel differences according to their impact toward perceived visual quality. Noticeable local contrast changes are formulated firstly since contrast is the basic sensory feature in the human visual system (HVS) perception. The analysis aims at quantifying the actual impact of such changes (further divided into increases and decreases on edges) in different signal contexts. An associated full-reference distortion metric proposed next provides better match with the HVS viewing. Experiments have used two independent visual data sets and the related subjective viewing results, and demonstrated the performance improvement of the proposed metric over the relevant existing ones with various video/images and under diversified test conditions. The proposed metric is particularly effective to visual signal with blurring and luminance fluctuations as the major artifacts, and brings about the fundamental improvement when sharpened image edges are involved.

105 citations

BookDOI
01 Jan 2009
TL;DR: A.L. Gilchrist, Absolute Versus Relative Theories of Lightness Perception as mentioned in this paper, The Psychophysics of Contrast Brightness, and Contrasting Brightness and Ordinary Seeing.
Abstract: Contents: A.L. Gilchrist, Absolute Versus Relative Theories of Lightness Perception. P. Whittle, The Psychophysics of Contrast Brightness. P. Whittle, Contrast Brightness and Ordinary Seeing. L. Arend, Surface Colors, Illumination, and Surface Geometry: Intrinsic-Image Models of Human Color Perception. W. Gerbino, Achromatic Transparency. S.S. Bergstrom, Color Constancy: Arguments for a Vector Model for the Perception of Illumination, Color, and Depth.

105 citations

Journal ArticleDOI
TL;DR: Although Z40 was significantly lower in the eyes with the aspherical IOL, no statistically significant differences were found between asphericals and spherical IOLs in LCVA, HCVA, and contrast sensitivity.
Abstract: Purpose To intraindividually compare visual performance in terms of photopic high-contrast visual acuity (HCVA), mesopic HCVA, mesopic low-contrast visual acuity (LCVA), and contrast sensitivity (CS) in patients after implantation of either an aspherical or a spherical intraocular lens (IOL). Setting Department of Ophthalmology, Johann Wolfgang Goethe-University, Frankfurt am Main, Germany. Methods Forty eyes of 20 patients were randomized to implantation of an aspherical IOL (Tecnis Z9000, AMO) in 1 eye and a spherical IOL (Sensar AR40e, AMO) in the other eye. Three to 4 months postoperatively, photopic HCVA (270 cd/m 2 ) was measured with the observer-independent Frankfurt-Freiburg Contrast and Acuity Test System (FF-CATS) and high-mesopic HCVA and LCVA (8 cd/m 2 ) were measured with Early Treatment Diabetic Retinopathy Study charts. CS was assessed with the FF-CATS under photopic (167 cd/m 2 ), high-mesopic (1.67 cd/m 2 ), and low-mesopic (0.167 cd/m 2 ) luminance conditions with and without glare. For each individual eye, higher-order wavefront aberrations were reconstructed for a physiological mesopic pupil diameter. Intraindividual differences (Δ i ) in visual acuity, contrast sensitivity, and higher-order aberrations (HOAs) were calculated, and the influence of age and Δ i HOA on Δ i contrast sensitivity (logCS) under high-mesopic conditions was investigated using multiple regression analysis. Results There were no statistically significant differences between the Tecnis IOL and the Sensar IOL in visual acuity measurements or contrast sensitivity measurements. For physiological mesopic pupil diameter, primary spherical aberration (Z 4 0 ) was significantly lower in the Tecnis group ( P 4 0 , the Δ i values were distributed around zero. Multiple regression analysis showed only a partial influence of Δ i Z 4 0 on Δ i logCS (adjusted R 2 = 0.49) but did not show any influence of age, coma-like aberration, or residual HOA. Conclusions Although Z 4 0 was significantly lower in the eyes with the aspherical IOL, no statistically significant differences were found between aspherical and spherical IOLs in LCVA, HCVA, and contrast sensitivity. Statistical analysis of intraindividual contrast sensitivity differences showed that in most patients, this Z 4 0 difference was too low to have an effect on contrast sensitivity.

104 citations

Journal ArticleDOI
TL;DR: Patients with relatively well conserved visual acuity showed a marked impairment in contrast sensitivity for targets of high and intermediate spatial frequencies, while patients with more advanced disease showed a pronounced impairment across a larger spectrum of frequencies.
Abstract: Psychophysical measurements of contrast thresholds for sinusoidal gratings of variable frequency were made in normal controls and in patients with macular disease. Normal controls showed a U-shaped contrast sensitivity function comparable with previous reports. Patients with relatively well conserved visual acuity showed a marked impairment in contrast sensitivity for targets of high and intermediate spatial frequencies, while patients with more advanced disease showed a pronounced impairment across a larger spectrum of frequencies. Our findings provide insight into the visual difficulties of daily life of patients with macular disease. The determination of contrast sensitivity seems to be an important and very sensitive tool for the detection of early disturbances.

104 citations

Journal Article
TL;DR: The results show that the transient VER consists of a relatively simple waveform that is most easily characterized by the initial negative peak (N1) whose latency and amplitude vary with the contrast and spatial frequency of the grating.
Abstract: Transient visual evoked responses (VER's) to the appearance-disappearance of sinusoidal gratings have been investigated for a range of spatial frequencies Contrary to the results of previous studies, the results show that the transient VER consists of a relatively simple waveform that is most easily characterized by the initial negative peak (N1) whose latency and amplitude vary with the contrast and spatial frequency of the grating At spatial frequencies less than 3 cycles/degree (c/d) an additional short latency component appears in the response This component is maximum at 1 to 2 c/d, saturates at low contrast, and is insensitive to the precise position of the grating on the retina The results are related to the properties of transient and sustained channels assumed to exist in the human visual system

104 citations


Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20241
20231,864
20223,760
2021413
2020329
2019354