Normalized Color Shifts

Figure 11.10 Computation of color constant descriptors using normalized color shifts. The first layer is the input layer. The second layer computes local space average color. The output is computed in the third layer. The measured red, green, and blue components are stored in cells c, with i e r, g, b. The average of these three components is stored in cell c. Space average color is stored in cells a,, the average of these three components in stored in a. Output cells are denoted by n, (from Ebner 2003c).

Color Shifts and Normalized Color Shifts in Combination with an Increase of Saturation (Nos 4-7)... 

Local space average color, normalized color shifts. 

It has not been determined which hydroxyl group contains the more acidic hydrogen atom corresponding to p Dyes of this type would behave as indicators and exhibit large color shifts with the pH range normally encountered in textile processing. Hence they are always stabUized by coordination with metal ions. 

To better quantify influences of resonant wavelengths on emission characteristics, four parameters are defined the outcoupling efficiency, which is the ratio of the outcoupled emission to internally generated emission the forward enhancement ratio, which is the ratio between the normal-direction luminance of a cavity device to that of an optimized conventional bottom-emitting OLED the color shift, which is defined as [variance of w (0) + variance of w (0)j and measures variation of colors over angles and the Lambertian offset, which is defined as E 1(9)/1(0°) - cos 01 and measures the difference between the emission pattern of a device and the ideal Lambertian distribution (where J(0) is spectrally integrated I(Q,X)). Values of these parameters are obtained using both the simulated data and the measured EL characteristics. 

Calculated values (lines) of (a) color shift, (b) Lambertian offset, (c) forward enhancement ratio, and (d) outcoupling efficiency as a function of the normal-direction resonant wavelength. The calculated results are compared with experimentally obtained values (symbols) of color shift, Lambertian offset, cdA efficiency, and external quantum efficiency in (a)-(d), respectively. The horizontal dashed lines in (a)-(d) represent experimental values of the conventional bottom-emitting device A. (From Lin, C.-L. et al., Appl. Phys. Lett., 90,071111-1, 2007. With permission.)... 

The colors observed by transmission are the principal colors. Slight changes in eolor away from the principal color are observed if the slides are tilted from the normal. This is due to the fact that interference colors shift to lower wavelengths with inereased angle of viewing. 

When fields of different spectral distributions can be adjusted in relative radiance to eliminate all color difference, the result is termed a metameric color match. In a color-matching experiment, a test field is presented next to a comparison field and the observer causes the two fields to match exactly by manipulating the radiances of so-called primaries provided to the comparison field. Such primaries are said to be added this can be accomplished by superposition with a half-silvered mirror, by superimposed images projected onto a screen, by veiy rapid temporal alternation of fields at a rate above the fusion frequency for vision, or by the use of pixels too small and closely packed to be discriminated (as in color television). If the primaries are suitably chosen (no one of them shonldbe matched by ai possible mixture of the other two), a human observer with normal color vision can uniqnely match atty test color by adjusting the radiances of three monochromatic primaries. To accomplish this, it sometimes proves necessary to shift one of the primaries so that it is added to the color being matched it is useful to treat this as a negative radiance of that primary in the test field. The choice of exactly three primaries is by no means arbitrary If only one or two primaries are used, matches are generally impossible, whereas if four or more primaries are allowed, matches are not uniquely determined. 

In contrast to normal spiropyrans, in spironaphthooxazine series, as the polarity of the solvent decreases, a hypsochromic shift of the of the colored form is observed, except for spiropiperidinonaphthooxazine.79 For example, the of 33 shifts to shorter wavelength of ca. 20-60 nm in less polar solvents, such as toluene and cyclohexane, compared to ethanol. This result may suggest that the ground state of the photomerocyanine form in spironaphthooxazine is less polar than the excited state and the neutral quinoid form largely contributes to the photomerocyanine form in the ground state. 

FIGURE 3.12 Normalized PL spectrum of Device 3 (open squares), EL spectrum of Device 1 at 10 V (solid circles), and the EL spectra of Device 2 biased at 8, 10, 12, and 14 V (solid and dashed lines) (left). Color coordinates of the EL vs. applied voltage. The EL of all of the devices blue-shifted with increasing voltage (right). (From Cheon, K.O. and Shinar, J., Appl. Phys., 81, 1738, 2002. With permission.)... 

The experimental value of the constant is 5.67 X 10 8 W-m 2k 4. A few years later, in 1893, Wilhelm Wien examined the shift in color of black-body radiation as the temperature increases and discovered that the wavelength corresponding to the maximum in the intensity, max, is inversely proportional to the temperature, Xmax °c I IT, and therefore that max X T is a constant (Fig. 1.6). This quantitative result is now called Wien s law and is normally written... 

To return to the data from the meditation experiment, it may be that the simpler perceptions of color, light, energy force, and movement represent a shift of the normal perceptual processes to aspects of the stimulus array previously screened out—or it may be that these percepts are registered through the operation of new perceptual processes. In the... 

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