S : 0 are the grays. Note that of a color space and range appropriate for the output when S = 0, the value of H is irrelevant. From an artist's device. Thus, the decoding equations are not always the viewpoint, any color with V = 1, S = 1 is a pure pigment exact inverse of the encoding equations. The following (whose color is defined by H). Adding white corresponds equations are suitable for generating RGB values for driving to decreasing S (without changing V); adding black a CRT display, and assume a unity relationship between the corresponds to decreasing V (without changing S). Tones luma in the encoded image and the displayed image. are created by decreasing both S and V. Table 7.2-4 lists R' = 0.981Y + 1.315(C2 - 137) the 75% amplitude, 100% saturated HSV color bars. G' = 0.981Y - 0.311( - 156) - 0.669(C2 - 137) Figure 7.2-13 illustrates the double hexcone HSI color B' = 0.981Y + 1.601(CI - 156) model. The top of the hexcone corresponds to I = 1, or The R'G'B' values should be saturated to a range of white. The point at the base of the hexcone is black and here 0 to 255. The equations above assume the display uses phosphor chromaticities that are the same as the BT.709 GREEN YELLOW reference primaries, and that the video signal luma (V) and the display luminance (L) have the relationship: for V > 0.0812 WHITE L = ((V + 0.099) / 1.099)1/0 for V < 0.0812 L = V / 4.5 MAGENTA HSI, HLS, and HSV Color spaces The HSI (hue, saturation, intensity) and HSV (hue, saturation, value) color spaces were developed to be more "intuitive" in manipulating color and were designed to approximate the way humans perceive and interpret BLACK color. They were developed when colors had to be specified manually, and are rarely used now that users can Figure 7.2-12 Single Hexcone HSV Color Model. CHAPTER 7.2 Colour spaces Table 7.2-4 75% HSV color bars. Nominal range White Yellow Green Magenta Black 0° to 360° 0 to 1 0 to 1 I = 0. Complementary colors are 180° opposite one another were updated in 1960 and 1976; however, the NTSC as me