Visual adaptation: softcopy image contribution to the observer's field of view

Toomey, Rachel, Curran, Kathleen, D'Helft, C., Joyce, Maria B., Stowe, John, Ryan, John, McEntee, Mark F., Manning, David and Brennan, Patrick (2008) Visual adaptation: softcopy image contribution to the observer's field of view. In: Sahina, Berkmann and Manning, David J, (eds.) Medical Imaging 2008: Image Perception, Observer Performance, and Technology Assessment (Proceedings Volume). SPIE, USA: Bellingham WA 98227-0010, 69170O-1. Full text not available from this repository.

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Abstract

Purpose: Detection of low-contrast details is highly dependent on the adaptation state of the eye. It is important therefore that the average luminance of the observer's field of view (FOV) matches those of softcopy radiological images. This study establishes the percentage of FOV filled by workstations at various viewing distances. Methods: Five observers stood at viewing distances of 20, 30 and 50cm from a homogenous white surface and were instructed to continuously focus on a fixed object at a height appropriate level. A dark indicator was held at this object and then moved steadily until the observer could no longer perceive it in his/her peripheral vision. This was performed at 0°, 90°, 180° and 270° clockwise from the median sagittal plane. Distances were recorded, radii calculated and observer and mean FOV areas established. These values were then compared with areas of typical high and low specification workstations. Results: Individual and mean FOVs were 7660, 15463 and 30075cm2 at viewing distances of 20, 30 and 50cm respectively. High and low specification monitors with respective areas of 1576.25 and 921.25cm2 contributed between 5 to 21% and 3 to 12% respectively to the total FOV depending on observer distance. Limited inter-observer variances were noted. Conclusions: Radiology workstations typically comprise between only 3 and 21% of the observer's FOV. This demonstrates the importance of measuring ambient light levels and surface reflection coefficients in order to maximise adaptation and observer's perception of low contrast detail and minimise eye strain.

Item Type: Book Section
Journal or Publication Title: Medical Imaging 2008: Image Perception, Observer Performance, and Technology Assessment (Proceedings Volume)
Publisher: SPIE
ISBN: 9780819471017
DOI: https://doi.org/10.1117/12.770305
Departments: Faculty of Health and Science > Medical and Sports Sciences > Health and Medical Sciences
Depositing User: Janet Henderson
Date Deposited: 25 Nov 2009 10:28
Last Modified: 26 Aug 2016 16:08
URI: http://insight.cumbria.ac.uk/id/eprint/32

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