Dichromats

Chrom(II)-Ionen lasscn sich leicht aus Chrom(III)-Salzcn dureh Reduktion mit aktiviertem Zink und Salzsaure herstellen. Der Chrom(II)-Salz-Gehalt kann mit Eisen(Ill)-lonen bestimmt werden, indem man die da bei entstehenden Eisen(ll)-Ionen mit Dichromat titriert3. 

The authors believe that a similar mechanism to the above operates for the dichromate-ion dependent path, but that the equilibrium constant K is much smaller. This oxidation presents two novel features, namely the lack of an acidity dependence of the rate and the participation of a term involving dichromatic ion. 

Guth, S. L. et al. (1980). Vector model for normal and dichromatic color vision. Journal of the Optical Society of America 70 197-212. 

Wooten, B. R. and G. Wald (1973). Color-vision mechanisms in the peripheral retinas of normal and dichromatic observers. Journal of General Physiology 61 125-145. 

Badyaev, A. V. and Hill, G. E. 2000. Evolution of sexual dichromatism Contribution of carotenoid- versus melanin-based coloration. Biol. J. Linn. Soc. 69 153-172. 

G. Bortolotti, JJ. Negro, J.L. Telia, T.A. Marchant and D.M. Bird, Sexual dichromatism in birds independent of diet, parasites and androgens. Proc. Real Soc. Lond. B 363 (1996) 1171-1176. 

Fig. 1. Comparisons of the wide-field, flying spot, pinhole detector, and pinhole confocal microscopes. Components include an excitation light source (V), an excitation filter (E), a dichromatic mirror (DM), an emission barrier filter (B), an objective lens (n), a detector (D), and a pinhole (P).

Color Constancy Using a Dichromatic Reflection Model... 

Figure 6.29 The dichromatic reflection model assumes a matte reflection in combination with a specular reflection. Part of the light is reflected at the outer surface. The remainder enters the transparent coating. The second reflection is modeled as being Lambertian. (Reproduced by permission of Pearson Education from 3D Computer Graphics Third Edition, Alan Watt, Pearson Education Limited, Pearson Education Limited 2000.)...

When we now compute chromaticities, the three-dimensional data points are projected onto the plane r + g + b = 1. The linear combination results in a two-dimensional line in chromaticity space. Let Cm be the chromaticity of the matte color and let cs be the chromaticity of the specular color. Then, the dichromatic line on the plane r + g + b = 1... 

Figure 6.31 Two different surfaces have a different diffuse component however, the specular component is the same. The color of the illuminant is located at the intersection of the dichromatic lines.

Figure 6.32 Algorithm of Risson (2003). First, noise is removed by prefiltering the image. Next, the image is segmented. Regions that do not satisfy the assumptions of the dichromatic reflection model are removed. The dichromatic line is computed for the remaining regions. Finally, the most probable point of intersection is computed.

Algorithms based on the dichromatic reflection model are not applicable as the samples are considered to be matte. 

Color constancy using a dichromatic reflection model. 

Risson (2003) The segmentation threshold was set to 0.05. A minimum of five pixels were required for each segmented region. Regions with a saturation less than 0.12 were excluded. The curve of the black-body radiator was not used. The intersections were computed in RGB chromaticity space. All intersections between dichromatic lines were computed and the median, separately for the x-and y-direction, was taken as the position of the illuminant. (threshold=0.05, nLimit=5, minSaturation=0.12)... 

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