Transcript Lightness and Retinex Theory

Lightness and Retinex Theory
Journal of the
Optical Society of America
Vol. 61, No. 1 Jan. 1971
Edwin H. Land & John J. McCann
Outline
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Introduction
Independence of Color
Edges
Entire Field of View
Physical Model
The Colored Mondrian
Conclusion
Outline
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Introduction
Independence of Color
Edges
Entire Field of View
Physical Model
The Colored Mondrian
Conclusion
Introduction
• Reflectance（light or dark）
• Color（long-wave, middle-wave, and
short-wave）
• Color sensation（the world & the field of
view）
• Departure（for example：insert a
comparison standard）
• The light（the reflectance and illuminance）
Outline
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Introduction
Independence of Color
Edges
Entire Field of View
Physical Model
The Colored Mondrian
Conclusion
Independence of Color
• The Mondrian（avoid superposion）
• Refelctance：minimum = 10%
• Illuminated by three projectors
1. minimize the diversity
when only projector turns on
2. a wider band & more light
Independence of Color
• Sharp-cut bandpass filter
• White rectangle（L, M, S ＝ 6, 35, 60）
Independence of Color
• The dark brown area
• The areas：bright yellow, blue, gray, lime
green, and red
• The areas after readjusted illumination：
yellow, blue, gray, green, and red
• Color sensation related the light
（wavelength and luminance of any point）
Independence of Color
• Wearing the goggles：deep-red, darkadaptation 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）
Outline
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Introduction
Independence of Color
Edges
Entire Field of View
Physical Model
The Colored Mondrian
Conclusion
Edges
• Reflected luminance
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40%
80%
Edges
• Place a pencil over the boundary between
the two gray areas.
Outline
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Introduction
Independence of Color
Edges
Entire Field of View
Physical Model
The Colored Mondrian
Conclusion
Entire Field of View
• The ratio of reflectances
Entire Field of View
• Luminance
Outline
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Introduction
Independence of Color
Edges
Entire Field of View
Physical Model
The Colored Mondrian
Conclusion
Physical Model
• Luminance
Outline
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Introduction
Independence of Color
Edges
Entire Field of View
Physical Model
The Colored Mondrian
Conclusion
The Colored Mondrian
• Retinex theory：3 retinexs
Each retinex served by one set of cones
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
Outline
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Introduction
Independence of Color
Edges
Entire Field of View
Physical Model
The Colored Mondrian
Conclusion
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.