RGB COLOR MODEL

                                       Based on the tristimulus theory of vision, our eyes perceive color through the stimulation of three visual pigments within the cones of the retina. These visual pigments have a peak sensitivity at wavelengths of about 630 run (red), 530 nm (green), and 450 nm (blue). By comparing intensities in an exceedingly light, we perceive the colour of the sunshine. This theory of vision is that the basis for displaying color output on a video monitor using the three color primaries, red, green, and blue, noted because the RGB color model. we are able to represent this model with the unit cube defined on R, C, and B axes. The origin represents black, and also the vertex with coordinates (1; 1,l) is white.

TABLE FOR RGB (X, Y) CHROMACITY COORDINATES

       

         NTSC Standard             ClE model                      Approx. color 

                                                                                      monitor Values 

R       (0.670.0.330)             (0.735, 0.265)                   (0.628.0.346)

G       (0.210, 0.710)            (0.274, 0.71 7)                  (0.268.0.586)

B       (0.140, 0.080)            (0.167, 0.009)                   (0.1 50, 0.070)

Vertices of the cube on the axes represent the first colors, and also the remaining vertices represent the chromatic colour for every of the first colors. like the XYZ color system, the RGB colour scheme is an additive model. Intensities of the first colors are added to provide other colors. Each color pint within the bounds of the cube is represented because the triple (R, G, B), where values for R, G, and B are assigned within the range from 0 to 1. Thus, a color C, is expressed in RGB components as

                             Cλ = RR + GG + BB

The magenta vertex is obtained by adding red and blue to provide the triple (1, 0, l) and white at (1, l, 1) is that the sum of the red, green, and blue vertices. reminder gray are represented along the most diagonal of the cube from the origin (black) to the white vertex. Each point along this diagonal has an equal contribution from each primary color, in order that a gray shade halfway between black and white is represented as (0.5, 0.5, 0.5). the colour graduations along the front and top planes of the RGB cube. Chromaticity coordinates for an NTSC standard RGB phosphor are listed in Table 15-1. Also listed are the RGB chromaticity coordinates for the CIE RGB color model and also the approximate values used for phosphors in color monitors. the colour gamut for the NTSC standard RGB primaries.