Color gamut

In Chapter 2 we have seen that the human eye contains three different types of cones. Color sensations can be produced by varying the amount of light in the sections of the visible spectrum to which the cones respond. Let. S, with i e r, g, bj be the response curves of the red, green, and blue cones. Then the response 2 of each cone i is given by 

---

Practical methods for synthesis and elucidation of the optimum physical forms were developed at Du Pont (13). The violets fill the void in the color gamut when the inorganics are inadequate. The quinacridones may be used in most resins except polymers such as nylon-6,6, polystyrene, and ABS. They are stable up to 275°C and show excellent weatherabiUty. One use is to shade phthalocyanines to match Indanthrone Blue. In carpeting, the quinacridones are recommended for polypropylene, acrylonitrile, polyester, and nylon-6 filaments. Predispersions in plastici2ers ate used in thermoset polyesters, urethanes, and epoxy resins (14). 

Xu, X. and Cortie, M.B. (2006) Shape change and color gamut in gold nanorods, dumbbells and dog-bones. Advanced Functional Materials, 16, 2170-2176. 

Size Format Resolution Contrast ratio Full white brightness Power consumption Color gamut Luminance uniformity Pixel count... 

The performance of AMOLEDs is improved drastically in the past years. In contrast to the data shown in Table 1.2 (which representing development stage in 2002), a set of recent data of a 14.1" WXGA AMLCD made with solution-processed OLED emitters is shown in Table 1.3 [163,175,176], The color gamut is improved to over 60% with respect to NTSC. The luminous and power efficiencies at white point (x 0.28, y 0.31) are >8 cd/A and >5 lm/W. The power efficiency surpasses the performance of AMLCDs, plasma displays, and all other known flat-panel displays in commercial market or under development. A photo of the 14.1" AMOLED display is shown in Figure 1.25b. 

MATERIAL RELATIVE BRIGHTNESS COLOR COORDINATES X Y Y RELATIVE ENERGY EFFICIENCY RELATIVE COLOR GAMUT COMMENT... 

Figure 4.9 Color gamuts of film, a color monitor, and printing inks (Reproduced by permission of Pearson Education from 3D Computer Graphics Third Edition, Alan Watt, Pearson Education Limited, Pearson Education Limited 2000).

Figure 6.14 A scene illuminated with yellow light. The color gamut of this image is highly skewed.

Figure 6.17 A three-dimensional color gamut projected onto the plane b = 1. The resulting two-dimensional gamut is simply the silhouette of the three-dimensional gamut when viewed from the origin.

Figure 11.11 Color gamut for three different values of local space average color. If we assume that the space of possible colors is shifted toward local space average color a, this also implies a smaller color gamut.

Figure 11.12 Shifted color gamut (a). The white point lies at the position a. A color correction can be performed by shifting the colors toward the gray vector (b). Now the color gamut is centered around the gray vector. In order to fully use the available color space, we can increase the color gamut as shown in (c).

Smith AR 1978 Color gamut transform pairs. SIGGRAPH 78 Conference Proceedings, Computer Graphics 12(3), 12-19. 

So is the case in polymers containing additive systems. As will be shown, some additive systems can impart so much light scattering to the base resin that certain colors can no longer be achieved. Or if they can be achieved, other properties may be adversely affected, such as impact strength and cost. In either case, the practical color gamut or palette that is obtainable with this particular resin system is reduced. The discussion below presents the effects that the polymer and its additives can have on colorability. Color data presented in the following tables have been calculated under illuminant D-65,10° observer, specular included, expressed in CIELAB units, unless otherwise noted. 

One can assume that blends of polymers will be more difficult to color than any single component by itself. Diffuse reflection can increase due to internal light reflection or scattering at phase interfaces if the polymers are at least partially immiscible or their refractive indices are significantly different. Blends of translucent polymers are typically more opaque than either resin alone. Furthermore, colorant stability (thermal or chemical) can be adversely affected by the presence of the other polymer(s). As in the case of neat polymers, both circumstances will result in a restricted achievable color gamut for the polymer blend. An example of a prominent polymer blend is GE s Noryl (PS/PPO), which certainly colors much differently than the polystyrene component by itself. 

This class of additives covers a broad range from butadiene to acrylic polymers. Since these additives are polymeric in nature, diffuse reflection will occur at the polymer-modifier interfaces similar to polymer blends. Again, this will result in colors that appear lighter and duller. Table 23.5 contains three examples of impact-modified colors again in polyester compared to the neat resin without modifier. As expected, the impact-modified colors are lighter and have lower chroma. In practice, acrylonitrile butadiene styrene (ABS) or HIPS would have a more restricted color gamut compared to their transparent SAN and polystyrene (PS) base polymers. 

---