Cônes et bâtonnets. Sensibilité spectrale des photorécepteurs.
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Transcript of Cônes et bâtonnets. Sensibilité spectrale des photorécepteurs.
Cônes et bâtonnets
Sensibilité spectrale des photorécepteurs
Mélange soustractif des couleurs (pigments)
Mélange additif des couleurs (lumières)
Color matching
Trichromacy
Trichromacy (Young-Helmholtz)
• 3 primaires = blanc
• X = A + B+ C
• Télévision, imprimerie
Munsell system
Sensibilité spectrale des cônes
Figure 1. Spectral sensitivity of the S-cone, M-cone and L-cone. Combined results from various authors using different methods including retinal densitometry from Rushton ( and ), microspectrometry from Brown and Wald ( and “ ) and increment threshold producing artificial monochromasy from Brinley ( and ) and increment threshold measurements from Wald ( ) (From Moses, R. A. and Hart, W. M. (Ed) Adler's Physiology of the Eye, Clinical Application. St. Louis: The C. V. Mosby Company, 1987.(12 K jpeg image)
Champs de sensibilité aux couleurs
Table 1 Prevalence of congenital colour deficiencies
Types of colour visiondeficiency males femalesOverall ~8% ~0.5%Anomalous trichromacy protanomaly 1% 0.01%Deutanomaly 5% 0.4%tritanomaly rare rareDichromacy protanopia 1% 0.01%Deuteranopia 1.5% 0.01%tritanopia* 0.008% 0.008%Monochromacy rod monochromacy rare rarecone monochromacy rare rareatypical monochromacy v. rare v. rare
Modified after Cole (1972), Pease (1998) and estimates from Wright (1952)*
Opponency (Hering)
• Post-images
• Noms des couleurs 4: R V J B
• Pas de teintes RV, JB
• Lumière blanche = R + V = J + B
• Jameson & Hurvich hue cancellation
Hue cancellation (Jameson &
Hurvich)
monochromatique
ajouter V ou Rpour paraître ni V ni R
Codage des couleurs
Sensibilité spectrale des cônes
Figure 1. Spectral sensitivity of the S-cone, M-cone and L-cone. Combined results from various authors using different methods including retinal densitometry from Rushton ( and ), microspectrometry from Brown and Wald ( and “ ) and increment threshold producing artificial monochromasy from Brinley ( and ) and increment threshold measurements from Wald ( ) (From Moses, R. A. and Hart, W. M. (Ed) Adler's Physiology of the Eye, Clinical Application. St. Louis: The C. V. Mosby Company, 1987.(12 K jpeg image)
Décorrelation
Modèle bilinéairede la constancedes couleurs
Maloney &Wandell, 1986
Approximation de 6 réflectivités
3 fonctionsde base
2 fonctionsde base
1 fonctionde base
Fonctions de base de réflectivité
Sommation spatiale et temporelle
THE LAWS OF SPATIAL and TEMPORAL SUMMATION
Spatial Summation: RICCO'S LAW the detectability of a near-threshold flash of light depends only on the product (photons per unit area) X (flash area). Holds only for spots up to 1 degree across at most (in rod vision), and only for very very tiny spots in foveal vision. (NOTE: error in text book) Temporal Summation: BLOCH's LAW the detectability of a near-threshold flash of light depends only on the product (photons/ unit time) X (flash duration). Holds up to 0.2 sec inrod vision, but only up to around 0.05 sec in cone vision.