Chromatic adaptation

The second illuminant L can be considered to be an illuminant to which the eye has adapted itself. Necessary and sufficient conditions for von Kries chromatic adaptation to provide color constancy were derived by West and Brill (1982). 

During the 1960 s, most of the laboratory effort was exploratory in nature. A variety of techniques were employed to differentiate the spectral channels. In animals, electrophysiological techniques were most rewarding. In humans, the techniques were limited to non-invasionary techniques. These were based primarily on differential (chromatic) adaptation and reflection densitometry. The results for humans will be discussed in Section... 

By more completely suppressing the M-channel, the true spectral peak of the L-channel receptors can be determined. The long-dash overlay is for such a condition. The relative amplitudes for this overlay are Figure 5.5.10-10 Wald s figure 2 with overlays. The ksi ik O O 1000 with the same half-amplitudes as upper overlay (dashed line) shows the overall spectral above. Under this more complete adaptation, the peak in sensitivity function of this work. The lower the long wavelength receptor channel is seen to occur at overlay(dashed line) shows the overall spectral sensitivity 625 nm function of this work for a chromatically adapted subject. 

Phycocyanin hexamers (a /3 )(, (A ax 620-635 nm), together with one of the linker polypeptides from the 30 kDa family, form the discs in the PBS rods attached to the APC core in the PBS [124,125], In several cyanobacteria the type of C-PC and the number of C-PC discs in the PBS rods is regulated by light intensity and/or light quality (chromatic adaptation, reviewed in Refs. 126 and 127). C-PC from M. laminosus (Fig. 12) has two PCB chromophores bound to the subunit, the second one being bound to Cys within an insertion of 10 amino acid residues at position 151-160 [113]. The PCB chromophores are singly bound to Cys and Cys - by ring A (Fig. 10). 

Phycoerythrocyanin (PEC, 575 nm) has so far been only in cyanobacteria which do not perform chromatic adaptation [93,111]. It is structurally similar to phycocyanin. The functional difference is caused by the red phycobiliviolin chromophore replacing the blue PCB chromophore bound to Cys in the a --subunit. The /3 -subunit contains two blue PCB chromophores bound to Cys and Cys , homologous to phycocyanin (Table 2, Fig. 12). 

Scheuring S, Sturgis JN. Chromatic adaptation of photosynthetic membranes. Science 2005 309 484-487. 

Tandeau de Marsac, N., Houmard, J (1988). Complementary chromatic adaptation physiological conditions and action spectra. Methods Enzymol. 167, 318-328. 

Wolf, E. and Schiifller, A. (2005) Phycobiliprotein fluorescence of Nostoc punctiforme changes during the life cycle and chromatic adaptation characterization by spectral confocal laser scanning microscopy and spectral unmixing. Plant, Cell Environ., 28, 480-491. 

BARTLESON, c. J. (1979a) Changes in color appearance with variations in chromatic adaptation. Color Research and Application, 4, 119-138. 

BRILL, M. H. and WEST, G. (1986) Chromatic adaptation and colour constancy a possible dichotomy. Color Research and Application, 11, 196-204. 

POINTER, M. R. (1982) Analysis of colour-appearance grids and chromatic-adaptation transforms. Color Research and Application, 1, 113-118. 

WASSEF EGT (1959) Linearity of the relationship between the tristimulus values of corresponding colours seen under different conditions of chromatic adaptation. Optica Acta, 6, 378-393. 

CHROMATIC ADAPTATION IN PORPHYRIDIUM CRUENTUM EXPRESSED IN THE DISTRIBUTION OF EXCITATION ENERGY AND IN THE THYLAKOID HIGH-ENERGY FLUORESCENCE QUENCHING... 

Chromatic Adaptation in Porphyridium cruentum Expressed in the Distribution of Excitation Energy and in the Thylakoid High-Energy Fluorescence Quenching 321... 

An important feature of the color perception is that, besides the raw sensing of tiie color world, the brain processes the information. One of these signal processings deals with the chromatic adaptation to what the brain perceives as the more intense and pleasant white. This is similar to what is known in digital photography as the white balance. This aspect is important as soon as we compare colors together, because a color coordinate is always defined relative to a reference stimulus that is processed as the white color. The reference white depends on the color space that is used to measure the color. 

The xyY color space is the predominant color space for the characterization of luminescent materials because it enables a convenient visualization of the chromaticity of the emitted light that is independent of the visualization condition (no chromatic adaptation). A chromaticity diagram represents all perceivable colors in the xy plane. The border of this diagram is the monochromatic visible spectrum from 380 to 700 nm and what is called the purple axis from red to violet via magenta (Figure 5). 

During M, Schmidt GB and Huber R. Isolation, crystallization, crystal structure analysis and refinement of the constitutive C-phycocyanin from the chromatically adapting cyanobacterium Fremyella dipolysiphon at 1.66A resolution. J Mol Biol. 1991 217 577-592. 

Grossman AR. Chromatic adaptation and the events involved in phycobilisome biosynthesis. Plant Cell Environ. 1990 13 651-666. 

Kehoe DM, Grossman AR. Similarity of a chromatic adaptation sensor to phytochrome and ethylene receptors. Science 1996 273 1409-1412. 

Ohki, K., Watanabe, M., and Fujita, Y, Action of near UV and blue light on the photocontrol of phycobiliprotein formation a complementary chromatic adaptation. Plant Cell Physiol, 23, 651, 1982. 

---