Simulation of Artificial Vision, III: Do the Spatial or Temporal Characteristics of Stimulus Pixelization Really Matter?

Fornos, Ange ́lica Pe ́rez; Sommerhalder, J.; Rappaz, Benjamin; Safran, Avinoam B.; Pelizzone, M.

doi:10.1167/iovs.04-1173

Cited by 70 publications

(57 citation statements)

References 34 publications

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“…Thompson et al (2003) investigated the minimum requirements for face recognition and Fornos et al (2005) used a visual prosthesis simulator to compare the scanning benefit and shape of individual pixels, square vs. Gaussian, in enabling reading. Hallum et al (2005) explored the effect of pixelized vision on various eye movements, i.e.…”

Section: Introductionmentioning

confidence: 99%

Assessing the utility of visual acuity measures in visual prostheses

Caspi

Zivotofsky

2015

Vision Research

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There are presently several ongoing clinical trials to provide usable sight to profoundly visually impaired patients by means of electrical stimulation of the retina. Some of the blind patients implanted with retinal prosthesis reported un-patterned perception and yet benefit from the device in many activities of daily living, seemingly because they adopt active scanning strategies. The aim of the present work is to evaluate if and under what conditions a measured visual acuity level is truly an indication that the brain perceived a patterned image from the electrical stimulation of the visual prosthesis. Sighted subjects used a pixelized simulator in which they perceived either a low resolution sub-sampling of the original image ("normal mode"--patterned vision) or an image that was solely a function of the brightness and size of the original image ("brightness mode"--no patterned vision). Results show that subjects were able to adopt a head scanning strategy that enabled acuity beyond the resolution set by a static view of the stimulus. In brightness mode, i.e. without patterned vision, most subjects achieved a measurable acuity level better than the limit set by the geometrical resolution of the entire array but worse than the limit set by the distance between neighboring simulated pixels. In normal mode all subject achieved acuity level that is better than the geometrical resolution of the simulated pixels. Thus, visual acuity levels comparable with the electrodes/pixels resolution implies that the patient perceives an image with spatial patterns.

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Section: Introductionmentioning

confidence: 99%

Assessing the utility of visual acuity measures in visual prostheses

Caspi

Zivotofsky

2015

Vision Research

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“…Inspiring results were reported 0020-0255/$ -see front matter Ó 2010 Elsevier Inc. All rights reserved. doi:10.1016/j.ins.2010.04.021 on Latin word recognition [24,25,34], Chinese character recognition [8], reading speed [5][6][7], text or paragraph reading [35,15,10], maze navigation [6], object recognition [19], hand-eye coordination [19], way finding [11], etc. However, it is important to confirm the minimum requirements for visual prostheses through different experiments.…”

Section: Introductionmentioning

confidence: 99%

Image processing based recognition of images with a limited number of pixels using simulated prosthetic vision

Zhao

Lü

Tian

et al. 2010

Information Sciences

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“…There is a growing body of literature concerning the phosphene image and perception (e.g., [8], [9], [10]). These studies have involved the recognition of (phosphenized) faces, reading speeds of (phosphenized) text, and the acuity that the phosphene image affords observers.…”

Section: Discussionmentioning

confidence: 99%

Psychophysics of Prosthetic Vision: II. Stochastic Sampling, the Phosphene Image, and Noise

Hallum¹,

Chen²,

Cloherty³

et al. 2006

2006 International Conference of the IEEE Engineering in Medicine and Biology Society

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Stimulation of the diseased retina via an intraocular electrode array is a proposed means of restoring some vision to the profoundly blind. A prosthetic device to this end would involve post-implantation calibration (analogous to cochlear implant fitting), wherein the subject indicates those discrete positions in the visual field where luminous percepts are elicited. This procedure would be a source of noise, because the indicated positions would only approximate the actual positions in the visual field. Put differently, the procedure introduces sampling jitter, and would therefore affect clinical outcomes such as mobility and reading speeds. The nature of this noise is the concern of the present paper; we derive an expression for the noise power spectrum as it relates to the statistical nature of the sampling jitter. We show that, generally, jitter has greater effect on higher spatial-frequencies, that is, those areas of the implantee's visual perception that represent fine detail are more prone to noise. More specifically, the noise spectrum depends on the characteristic function of the random variable describing the sampling jitter. Our results signal the need for experimental work that characterizes sampling jitter in implantees, plus the need for simulations that allow a better understanding of perception and the noisy phosphene image.

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Simulation of Artificial Vision, III: Do the Spatial or Temporal Characteristics of Stimulus Pixelization Really Matter?

Abstract: This study reveals that real-time stimulus pixelization favors reading performance. Performance gains were moderate, however, and did not allow for a significant (e.g., twofold) reduction of the minimum resolution (400-500 pixels) needed to achieve useful reading abilities.

Cited by 70 publications

References 34 publications

Assessing the utility of visual acuity measures in visual prostheses

Assessing the utility of visual acuity measures in visual prostheses

Image processing based recognition of images with a limited number of pixels using simulated prosthetic vision

Psychophysics of Prosthetic Vision: II. Stochastic Sampling, the Phosphene Image, and Noise

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