The task of the electro-optics design is to deliver the performance indicated in the gamut optimization process. Actually, the electro-optical design is an integral element of the gamut design, since the latter must be based on what is actually achievable, not what is desired. This is particularly challenging in the case of LCD where there are more variables than in projection and fewer degrees of freedom.
In LCD, the color and intensity of the individual primaries is determined mainly by the backlight and color filters spectrum. Presently, different vendors can supply different backlight spectrums. During the optimization process, different phosphors and different ratios of the phosphors are considered for best color gamut, white point and overall brightness.
Regarding color filters, there are two basic requirements:
- For a multiprimary display, new yellow, and cyan filters are required. The yellow should be as saturated as possible, so that the resulting yellow color coordinates will be close to the CIE boundary. The cyan color filter should enable significant deviation from the BG connecting line.
- In order to enlarge the color gamut, one typically wishes to increase the saturation of the RGB colors, and to "fine tune" their color coordinates for optimal gamut coverage. Obviously, the color filters trade off should take into account filter manufacturability and possible influence on display contrast.
Optimization of color filters and backlights, is an essential process in the overall optimization of the color gamut, brightness and white color coordinates of a multiprimary display.
In projection, the lamp is typically a given and the dichroic coatings are not limited in the way that color filters are. As a result, the electro-optical system expert can generally design precisely the system that will deliver the optimal performance specified by the customer. Such performance generally requires tighter tolerances than usual.