Design of Color Test. Computers these days can display millions of colors so we obviously can't test them all. These are evenly spaced which is convenient for programmers.
Lets whittle it down some more.
So if you look at a vertical line going up through the center of the egg, starting from the bottom and going to the top, you get the colors black, dark grey, grey, light grey, white at the top. Those are the colors that seem to be used on the web, at least nowadays. The colors are shown in table 1 below It has white, grey and black at the center, and the hues circling around them, going from top to bottom of color egg. All combinations of text on background for these colors are shown on Table 2. Given two colors A , B draw horizontal line from A to centerline.