Anchording Theory of Lightness Perception

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Figure 3. ‘Reproduced from “Discusion” by Howe, 2001, Discussion. Perception, 30(8), p. 1023. Reproduced with permission

Howe (2001) suggested that four gray bars were same in real reflectance. In Figure 3a, the left gray bar was inside a black framework, so it appeared lighter than the left gray bar. However, nearly half of the participants (thirteen participants) perceived no difference between two gray bars in Figure 3b (Howe, 2001). ATLP was failed to explain this result.

Another problem about ATLP is this theory based on the Gelb effect. Although the Gelb effect worked well on a surface like paper, this rule cannot apply to surface with a complex structure. As Sharan, Li, Motoyoshi, Nishida & Adelson (2008) showed in Figure 4, although two surfaces have the same background and apply same light, the right surface perceived lighter than the right one. [pic 4]

Figure 5. ‘Reproduced from “Image statistics for surface reflectance perception” by Sharan, Li, Motoyoshi, Nishida & Adelson, 2008, Image statistics for surface reflectance perception. JOSA A, 25(4), p. 847. Reproduced with permission

Finally, ALTP also failed to deal with the curvature of a surface. One limitation about previous researchers is that few people attempt to explore the relationship between curved surface and ALTP. Knill and Kersten (1991) settled two identical cylinders as showed in Figure 4. The only difference between two cylinders is their curvature. It is easy to perceived that the cylinder in left showed higher luminance than right one. However, it is impossible to explain this phenomenon by ALTP.

CONCLUSION

ALTP can be used to calculate the reflectance of a target surface and help us understand the light perception ability of human. It could further explain the Gelb effect (Cataliotti and Gilchrist, 1995). However, this theory still lacks the ability to solve the problem raised by Howe (2001), Knill and Kersten (1991), and Sharan, Li, Motoyoshi, Nishida & Adelson (2008). It is important to extend ALTP from identical surface to wild-range of the surface because human actually perceived different kinds of objects every day.

In future research, ALTP might be able to extend to more complex surface. Take the example from Sharan, Li, Motoyoshi, Nishida & Adelson (2008), the ALTP failed because the texture of surface. Could it because the shadow and spotlight in the surface divided the surface into more independent frameworks? If we could repeat this study and find a way to identify all frameworks separate across the complex surface, is it possible to apply the ALTP formula to those kinds of surface?

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Reference

Adelson, E. H. (2000). Zj^±Lightness Perception and Lightness Illusions. New Cogn. Neurosci, 339.

Cataliotti, J., & Gilchrist, A. (1995). Local and global processes in surface lightness perception. Attention, Perception, & Psychophysics, 57(2), 125-135.

Gelb, A. (1929). Die „Farbenkonstanz “der Sehdinge. In Handbuch der normalen und pathologischen Physiologie (pp. 594-678). Springer Berlin Heidelberg.

Gilchrist, A. L. (1977). Perceived lightness depends on perceived spatial arrangement. Science, 195(4274), 185-187.

Gilchrist, A., Kossyfidis, C., Bonato, F., Agostini, T., Cataliotti, J., Li, X. & Economou, E. (1999). An anchoring theory of lightness perception. Psychological review, 106(4), 795.

Gilchrist, A., & Cataliotti, J. (1994, March). Anchoring of surface lightness with multiple illumination levels. In Investigative Ophthalmology & Visual Science (Vol. 35, No. 4, pp. 2165-2165). 227 EAST WASHINGTON SQ, PHILADELPHIA, PA 19106: LIPPINCOTT-RAVEN PUBL.

Howe, P. D. (2001). Discussion. Perception, 30(8), 1023-1026.

Knill, D. C., & Kersten, D. (1991). Apparent surface curvature affects lightness perception. Nature, 351(6323), 228.

Li, X., & Gilchrist, A. L. (1999). Relative area and relative luminance combine to anchor surface lightness values. Perception & Psychophysics, 61(5), 771-785.

Sharan, L., Li, Y., Motoyoshi, I., Nishida, S. Y., & Adelson, E. H. (2008). Image statistics for surface reflectance perception. JOSA A, 25(4), 846-865.