Lightness and Retinex Theory

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Lightness and Retinex Theory

• Journal of the
• Optical Society of America
• Vol. 61, No. 1 Jan. 1971
• Edwin H. Land John J. McCann

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Outline

• Introduction
• Independence of Color
• Edges
• Entire Field of View
• Physical Model
• The Colored Mondrian
• Conclusion

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Outline

• Introduction
• Independence of Color
• Edges
• Entire Field of View
• Physical Model
• The Colored Mondrian
• Conclusion

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Introduction

• Reflectance(light or dark)
• Color(long-wave, middle-wave, and short-wave)
• Color sensation(the world the field of view)
• Departure(for exampleinsert a comparison
  standard)
• The light(the reflectance and illuminance)

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Outline

• Introduction
• Independence of Color
• Edges
• Entire Field of View
• Physical Model
• The Colored Mondrian
• Conclusion

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Independence of Color

• The Mondrian(avoid superposion)
• Refelctanceminimum 10
• Illuminated by three projectors
• 1. minimize the diversity
• when only projector turns on
• 2. a wider band more light

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Independence of Color

• Sharp-cut bandpass filter
• White rectangle(L, M, S 6, 35, 60)

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Independence of Color

• The dark brown area
• The areasbright yellow, blue, gray, lime green,
  and red
• The areas after readjusted illuminationyellow,
  blue, gray, green, and red
• Color sensation related the light(wavelength and
  luminance of any point)

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Independence of Color

• Wearing the gogglesdeep-red, dark-adaptation
  filter two eyes and only one eye
• The reports were almost the same as the previous
  results.
• Few changed the color name.
• Retinex retina cortex
• 3 lightness vs. 3 retinexs(L, M, S)

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Outline

• Introduction
• Independence of Color
• Edges
• Entire Field of View
• Physical Model
• The Colored Mondrian
• Conclusion

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Edges

• Reflected luminance
• 40 80

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Edges

• Place a pencil over the boundary between the two
  gray areas.

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Outline

• Introduction
• Independence of Color
• Edges
• Entire Field of View
• Physical Model
• The Colored Mondrian
• Conclusion

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Entire Field of View

• The ratio of reflectances

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Entire Field of View

• Luminance

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Outline

• Introduction
• Independence of Color
• Edges
• Entire Field of View
• Physical Model
• The Colored Mondrian
• Conclusion

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Physical Model

• Luminance

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Outline

• Introduction
• Independence of Color
• Edges
• Entire Field of View
• Physical Model
• The Colored Mondrian
• Conclusion

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The Colored Mondrian

• Retinex theory3 retinexs
• Each retinex served by one set of cones

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The Colored Mondrian

• The black, white, and gray Mondrian
• the ratio of sequential products
• The colored Mondrian
• the ratio of the integrals
• the weighting factor of the wavelength

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Outline

• Introduction
• Independence of Color
• Edges
• Entire Field of View
• Physical Model
• The Colored Mondrian
• Conclusion

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Conclusion

• The difference
• The function of retinex theory is to tell how the
  eye can ascertain reflectance in a field in which
  the illumination is unknowable and the
  reflectance is unknown.