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Perceived contrast on displays with different luminance ranges
Patrik Sund1,2
1Department of Medical Physics and Biomedical Engineering, Sahlgrenska University Hospital, Göteborg, Sweden.
Medical Physics
|February 4, 2022
Summary
Medical display contrast perception is minimally affected by lighting conditions, suggesting current guidelines may be too restrictive. High luminance settings can maintain image quality, even in brighter environments.
Area of Science:
- Medical Imaging
- Human Visual Perception
- Display Technology
Background:
- Medical displays are crucial for healthcare, linking digital data to clinicians.
- Effective information transfer relies on optimal contrast perception.
- Evolving display technologies may exceed current medical display guidelines.
Purpose of the Study:
- To investigate contrast perception limits across diverse lighting conditions.
- To evaluate current medical display guidelines against empirical findings.
- To determine the impact of display luminance on perceived image quality.
Main Methods:
- Three display luminance settings (1-250, 6-500, 12-750 cd/m²) were tested.
- Contrast thresholds were measured using a two-alternative forced-choice method.
- Bar patterns at different spatial frequencies and pixel values were used across lighting conditions.
Main Results:
- Low-frequency patterns showed consistent contrast thresholds (≈0.5 JNDs) across all luminance settings.
- High-frequency patterns required significantly higher contrast, with worst visibility at the lowest luminance setting (1-250 cd/m²).
- Differences between luminance conditions were generally minor.
Conclusions:
- Medical displays with lower luminance ratios and higher minimum luminance can be viable.
- The number of just noticeable differences (JNDs) is a reliable metric for perceived contrast.
- Low luminance levels can impair visibility, particularly for fine details; avoidance is recommended.
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