Understanding the nature of color images requires knowledge both of the colorimetric properties of the images themselves and of the media and devices used to create them. In this chapter, the colorimetric characteristics of several important types of electronic devices used for image display will be examined. These devices will be described in terms of their basic technologies, intrinsic grayscale characteristics, and color primaries. We begin with a description of color CRT monitors.
CRT monitors—basic technology
A CRT-based monitor displays colors by producing various intensities of light from its red-, green-, and blue-light-emitting phosphors. RGB light intensities are determined by their respective red, green, and blue control signal voltages. In a typical computer monitor (Figure 4.1), these voltages are generated by digital-to-analog converters (DACs) from digital code values R′G′B′ sent to the DACs. (Note that the prime sign in this code-value designation is used to indicate values nonlinearly related to control signal voltages, as will be discussed in Chapter 5.)
CRT neutral characteristics
For any given set of monitor red, green, and blue phosphors, there is one and only one combination of RGB intensities that will produce a neutral (achromatic) stimulus having a given set of CIE XYZ tristimulus values. For example, Figure 4.2 shows the spectral power distributions for a representative set of CRT phosphor color primaries. Figure 4.3 illustrates ...