Illusion of brightness or lightness

Professor Alan Gilchrist's talk
in Ritsumeikan (March 17, 2006) Program

Opening talk (16:00-16:30)
　　　　"Ilusions of brightness or lightness"
Akiyoshi Kitaoka, Associate professor Ph.D (Ritsumeikan University, Dept. of Psychology)

since March 16, 2006 (7 digits since January 15, 2013)

Welcome!

Contents

Part 1. Illusory staircase Gelb effect: A new illusion

Part 2. Luminous fields appear darker than white ones

Soshi-kan and Mt. Kuniugasa-yama

Part 1. Illusory staircase Gelb effect: A new illusion

(1) Illusory staircase Gelb effect

The highest lightness rule is necessary, not the highest luminance rule.

Basic illusion (Luminance-gradient-dependent lightness illusion)

(2) Illusory staircase reverse Gelb effect

The lowest lightness rule is necessary in this condition.

Is the "reverse Gelb effect" possible?

A white cardboard in front of intensely bright background might possibly appear to be black until inserting a darker one in the visual field (lowest luminance rule?).

Jump to Part 2

Luminance-gradient-dependent lightness illusion*

*The term "Luminance-gradient-dependent brightness contrast" is also possible.

The left square appears to be darker than the right one, though they are identical in luminance gradient.

produced by Akiyoshi .Kitaoka 2006 (March 16)

cf. Land, E. H. and McCann, J. J. (1971) Lightness and retinex theory. Journal of the Optical Society of America, 61, 1-11. <touched up April 9, 2006>

"Anatomy" of the luminance-gradient-dependent lightness illusion

produced by Akiyoshi .Kitaoka 2006 (March 16)

"Robot"

The left circle appears to be lighter than the right one, though they are identical in luminance.

"Ninja"

The lightness of both eyes appears to be different from each other, but they are of the same luminance.

"Adelson's checker-shadow illusion-like gradation lightness illusion"

Physically, C = D !

cf. Adelson's checker-shadow illusion

Intrinsic model of the luminance-gradient-dependent lightness illusion

In this model, the luminance profile is explained as the summation or multiplication of illuminantion and surface reflectance.

produced by Akiyoshi .Kitaoka 2006 (March 16) (corrected Jnuary 11, 2017)

(original, wrong version)

The intrinsic model fails

If squares are placed separately, each square appears to be white. The leftmost one appears to be a white square with reduced pronounceness behind some "white mist".

produced by Akiyoshi .Kitaoka 2006 (March 16)

It is suggested that information of perceived luminance or brightness should also be taken into account.

Jump back to the title of this part to see the "illusory staircase reverse Gelb effect"

Part 2. Luminous fields appear darker than white ones

Question: Are luminous fields really brighter than white parts?

Answer: In the real environment "Yes", while in pictures or drawn images "No".

"Sea urchins"

Sea urchins appear to shed light.

"The sun"

The sun appears to expand.

Illusion therapy 2

Counterphase brightness induction

The left bar appears to be darker than the right bar in each image.

The luminous bar (top left) appears to be darker (if observerd locally) than the white bar (top right).

My speculation is that the highest luminance rule ignores the field that gives luminous appearance.

"Light of cubes"

There are glaring white diamonds and no-glare one, though they are identical in luminance. Moreover, the former appears to be darker than the latter when observers compare them in an analytical manner.

Visual phantoms

White diamonds are identical within the left image, though they appear to be different. Gray diamonds are identical in the right image, though they appear to be different (Logvinenko illusion).

produced by Akiyoshi .Kitaoka 2006 (March 16)

Logvinenko illusion

Although gray diamonds are identical, there appear to be light-gray ones and dark-gray ones.

Logvinenko, A. D. (1999) Lightness induction revisited. Perception, 28, 803-816.

One of Adelson's illusions

Although gray diamonds are identical, there appear to be light-gray ones and dark-gray ones.

Adelson, E. H. (1993) Perceptual organization and the judgment of brightness. Science, 262, 2042-2044..

Adelson, E. H. (2000) Lightness perception and lightness illusions. In M. Gazzaniga (Ed.), The New Cognitive Neurosciences, 2nd ed. Cambridge, MA: MIT Press. (pp. 339-351)

One of Gilchrist's illusions

Articulated surrounds enhance simultanous brightness contrast. The inner square in the left image appears to be lighter than the one in the right image.

Gilchrist, A., Kossyfidis, C., Bonato, F., Agostini, T., Cataliotti, J., Li, X., Spehar, B., Annan, V., and Economou, E. (1999) An anchoring theory of lightness perception. Psychological Review, 106, 795-834.

Gilchrist, A. and Annan, V. Jr. (2002) Articulation effects in lightness:Historical background and theoretical implications. Perception, 31, 141-150.

One of my lecture pages demonstrating this illusion (in Japanese)

Thank you

Akiyoshi's illusion pages