Visual discomfort and blur

Abstract

Certain visual stimuli, such as striped patterns and filtered noise, have been reported to be uncomfortable. Some filtered noise patterns judged as uncomfortable are those with a relative decrease in contrast amplitude at high spatial frequencies, compared with the statistics typical of natural images. Decreased amplitude at high spatial frequencies is a characteristic often associated with perceived blur. Additionally, the distribution of contrast across spatial frequencies also provides a cue for the accommodation (focusing) response. The purpose of this study was to investigate the relationship between excess low spatial frequency information, discomfort judgments and perceived blur. Results of these experiments show that a relative reduction in high spatial frequency contrast results in both increased discomfort and perceived blur. This is both in artificial and natural stimuli. A possible explanation for this relationship based on accommodation responses is proposed.

Visual discomfort and flicker

“…To explore purely temporal variations, we measured discomfort for uniform fields flickered with different phase and amplitude spectra, using a two-alternative forced-choice (2AFC) task. The 2AFC method is suitable for an assessment of relative discomfort or pleasantness of viewing (O’Hare and Hibbard, 2013). In the spatial domain, both relative pleasantness in 2AFC and rated pleasantness on a Likert scale were directly compared as a function of spatial frequency, thereby revealing that the results were closely comparable and related to perceptual distortions, headaches, and discomfort (Wilkins et al, 1984).…”

“…In the spatial domain, there is a burgeoning literature on visual discomfort, which is closely allied to photophobia, and exacerbated in migraine: striped patterns (Chatrian et al, 1970; Marcus and Soso, 1989; Wilkins et al, 1984; Wilkins 1995), filtered noise (Fernandez and Wilkins, 2008; Juricevic et al, 2010; O’Hare and Hibbard, 2011), blurred images (O’Hare and Hibbard, 2013), certain artistic styles (Fernandez and Wilkins, 2008), and images comprising clusters of objects (Cole and Wilkins, 2013) have all been reported to produce seizures, discomfort or aversion. Discomfort from images could arise from many sources, including properties of the stimulus (e.g., gloomy illumination or glare) or properties of the observer (e.g., accommodative stress or lag, photophobia, or cognitive factors).…”

Gaze-contingent depth of field in realistic scenes

“…The short-term and long-term effects of visual stress on visual discomfort and visual fatigue are not always distinguished. Many studies present images to the subjects for several seconds (0.5 to 15 s is typical) and have them judge or compare the images in terms of viewing comfort [Blum et al, 2010;Kooi & Toet, 2004;O'Hare & Hibbard, 2013]. To study visual fatigue extended exposures are needed to see how the visual system responds to the potential visual stress [Hoffman et al, 2008;Mon-Williams & Wann, 1998;Ukai & Howarth, 2008].…”

“…It is possible that the short-exposure and long-exposure effects differ because image blur has been associated with immediate visual discomfort [O'Hare & Hibbard, 2013] while appropriate optical blur in a display reduces visual fatigue by reducing acommodative-vergence conflict [Hoffman et al, 2008]. We are conducting experiments with extended viewing to assess the effects of dynamic DOF cues on visual fatigue.…”

“…Theoretically, if simulated depth of field matched a natural depth of field, the simulation should be indistinguishable from a real scene (in terms of image sharpness). Dispite our best effort to minimize latency of the system, in some cases, the change in focus was still noticed by participants and it unfortunately reduced the comfort [Kooi and Toet 2004;O'Hare and Hibbard 2013]. Kooi and Toet [2004] showed noticeable imperfections in stereoscopic image can be described as very uncomfortable for an observer.…”