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.