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Vertical anisotropy in lightness perception not caused by lighting assumption
Yuki Kobayashi1, Kazunori Morikawa2
1Ritsumeikan University, Japan; Osaka University, Japan; Japan Society for the Promotion of Science, Japan.
Vision Research
|March 5, 2023
Summary
Visual perception of lightness is influenced by an illusory inversion effect. This study reveals that both low-level visual anisotropy and assumptions about lighting contribute to how we perceive image lightness.
Area of Science:
- Visual Perception
- Computational Neuroscience
- Image Processing
Background:
- An illusory inversion effect causes upward-facing gray panels to appear darker than downward-facing ones.
- This effect was previously attributed to an implicit assumption that light typically comes from above.
Purpose of the Study:
- To investigate the contribution of low-level visual anisotropy to the lightness inversion effect.
- To determine if visual anisotropy influences perceived lightness even without depth cues.
Main Methods:
- Experiments manipulated image position, contrast polarity, and edge presence.
- Stimuli without depth cues were used to isolate anisotropy effects.
- Simpler configurations were employed to confirm findings.
Main Results:
- Brighter upper edges consistently made targets appear lighter, supporting anisotropy's role.
- Low-level anisotropy contributes to the inversion effect, independent of depth information.
- Ambiguous results for darker upper edges suggest complex anisotropy interactions.
Conclusions:
- Both low-level vertical anisotropy and mid-level lighting assumptions significantly influence perceived lightness.
- Two types of vertical anisotropy may affect perceived lightness: one contrast-dependent, one independent.
- The findings integrate low-level visual processing with higher-level assumptions in lightness perception.
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