returns the name of a color
RGB integer values of a color.
vector of RGB integer values of a color.
names of the color.
rgb2name returns the color name corresponding to the RGB values
given by its argument. A vector of color names can also be returned if the color has more than 1 name.
b must be integers between 0 and 255
corresponding to colors components red, green and blue. As usual 0 means no intensity and
255 means all the intensity of the color. RGB values can also be given by a vector
If no color is found
 is returned.
The list of all known colors is given by color_list.